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LamproitesandotherPotassium-richigneousrocks:areviewoftheiroccurrence,mineralogyandgeochemistry

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Lamproites and other potassium-rich igneous rocks: a review of their occurrence, mineralogy and geochemistry*

Steven C. Ber gman

S U M M A R Y : In this paper the geological occurrence, geochemistry and mineralogy of ultrapotassic (K,OINa,O>l (molar ratio)) and perpotassic (K20/AI,0,> 1 (molar ratio)) igneous rocks, especially lamproites, are reviewed and discussed in the context oi compositionally-similar man~le-derived melts

L.amproites are K. and Mgrich igneous rocks (typically K , 0 > 5 wt X , MgO>S wt X )

tectonic enviromnents; they range in age from the eariy Proterozoic dykes at Holsteinsborg, W Greenland, and Cheiima India, and Precambrian pipe at Argyle, W Australia, to the Middle Pleislocene flows and the Recent volcanics of the Leucite Hills, Wyoming, and Gaussberg, Antarctica, respectively Intrusive and extrusive forms oi lamproites include flows, a variety of pyroclastics (welded tuffs, piperno, air-fall tuffs, volcanic breccias etc ), cinder cones, dykes, sills and diatremes. Whereas kimberlite diatremes tend to be carrot shaped, the shape of olivine lamproite diatremes approximates a sherbet..glass The recent discovery of diamondiferous Iamproites of large volumetric proportion in the E and W Kimberleys, NW Australia, and the reclassification of the diamondiferous micaceous peridotite at Prairie Creek, Arkansas, as a lamproite substantiate their economic importance The 21 lamproite suites considered here tend to be localized marginal to continental craton cores in areas that overlie fossil Beniofl zones, in contrast with the general occurrence of kimberlites more interior tocontinental cratons

The petrographic diversity of lamproites has historically hindered the development of a concise and, universal classification and nomenclature Lamproites aie distinguished from kimberlites and alkali basalts (and lamprophyres)in terms of mineralogy, mineralchemistry, geochemistry and volcanic extrusive character Relative to kimberlites, lamproites are enriched in K, Si, Ti, Al Rb, Sr, Zr and Ba and depleted in CO,, Ca, Mg, Fe, Ni, Co and CI Iamproites are characterized by the general presence of phlogopite, diopside, leucite and K-richterite, occasional glass, olivine, sanidine, priderite, peravskite, wadeite, apatite and chrome spinel, and very rare ilmenite L.amproite &nphibolis, diopsidesand phlogopites are distinctlv de~le ted in AI,O, relative to those of nearly all other ieneous rocks Lamnroite , . . " - magmas are produced by the partial melting of old refractory mantle peridotite (approaching aduniteor harzburgite inmineralogy)thatwasenrichedinK-bearing andotherincompatible- element-enriched phases, such as phlogopite and apatite, most probabir as a result of some metasomatic event which occurred prior to melting In contrast with alkali basalt and kimberlite melts which are apparently produced from the partial melting of a C02-enriched mantle peridotite (i e a source with a relatively high CO,/H,O ratio), water is the key volatile species involved with Iamproite petrogenesis (source with a low CO,/H,O ratio)

Introduction

'Lamproite' designates a K.rich mafic to ultra- mafic alkaline igneous rock as originally defined by Paul Niggli and P J Beger i n 1923 in the context of Niggli's detailed chemical system of igneous rock classification Relative t o nearly all other igneous rock types, they possess high K/Na a n d K/Al ratios I n addition, lamproite mineral- ogy a n d geochemistry are unparalleled Niggli a n d Beger recognized two subtypes of the lamproite clan, based o n the distinctive compo-

*This paper is dedicated to the memory of the late I h G Sahama who contributed much to the infant stages of the lamproite revolution

sitions of rocks from the Leucite Hills, Wyoming, a n d SE Spain, a n d included fortunite, verite, orendite, prowersite, wyomingite and jumillite in the c lan 'Troger (1915) redefined the term 'lamproite' as the extrusive equivalent of lampro- phyres tha t a l e rich i n K a n d M g I n the ensuing five decades, over 150papershave been published on the subject of lamproites a n d an exceedingly complex terminology has been generated Whereas the earliest studies emphasized the two classic localities in Spain and Wyoming, it is the purpose of this paper t o summarize, compare and contrast the geological, geochemical and miner- alogical characteristics of ? I lampcoite occus- rences o n six continents a n d place these lamproite features i n the context of compositionally allied

From FITION, I G & LIPION, B G J (eds), 1987, Alkalrne Igneous Rocks Geological Society Spec~al Publication No ?0, pp 103-190

104 S C ' B

alkaline igneous rocks, including other ultrapo- tassic rocks, kimberlites, lamprophyresandalkali basalts While not all K-.rich rocks will be reviewed, several of the more important suites, geographically significant localities (because of close proximity to lamproites) or localities which have been previously described as Iamproites but are not considered so in the present discussion will be included in this discussion This paper is not meant to be an exhaustive review of K-rich rocks, but rathera springboard to theK..richrock liter ature

Prior to the late 1970s Iamproites were thought torepresent petrologicalodditiesof limited extent and importance with extreme and exotic mineral assemblages and chemical compositions (e g Turner & Ver hougen 1960) However, the discov- ery of diamond-.bearing lamproites at Ellendale and Argyle, on the SW and E margins of the Kimberley craton in NW Australia (Atkinson et a1 1984a, b ; laques et a1 1984), and the reclassification of the diamond-bearing mica- ceous peridotite at Prairie Creek, Murfieesboro, Arkansas, from a kimberlite (albeit anomalous) (Miser & Ross 1923; Bolivar 1977; Lewis 1977; Meyer et a1 1977) to a lamproite (Bolivar 1984; Scott-Smith & Skinner 1984a, b) have placed the lamproite clan in an important position in terms of both petrogenesis and economics Not only must diamond-exploration models be revised to include lamproites but, in addition to kimberlites, certain members of a second group of igneous rocks must originate from within the diamond stability field in the Earth's upper mantle (depths of greater than 150 km) and be explosively transported to the surface in order to preserve diamonds that are unstable i11 these oxidized magmas The diamondiferous sandy tuff l a m proite at Argyle, W Australia, is among the largest (125 acres and more than 100 million tons) and is the highest grade (about 600 ct per 100 ton) igneous diamond deposit thus far discovered, dwarfing many of the S African kimberlite pipes (typically 20-80 ct per 100 tons in grade and 20- 60 acres in area) in the quantity of diamonds contained

This paper is olganized as follows After a brief' consideration of the igneous geochemistiy of K, Naand Al, previous reviewsand benchmark papers on lamproites and other ultrapotassic igneous rocks will be briefly summarized The nomenclature and classificationof lamproites will then be discussed, followed by a review of the geological occurrenceof lamproite and significant compositionally related suites The major-, trace.. element and isotope geochemistry of' lamproites and their mineral chemistry will then be summa- rizedandcompared with those of conipositionally

'ergmnn

related rock types. Finally, after a review of expe~imental data involving lamproites, current theories on the petrogenesis of lamproites will be presented It should be noted that, while the literature is presented in an objective forum, many of the author's opinions, which are not necessarily shared by all workers in this con- stantly debated arena of alkaline rocks, have infiltrated the review, especially in the discussion section

K, Na and A1 in igneous systems

Important rock-forming minerals containing sub-, stantial proportions of both K and A1 include i

sanidine, biotite, leucite and rare kalsilite; the molar ratio KIA1 is nearly always less than unity for these minerals Relative to both A1 and Na, K displays a remarkable regularity in its general distribution and abundance in igneousrocks(Fig 1) In a bulk-.rock sense, K is more incompatible than A1 and N a in basaltic and more differen- tiated igneous systems subjected to processes involving either partial melting or fractional crystallization For example, both KIA1 and K/ Na increase in progressing from the 'bulk Earth' (carbonaceous cbondrites) or the 'primitive upper mantle' to basalts (either alkaline or tholeiitic) as the result of partial melting, possibly combined with a small amount of' fractionation (Fig I). These ratios both increase in the generalized sequence basalt, andesite, dacite, each progres- sively increasing in the degree of fractional crystallization that the given magma has experi- enced (Fig I )

For the vast majority of igneous rocks, K,O/ Na,O molar ratios are less than 1 0 As has been suggested by Johannsen (1931,1937,1935,1939), those rocks with K 2 0 / N a ? 0 (molar) ratios of 1- 3 are best termed 'potassic' Relatively common rockswithK,O/Na,O ratiosof about 1-3 include some granites, rhyolites, syenites, trachytes, la- tites, leucite tephrites, leucite basanites and minettes Rarer rock types with a 'potassic' character include shonkinites and absarokites Those rocks with K20/Na ,0 ratios in excess of 3 should be termed 'ultrapotassic'and include some minettes, leucite phonolites, rare alkaline rocks (e g juvites), kimberlites and lamproites

To describe the relative amounts of'the alkalis and Al, Shand (1927) used the term 'peralkaline' for those rocks with the sum of molecular K 2 0 and N a 2 0 in excess of molecular A12C), The numericalvalueof theratio(K,O + Na20)/Al2O, has been named the azpaitic index or coefficient by Ussing (1912) and has been discussed by Polanski (1949) and Ssrensen (1960) Peralkaline

Lamproztes and K-rrch zgneozls rocks 105

.. - . CRUST "AILOR d MCCLENNAN > % ? I

SilMATEI OF CONTINENTAL CRUST

O iEP SE* CARBONilE SEDIMENTS

0 0'5 1 0 ( a ) K 2 0 1 Na20 (WT BASIS)

. NSW E KIMBERLITL A SAYOSlOltES

A SHALES . AYERACE ROCK *PES + uupaotrr s u ~ i s AvEamEs . OTIIFR POTASSIC IULiRAPOIASSIC ROCK EUliEJ

0 5 10 ( b ) K20 1 Na20 (WT RATIO)

FIG 1 (a) Plot of the covariation of K,0/A120, and K20 /Na20 for average igneous rocks and carbonaceous chondrites (Nockolds 1954; Goles 1967; Mason 1967, 1979; LeMaitre 1976) and a few sediments (Turekian & Wedepohl 1961) compared with the estimated compositions of various portions of the Earth (continental crust (Clark & Washington 1924; Goldschmidt 193 3 ; Poldervaast 1955; Ronov & Yaroshevsky 1969), primitive mantle (Taylor 1979), and lower, upper and Archaean crust (Taylor & McLennan 1981)) Note that Earth mate~ials show a regular and positive correlation between the degree of'perpotassic' and 'ultiapotassic' char acter

(b) Same plot as (a) except that the scale is reduced to include the average compositions of lamproites and related rocks (see text); the shaded region corresponds to the field of Earth materials in (a) Three sedimentary rock compositions are also shown Lamproites are unparalleled in their degree of K enrichment relative to Al and Na See Appendix 3 for rock suite abbreviations

rock types include some rhyolites, trachytes, syenites, granites, minettes, lamproites and kim- berlites Most lamproites and some kimberlites (e g the Group I1 kimberlites of S Africa (Smith 1983a, b) and other micaceous kimberlites) are among the only rock types that are so enriched in K ,O that it is present in excess of A l20 , (atomic basis) Johannsen (1931, 1913, 19 35, 1939) sug-

gested that the term 'pe~potassic ' be used to describe these exotic rocks Therefore most lamproites atid some micas ich kimberlites and minettes share the unique quality of being among the only rock types that are both ultrapotassic and perpotassic 'Those rocks whose elevated K contents are due to near-surface or late-stage magmatic alteration (such as the potassic altera-

tion zones in some fenites and porphyry systems) are excluded from the present discussion

P~evious reviews

Lamproites and other K-rich alkaline rocks have been the subject of many important reviews and contributions, although no-one has attempted a comprehensi\e integrated synthesis of lam- proites Various aspects of selected potassic and ultrapotassic rock suites have been discussed in many benchmark papers and books on alkaline and other igneousrocks (Jensen 1908; Daly 1910, 1914, 1933; Niggli 1923; Shand 1927; Smyth 1927; Terzaghi 1935; Saether 1950; Turner & Verhoogen 1960; Sobolev 1970; Bardet 1973, 1974,1977; Carmichaeletal 1974; Stewart 1979; Smith 1984b; Venturelli et a1 1985; Foley et a l , in review) Niggli (1923, pp 182-5) and Beger (1921, pp 448-51) were the first to synthesize the early 19?0s understanding of ultrapotassic rocks Their two subtypes of lamproites were character- ized by the following Niggli values (Niggli values are the ratio of the weight per cent oxide to the gram molecular weight, normalized to one cation x 1000; k= kj(na + k), mg=mgj(mg+fe))

Subiype 5 1 a1 fm L uik k mg ~//m Murcla 140 16 55 13 16 0 80 0 8 0 0 2 3 Wyoming 165 18 41 14 27 0 85 0 75 0 15

Lacroix (1926) summarized the systematics of syenitic leucite-bearing rocks including those of the Leucite Hills and Gaussberg On the basis of petrography and geochemistry, Sahama (1974) differentiated orenditic from kamafugitic rocks in a review of K-rich igneous rocks; the former group corresponds to the lamproites discussed here A recent book reviewing mineralogical, petrological, geochemical and experimental as., pects of rocks that contain modal leucite (Gupta & Yagi 1980) includes a discussion of many of the lamproite suites synthesized and updated in the present work Wendlandt & Eggler (1980a) performed a statistical study of 835 leucite- normative Cenozoic volcanic rocks and recog- nized two compositionally-distinct sub-groups, one enriched in K,O and AI,O, but depleted in MgO and another enriched in MgO but depleted in K,O and AI,O, Interestingly, lamproites apparently did not fill in either group and were evidently not included in the original data set (RKNFSYS; Chayes 1976) Mitchell (1985) contributed a comprehensive review of the mineralogy and mineral chemistry of lamproites and Wagner & Velde (1986a) discussed the mineral chemistry of' 10 K-richterite-bearing lamproites fromsix suites Rock (1987) compares

and contrasts lamproites with lamprophyres and Dawson (198'7) compares olivine-rich lamproites with micaceous kimberlites Foley (1985) consid- ers the oxidation state of lamproite magmas

'Shoshonites' (i e those andesitic intrusive and extrusive rocks with K,O/Na,O near or greater than 1 0, with slight enrichments in CaO and MgO and depletions in FeO and TiO, ielative to Na,O-rich alkali basaltic rocks) and related potassic rocks, which are minor but ubiquitous components of many island arcs and continental margins, are much more aluminous than lam. proites and have received attention in review papers by Joplin (1965, 1965) and Morrison (1980) Recent contributions to the petrogenesis of shoshonite magmas include Gest & McBirney (1977), Boccaletti eta1 (1978), Pagel & L,eterries (1980), Ewart (1982), Keller (1981) and Friend & Janardhan (1984), and references cited therein

K-rich rocks occur as local variations within various portions of alkaline pyroxenite-bearing ultramafic plutons and gneiss complexes in the Oman Mountains, Arabia (Searle 1984), at Ampipal in the central Nepal Himalayas (Lap serre 1976), at Shaki and Okeho in the basement complex of W Nigeria (Oyawoye 1976), in the Batbjerg complex in E Greenland (Gittins et a1 1980; Brooks et a1 1981), in the Blue Mountain complex, New Zealand (Grapes 1975), in S Greenland (Upton & Thomas 1973) and in the Mordor complex in central Australia (Langwor- thy &Black 1978) among others Thepetrogenetic relationship between these rocks and lamproites must await more detailed study

Many alkalic-carbonatitic complexes possess fenitized zones which are characterized by rocks composed almost entirely of' potassium feldspar (Heinrich 1966; McKie 1966; Verwoerd 1966; Heinrich & Moore 1970) Whereas these rocks possess some geochemical and mineralogical features common to lamproites, they tend to be extremely depleted in MgO and it is clear that their petrogenesis and paragenesis are distinct from those of lamproites

1,amproite nomenclature and classification

Lamproite terminology has historically been one of the most complex and disjointed of that for any group of igneous rocks (Table 1) In the f i~st half of this century, a nomenclature was devei- oped that centred around the minexalogy of individual iampsoite suites with little regard to lamproite suites elsewhere in the world Table 1 summarizes the sometimes redundant terms that

Lamprortes and K-rzch zgneozls rocks

T A B L E 1 Hr~toric Iummary ojlamprorte term~nology

Rock term Principal mineral and/or phenocryst GGM Rock suite Original reference assemblage --- --

opx 01 amph cpx phl leuc san - - Wyomingite x x Orendite x C ) Leucite Hills. U S A Cross 1897 Madupite x x x Cedricite Y x x 'l Mamrlite x x Wolgid~te x x x x } Frtzroy Basin, W Australm Waded Prdn I940

Fitzrovite : x x x ) ~eri te ' x x x Jumillite x } Muscia-Almeria, S I Spain Osann 1899

: X X X X ,

Cancarixite : x x x Murcia--Almeria, SE Spain Parga-Pondal 1935 Fortunite x x x Murcia-Almeria, SE Spain De Yarza 1893 Cocite x x x x x x Coc-Pia, N Vietnam Lacroix 1933b Kajanite x x x Oeie Kajan, Borneo Brouwer 1909;

Lacxoix 1926 Gaussbesgite x x x (;aussberg, Antarctica Lacroix 1926 -- opx, orthopyroxene; 01, olivine; amph, amphibole; cpx, clinopyroxene; phl, phlogopite; leuc, leucite; san, sanidine; GGM, glassy groundmass

have been introduced fbr mineral assemblages characteristic of individual or several lamproite suites Note, for example, that fitzroyite and wyomingite are equivalent, and cocite and jumi- lite are mineralogically identical Unfortunately, the most ~ecen t I.eport of the IUGS Subcommis- sion on the Systematics of Igneous Rocks, which specifically emphasized the classification and nomenclature of lamprophyres, carbonatites and other alkaline rocks (Streckeisen 1980), neglected to include lamproites in its discussion Under the earlier IUGS scheme (Streckeisen 1967), lam- proites would fall in the compositional fields of alkali trachyte, phonolite, phonolite foidite or leucitite Troger (1935) and Johannsen (1931, 1933, 1935, 1919) describe selagites from Italy which some workers (D Velde, personal com- munication, 1985) place in the lamproite clan However, selagites contain about 10% plagioclase (oligoclase) and therefore do not meet the mineralogical criteria for lamproites discussed in more detail below

Although Middlemost (19'75) included lam- proites in the basalt clan, lamproites should not be considered as basalts (despite the appearance of basaltic cinder cones and lava flows in many lamproite occurrences such as the L.eucite Hills) L.amproites do not contain plagioclase, a phase which is generally regarded as an essential component of basalts Note, however, that Zirkel (1570) and Rosenbusch (1877) used the term 'leucite basalt' for rocks composed of leucite, augite and olivine which were devoid of plagio-

clase If olivine lamproites are to be regarded as basalts, kimberlites must also be included in the basalt clan

Lamproites have historically been split up and placed in a variety of sometimes distinct rock groups; these classifications, furthermore, have hindered the development of a clear understand- ing of the lamproite clan and its petrogenesis Rosenbusch (1887) classed the Praixie Creek, Arkansas, lamproite with biotite-peridotites but the L.eucite Hills rocks withleucite basalts Niggli (1923) introduced the term 'Mediterranean prov- ince type' for potassic alkaline rocks of syenitic to shonkinitic composition; the type locality was the Roman co-magmatic province whose rocks are not lamproites because oftheir metaluminous to peraluminous character Nevertheless, some lamproite suites have been included in the Mediterranean magma type (e g Turner & Verhoogen 1960) Lacroix (193 3) put lamproites in his Division 11, Family A : missourites, leucitites and albanites ?'roger (1935) placed the Prairie Creek, Arkansas, lamproite in his glim- merite Family (no '721, olivine-glimmerite) Other Iamproites fall into Troger's nepheline syenite (orendite) and shonkinite (cocite, wyom ingite, gaussbergite, jumillite) families. Johan nsen (1931, 1913, 1915, 19.39) detailed the mineialogy and texture of many of'the lamproites and ultrapotassic rocks known at that time and placed lamproites andother ultrapotassic rocks in six different families within three classes of his rock-classification scheme These families

spanned a wide range of compositions, including feldspathoidal rocks, peridotites, trachytes, per., knites and alkali syenites Williams et a1 (1954) included Leucite Hills lamproites in the leucite phonolite petrographic group Rittmann (l951), who considered both mineralogy and geochem- istry in devising his nomenclature for volcanic rocks, placed lamproites in the 'lamproitic phon- olite', 'lamproitic leucitite'or 'lamproite trachyte' groups He additionally suggested different terms for established lamproite rock names, i e madu- piterpheno-phlogopite-mafitite~~amproite leu- citite,veriterpheno-mafitite(ph1ogopite)~lamp- roitic trachyte, and wyomingite~pheno-leucite- mafititeGlamproiti phonolite Sahama (1974) classified K-rich alkaline rocks into two groups, lamproitic (or orentlitic) and kamafugitic, on the basisof chemistry and petrography Barton(1979) recognized three sub-.groups of K-rich alkaline rocks on the basis of bulk rock and mineral chemistry and petrography: the Leucite Hills type, the roro-Ankole type and the Roman province type. The 21 lamproite suites considered below fall in both the Leucite Hills and Roman province fields in Barton's scheme; none, how., ever, overlaps the Toro-Ankole field On the basis of petrographic modal and texlural variability, Mitchell (1985) suggested that two broad sub- divisions of lamproites be made: phlogopite- sanidine--leucite-diopside-lamproites and mad- upitic lamproites The former group possesses resorbed phenocrystal phlogopite and includes wyomingites, orendites, fitzroyites, cedricites, verites etc The latter group is characterized by poikilitic groundmass phlogopite and includes madupites, wolgidites and jumillites

As many lamproites possess an extremely fine- grained or glassy gioundmass, classification based on mineral abundances alone is doomed to failure because of the uncertainty in the mineral equivalent of the groundmass Since bulk-rock compositionreflectsmineral chemistry and abun- dance of component phases (and vice versa), whole-rock geochemistry can also be used in establishing a classification system for lam- proites This is extremely useful for fine-grained rocks and is essential for glass-rich rocks None- the-less, it is often difficult to pigeon-hole rocks solely on the basis of' their geochemistry Scott- Smith & Skinner (1984b) suggested classifying lamproites on the basis of the modal abundance of principal primary minerals, following an analogous scheme proposed by Skinner & Clem- ent (1979) and Clement et a1 (1977) for kimber. lites Their six major divisions were phlogopite, K..richterite, olivine, diopside, sanidine and glassy lamproites Mitchell (1985) has followed their suggestion but has criticized the elimination

of leucite from the list of major phases and the inclusion of glass in a mineralogical classification, two criticisms that are taken ~ n t o consideration below 'Therefore leucite is substituted for glass in the six major sub-divisions proposed by Scott.. Smith & Skinner (1984b) Minerals of secondary importance can be used as modifiers to the most abundant phases and permit further sub-divisions to these six major classes Mitchell (1985) also recommended recognizing the texture of phlogo- pite in the classification, and suggested the following sub-divisions: phlogopite lamproites (in which phlogopite occurs as phenocrysts) and madupitic lamproites (in which phlogopite is poikilitic in the groundmass) Mitchell's miner- alogical classification removes many of the redundancies 01' the classical terminology, and tends to over-simplify the mineralogy of a given rock Nevertheless, until more is known about the genetic controls on the petrography of lamproites, this classfication scheme is the best alternative

Lamproite defined

The definition of lampioite proposed and used here is based on those of Scott-Smith & Skinner (1984b) and Mitchell (1985) but includes several other parameters It is suggested that the term 'lamproite' be applied to those intrusive and/or (more commonly) extrusive rocks that fulfil the following mineralogical and/or geochemical con-. straints

1 Dominant (more than 5%--30%), althoughnot essential, primary phases (groundmass or pheno- cryst) include titanian phlogopite (Al-poor), cli- nopyroxene (Al..poo~ diopside, more rarely diopsidic augite), Al-poor alkali amphibole (com- monly K-Ti-richterite, more rarely K-riebeckite, K-arfvedsonite or other alkali amphiboles), oli- vine (often in aggregated grains but also euhed- ral), leucite (Na-poor, commonly Fe-rich) and sanidine (commonly Fe-rich) 2 Accessory (less than 5%-10%) but often characteristic primary phases include spinel (intermediate Cr-Mg-Fe-Al-Ti compositions), priderite ((K,Ba)(Ti,Fe'i)8016), wadeite (K,Zr,Si,0,8), shcherbakovite ((Na,K) (Ba,K) Ti2Si,0,,), jeppeite ((K,Ba),(Ti,Fe),O, ,), apa- tite, perovskite, sphene, armalcolite ((Mg,Fe)T i,O,,), enstatite (rare) and ilmenite (very rare) 3 Alteration or secondary phases comprise analcime, chlorite, quartz, T O polymorphs,

Lnmproztes and K-rzh zgneozls rocks 109

carbonate minerals, nontronite (and other zeo- lites), chlorite, serpentine, barite (Sr-rich), albite and a variety of clay minerals 4 If a rock carries any of the following, it talk outside the lamproite renru rtricto group: (a) primary plagioclase (late- to post-magmatic sec- ondary albite can occur); (b) melilite or monticel- lite (places a rock in the more calcic kamafugitic, ultramafic, lamprophyre, kimberlite or basalt clans); (c) kalsilite (requires aSiOz activity much lower than that observed in lamproites); (d) nepheline, sodalite, nosean and haliyne (these sodic phases are not compatible with an ultrapo- tassic assemblage); (e) melanite (despite the TiO,-richand Al-poor compositionof lamproites, melanite contains too much Fe to be stable) 5 Xenoliths and xenocrysts are neither neces- sary nor sufficient to the definition of lamproites but are mentioned to pe;mit further distinction of lamproites fIom kimberlites and ultramafic to mafic lamprophyres Cr-rich pyrope xenocrysts, which are ubiquitous components of kimberlites, are rare components of olivine iamproites (e g Ellendale, Argyle, Prairie Creek) 'Dogtooth olivine' aggreoated monomineralic xenoliths are 4 a characteristic feature of' many olivine lam- proitesie . Ellendale. Prairie Creek (Scott-Smith and ~ k i n ~ e r 1984a, b)) and are distinct from the ubiquitous rounded olivine niacrocysts of k i m berlites Spinel and garnet lherzolite xenoliths are extremely rare in lamproites but common in kimberlites The most common xenoliths found in lamproites (apart from ubiquitous shallow- crustal country-rock fragments) are biotitite, biotite-clinopyroxenite and pyroxenite xenoliths that are most probably cognate 6 Mineral chemistry (see below) can also be used to distinguish between lamproites and other rocks

Occurrences of'lamproites and other potassic to ultrapotassic rocks

This section summarizes geological and petro- logical data and literature pertinent to those localities which contain rocks that conform to the constraints discussed above and hence can be called lamproite rensu rtricto Localities contain- ing potassic-ultrapotassic rocks which do not meet the requirements for classification as lam., proites will also be considered, and the rationale fbr not including them in the lamproite group will be given Tables 2 and 3 abstract the geological parameters of each locality and most of these are plotted in Fig 2 Note that the abbreviations used to reference each locality will be used throughout this paper and, in particular, that those localities not recognized as containing lamproites renru rtricto are set in square brackets An alphabetical listing of' the abbreviations is given in Appendix 1 Figure 3 illustrates the variety of rock textures observed in the suites from Australia and N America, and Fig 4 shows representative thin-.section photomicrographs from 11 lamp~oite localities

N America and Greenland

Kimberlites, lamproites, carbonatites and allied rocks are widespread in N America (Fig 5); however, incontrastwith kimberlites andcarbon. atites, lamproites do not occur in the interior of the craton but are generally located near its margin (Meyer 1976; Tuttle & Gittins 1966) The estimated age of the crustal basement to these lamproite localities vaiies from 1 5 x lo3 to 2 5 x 103 Ma

Enolee Vermiculite dirtlict S Caloiina ( E VD) (34' 30' N 82' W)

Late Proterozoic to Early Palaeozoic vermiculite bodies occu~ throughout the Appalachians and

When a rock possesses the following general Piedmont and are best exposed and studied near compositional features, it is suggested that it be Enoree, SC, just W of the Kings Mountain Belt included in the lamproite clan: KIO/A1,O,:.O 8 (Stewart 1949; McClure 1963; L.ibby 1975). (molar), K20/Na,0:.4 (mola~), Mg number :. Palaeozoic metamoruhism ~roduced a mineral 70, with general compositional ranges of 45-55 wt % SiO?. 4-10 wt % A120,, 1-5 wt % TiO,, 2- 10 wt % CaO, 5-10 wt % K,O, 0 2-1 5 wt % Na,O, 0 5-2 0 wt % P 2 0 , and 1 0-3 0 wt %BaO. It is recommended that both mineralogy and geochemistry be used to distinguish lamproites from other rocks However, where mineral data are lacking or impossible to acquire (glassy rocks), these compositions can be used with caution

assemblage of'phlogopite, diopside, tremolite (or talc), K-feldspar, apatite, sphene, monazite and zircon Metamorphism has clearly modified the primary mineralogy and only a few of the major lamproite phases are present The geochemical character of the EVD rocks, provided that it has not been modified by the metamorphism, is diagnostically lamproitic and nearly identical with the geochemistry of the average lamproite (Tables 4 and 5)

TABLE 2. Ln~nprofre iocalitfes a n d p r o v r n c e s ,.. ,-. - " Locdllly Age (Ma) Counrrv Rocks Tecton~csett~ng I~~~rus~ve lEx t rus~ve Textural types Petrographic cypes Importanr mmerals

forms

Hills Pond. KS (HPj

Karnas & Moon Can- yon. U T (KAM)

Leuace Hills. WY ILHi

Pralrle CrceK. Crater of Diamonds Park. Murireesboro. AR (PRA)

Smotv Butte. MT(SUj

Holste~nsborg, W Greenland (HOL)

500-700 Peiit~c schisrs, granirlc gnelsses. merasedi- mentary and rneta- volcanic rocks

90 Mesozo8c shales, lime- stones

1 3 4 0 Proterozoic. Palaeozotc and Mesozotc shales, sandstones

1.1-1 2 5 Cretaceous carbonates, Terrlarv ciasric sedi- mentary rocks

106 Carboniferous and Cre- taceous clastic sedi-

Inner Pledmont of the Small plutons Appaldchlan orogen

Palaeozolc platform on Small piurons, sills. Archaean craton dykes

W margln, Colorado Small olugs, dvKes, Platenu flows

Green River Basm plat- Cinder cones. flows. iorm seiis on margln necks, dykes. Inrro- of Archaean craton s,ve sheets, pyroclas- bsoemenr ucs. bedded tuffs

SE margin of Ouacilira Diatremes. dykes, pyro- orogen clasrtcs. bedded ruffs

27 Palaeacene sedimentary Platform sedlmenrs Ar- D y ~ e s sinall plugs, pyr- rocks chaeancraron base- oclastics, bedded

men^ ruffs 1200 M~ddle Protcroro~c Stable Precambrnn Dykes

meraln0Tl)hlCE craton

Massrvc hypabyssal. lncrurlve brecctas

Massive hypabyssdl vesrcular lavas

Masswe. hypabyssal. vesicular lavas; scorta. >ntrcstve brec- ems. lapilli, rofilag- glomerate, magmatrc

Massxve, hypabyssai. tnrruswe breccjas, rufflagglomerate. magmatic, aurolithic breccla

Masstve hypabyssal in- truslve brecctas. r u m agglomerate

Masssve, hvbabyssal, vesicular brecc~ss

Olivine lamprolie, phlogo- plre Iamprolte

(Tracbvres. meiteigtresi Wyommglres. mtca per,- dotxter, biot~te olivlnlrz

Wyom~ngtte. orendite, msduplre, phlogoirtre lamirrolte

Olivine lamprorre, phlogo- plre inmprolre

Olwzne Idrnprotte, phlogo- plre larn~rolre leuclte lamvrolte

Phlogoptce-leuclre-rlchter- 11e iamnrolre

Europe Murcla & Aimern 8.6-7.2 MesozolcITertlary sedi- Hercynlan orogen- Plugs: small olutans Massive. scona. inrru- Phiogo~~rc-leuc>re-diov

Province. Spaln mentarv rocks Benc cordillera sub- swe brecclas side-sanidine lamvrolres (MAP) doctlon relared (cancar$xlte. vente,lom-

illite, forruntre) NW Iralv (NWI) 29-33 Eclogic,cm~caschisrs. Alo~neorogen Dykes an0 rare flows Massrve porphyriric Phlogoptre-diopside-sanl-

caicschisrs, gnelsses dinelamoro~te Cornwall, U K

Pende~>nls(PEN) Permo-Car- Devonlanslares Hercyntan orogen Dykes and stlls Hypabyssal masswe Sanldrne lamprolre bonlierous

Eiolmead Farm 281 Perm,an red beds Hercynlan orogen Flows dyKes Massive Olivine-phlogopxte lam- (IILMj prom

Sisco; Corsfca, France 14 Mesozoic schists Marg!n/Al~iae orogen Thin stlls (1.5-4 mj Massive porphvr!ric Phlogoolre-rlchterlte lam- (CORi vrot~e

PH. OL. CP, AA. PV. BA, SP, SN

PH, CP, OL, SN MT AA AP AN

PET. CP. SN. LU. AN, OL, SP, UA, AP, PV. MT, SP

OL; PH, CP. AA. t) SN; SP, WD. PR: PV. SE, BA. 0 AP b

2 PH. CP. OL. LU. Og

AN. SP. AA. MT 3

PH. OL CP AA LC SN OP SP AP, AN C C

PH, CP, SN AA OL, MT. AP. SE

SN. PH. Q, CC. AA. CP. AP. RT. BA. SP HM. 11.. ZR. SU

OL, PH, SN. CP. AN, MT. AP. PV

PH. AA, SN. OL. CP. AP, SE

Afircn Bob1 &Seguela, Ivory 1150-14301

Coast (BOB) . . Luangwa Graben, <250

Zambta (LUA)

Southern Afrlca (Pne~l, Mesozoic Swarcruggens, Post- masburg etc) (PPS)

n rrsrrolm Argyle. \V A (ARG'I Precamhrlan

(600-9007)

Mount Bavllss (MBAY) 413-430

Priestlev Peak (PP) Palaeozo~c

Precamhrlancrvsralllne Stablecralon Sheared aykes rocks

Karoo sedtmenrary Extensxon of W margm Dykes, pipes, craters rocks Precambrlan of E Afrlcnn rxft crystalilne rocks

Precambrlan crysralllne Interlor ano margmal to Dykes dlatremes rocks srable craton

Prorerozo!~ sed~men- Halls Creek Prorerozo~c D~atreme, dvKes ~ a r y rocks mobile belt

Palaeozolc sltales. iime- Terr~ary baoln in a cra- Necks, flows. avkes, stones. sandstones. ronlzed Proterozoic plugs, diatremes, pyr- Pliocene snales mobile belt oclastics. agglomer-

ales

Precamhrlan Arcliaean craton mar- Lavas, c~nderconea gin palagonlre tuffs, ag-

glomerares Precambrian Arcnaeancraton mar- Dykes

gin Precambr!an nigh- Archaean srable cracon Dvkes

grademetamorph~c margtn rocks

Metamorphoses, schrs- Le~rcxre tarnvrotre. fitzrov- tose imasslve) lte, wvomlnglte

E~lciastrc ( 7 ) and Pvro- ollvlne roolwlne-leuclre clastlc lap!lll ruffs iam~roites massrve, hvpabvssal . .

Masstve. hypabyssal, Ollvlne-phlogoplre leuclte breccla, porphyrlrlc IanlDrolte, phlogou~te

Ill~ruslve breccla, sandv ieuclte-olivlne lamprolre ttttf massive hypa- byssal

Mass~ve. hypabvssai. Olivme lamvrolte. leuclre- veslcuiar lavas: mag- ~Illogoplte-diopside-11- maticautol~thic brec- chrerltelampro~re and cia, scorn, ruffs var~atlonn thereof

PH. CP, SP. T C

PH OL CP, AA SN, LC. ME PV. SP. AN

PH, OL, CP. LU. SP

LU. OL. PH. CP SP

PH. CP. AA, OL, LU; WD. PR. AP, BA. CC. SP. k PV. SH 3 a

DlOltZ Massme, hypabyssal Phlogo~!te-san~d8ne-am-

Dhgbole lanlnrolre

SN PN AA,RU, % AP, ZR MT

PH. SN. AA AP 3 Y

SN, RU BA F;: ZR MT QZ 25-

ri;: "" Asrn S (D

Cheiima, Indm (CHI3 1225 Praterozolc sedimen- Developed on Protero- Dvkes Masswe. metamor- Phlogo~l t~te PH. CC. SN C?; 3 rary and meramor- zolc Basln; Dhawar ~ h o s e a IL. MT E phic rocks craton basemen[

Coc-Pia, Upper Ton- Mesozorc Silurian conglomerare Marg~n ofstabilizeil Dvkes, lavas Mass~ve 'Coclte- PH, CP, LC. OL. 2 k ~ n , N Vietnatn cracon SN. ME, AN ( C O G

5

PH, phlogopste SE. sphene MN. montlcellite MZ. monaz~te 01,. olivzne LU. leuc~re/pseuaoleoctte ME. melilite SU, sulphide OP, orthopyroxene IL. iimenrre KS. Kalsiiire HE: hemat~te CP. clinopyr6xene ME; t~tanomagnetlte PR, priderlte PV, perovskite AA, alkali amphibole SP; chrome spinels WD, uzaaexre BA. barrte SN; sanidinelorthoclase NE. nepheline AN, analcime RU. anatase. rutile TR. tremolite PL, plag!oclase CC, carbohate (calcite. dolomite e t c j SII, shcherbakovtre

M

TABLE : Selecreii porossrc-~rlrra~ornsslc rock s~rrres cornposlrronn//y relnfed to lnmp~orres ,.- h,

~ o c a l ~ t y Age (Ma) Councry rocks Tecronic settmg Incrus~veIExcrusrve Texrural types Petlographlc types lmportanrm~nerals forms

Norrh nnierren Central Sierra Nevada

CA (CSN) 3.4-2.8 Mesozolc graniric rocks E Margln of Orogee Plugs, flows, pyroclas- Masswe. hypabyssal,

oithe Sierra NevZda t ~ s ves1~~11ar!avas batholili~

Ultranotasslc basan~tes as- CP. SN. PH. OL soc~ared with potasslcoli- LU. MT. RU vine basalts ana alkali AP basalts

Ol~v~oemelaleuc~txte, 011- CP,OL, PH LU, wnr leuc~te SN MT PL OP

AP

Deeo Sprlng Valley, CA (DSV)

7 2 Quaternarr,seatmen- tarv rocks, Jarassic granltes

Cylmdi~cal plugs Masswe, hypabyssal. locally ves~cular

PrOYlnCe 100 miles Eof Rocky

Mtn iron,-kont cra- ton margln

Highwooa. Bearpaw Sc Crazy Moi~ntains, MT(HM)

50-53 Nearly Bat-lylng Crera- ceous seannents SdndSlOneS. shales

Flows, plugs, dykes, Masswe. hypabyssai, piorons, sills. laccol- locally vesicular.

~ ths , lopolith brecclas, coarse-fine- era~ned narnlrvrrrlc

Shonk~nrre mtssourlte, CP, OL, PN. SN, mnfic phonolite. mlnette, NE, AN. LU. SP ainolte; Syenlte. m0112011- ,re

Limburgites, mlnettes. PH, CP, OL, SNI monchioitnes LU. AN, AP, GI

NE. MT, (ME. r\

KS) ' - 1

Biotite pyroxentres, isvlre. CP, PI-I. SN. NE. shonkinite. rnalign$te. ML, KS, SN;

tm 2

borolanlre, ioya~te, polas- MT, ZR, AP 09 kire

Yerlre (m%nette)-analclre PH. CP. OL. MT. 3 a

syenlte SN: PL. AN. 3

AA. AP

Coloraao Plateau Navajo-HOPI Buttes. AZ (NIID)

2-525-30 Mesozolc sedtmentary rocks

- Dyres, flows, necks. Masslve, hypabyssal,

pyroclastlcs vesxcular lavas. ruffs

Ilogntza rrend E Se- ward Pentnsola. W AK (SEN')

97-110 lurasslc-Creraceous MargrnoiPrecambr~an Stocks, pli~tons, dykes CG plurontcs, FG volcanlc pale craron of Seward Dykes

Pentnsula and Ruby Geanrlcline

Tert~arv Eocene Wasatch shales N of Colorado Plateau DvKe Massive Fartificatlan Dyke (FOR)

Two Buttes, CO (TB) Cenozolc Triasslc Red Beds W. margin Laccolith~ dykes Masswe N. Amer~can Craron

Cenozoic Pelitlc schisr,gnexss Appalachianorogen Plug, dykes Masslve

Prowerslre; sanidine-rich SN. PH, OL: CP, mmetle MT

M~nette SN. PH. AA. SN Knox County, ME IKNX) AP. Q, MT

Ezirooe Central Itnly(TUSC) Quaternary Roman co-magmnr~c Apennlde suba~lction Lava Bows, py~oclas- Flne-grdlned Por~hyrl-

DTOYIIICZ zone ~ I C S cmdercones I IC

Karunelres mafurtres OL. KS. LU. ME CP. PN. AP. PV SP. MN

OL, PH, CP, PL, SN AN. LU HM, AP

Channel Islands. Gaernsey & Jersey; Dcvonshire. U.K. (CkIN)

Bohe~ntan Masaii

280 Devonian-Permtan Hercvnlan orogen Lavas ruffs dykes Mass!ve, vesicular sedmentary rocks

Terttary Hercvnlan gramre and Palaeozo~c orogen Dykes Massive pluronlc rocks

PN; CP, SN, OL Czechoslovakia (BDFI)

Laachcr See. Etiei Provlnce F.R.G

bilocene- Hercyntan ana older Lare Cenozolc Rhlne Flows, pyroctasttcs, Mass~ve, scarla veslcu- Holocene crvsralllne rocks graben necks, cmdercones lar

Pldogoptre basanltes, leucl- CP, OL, PH, LU. tttes NE. MT. PL.

AP. SN

Sunnftord, Norway 258 Charnock>tes manger- (SUNNI ltes

Palaeozolc nappe aevel- Dykes onen and Precam- braan craton

SN. PH, AP. CO, BA. Rare

AI5,cn B~runga & Toro- Holocene- Archaean-Late Proter-

Ankole. Uganda Quaternary ozolc (TAN)

Azzaba. Algeria (AZZ) M~ocene Late Cretaceous flyscn

M' Branch. E African Cinder cones. lavas; rift pyroclastlcs

Mass8ve. vesgcutar scoria, <uffs, brecc~as

Katungltes. oiivme leucr- trte, leuc~te basan~res. rnelitxte basalis

Olivine iarnprotr~c trachyte

OP CP. LU. KS LU ME PH

OL SN CP PH, RU

Alulne moblte zone Dykes, flows, pyroclas- l lCS

Dykes, flows LU. SN. CP, PH AN. AP

h Batkal Riit-Aldan Shield. U.S.S.R.

L .

LU. SN, CP. PH. 3

'Q 3

NE 2 Y-,

m OL. PH. SN, LU,

- PL 5

EL

(BAL) Synnyr Mass)f 204-349 Felsic pli,ronlc rocks Murun Massif 115-143 Felslc DluIonlC rocks Inagll Massiv Cretaceous Felstc ~ t u r o n ~ c rocks

Gondwana Codlfields 105-121 Permian-Cretaceous E indm (Jhar~a Bo- rocks

R~ftea stable craton MarglnoiArchean Dykes

Stngbhom craron

Coarse and fine gralned massif

Massme

PH, AP. CC, SP. 3 v RU. SU. PR i;

3-

Carbonated apatjte gtlm- merlte

Sorrrh Aarencu Carnl~osde Jordao. SP 80 Precarnbrlan snleld

(CJ) Pledane SP (PD) 122 Precambrlanshield Sacratnenro MG 43

(SAC)

Stable craron Dykes

Stable craron Dykes DvKes. Lavas

Mdss~ve hypabyssal Tuffs blecclas mas-

swe, hypabyssal, In- rruslve brecclas

Volcanoclast~cs. rutis, masslve, hypabyssal

Sanro Anronla da Barra 85 (Rio Verde), GO (SAD)

Dykes. Lavas. Tulfs Ugandite

A~rrrrrrlrn Lake Cargelllgo ate8 10-14 Palaeozo~c seairnenrarv

(NSW) and votcanlc rocks Sxlurian-Devongan grantres

Central and Southern Dykes. flows, necks Highlands fold belt

LU, CP. OL, IL. PH: AA, AN. SN. NE. AP, CC. MT, PV

Abbreviations as ior Table 2

114 S C Bergmnn

FIG 2 World map showing the locations of lamproite renrii rtrxto suites and some of the compositionally-similar potassic--ultrapotassic lock suites For a mole complete listing, see Tables 2 and 3 and text

Hzlls Pond Kanras (HP) (37" 40' N, 95' 47 W/

Cretaceous (88 Ma (Zartman et a1 1967)) lam- proite plutons, sills and dykes intrude Precam- brian granites of the Rose Dome and nearly flat- lying Pennsylvanian shales and limestones near Hills Pond, Woodson County, SE Kansas (Twen-, hofel & Bremer 1928; Knight & Landes 19'32) (Fig 6 ) About 13 km SW of the Rose Dome, a 'mica peridotite' (madupitic lamproite (P Be[., endsen, personal communication, 1984)) of ap- proximately the same age (90-91 Ma (Zartman et a1 1967)) intrudes the Silver City Dome (Bickford et a1 1971; Franks 1966) The HP iocks possess all the earmarks of olivine lam- proites and consist of Ti-phlogopite, serpentin- ized olivine, K-richterite and Ti-diopside in a fine-grained groundmass of serpentine, perov.. skite, apatite and chrome spinel (Merrill et al. 1977) (Fig 4) Other petrological and geological contributions concerning the HP intrusives and their xenolithshave beenmade by Wagner (1954), Franks (1959, 1966), Franks et a1 (1971) and Cullers et a1 (1985) Fresh rocks have been recovered by drilling; the surface exposure of the HP body has been intensely altered to form a vermiculite body The petrogiaphy of madupitic (K-richterite-diopside) lamproites from the Sil- ver City Dome area are discussed in Berendsen et a1 (1985) Other lamproite diatremes occur in the area (H Coopersmith, personal communica- tion, 1985)

The geochemistry of the HP olivine lamproite is nearly identical to those of the diamondiferous olivine lamproites from Ellendale, Argyle and Prairie Creek Evidently, the quiescent intrusive character of the Hills Pond magmas, manifested by the preponderance of thin sills, was not conducive to the preservation of diamonds, assuming the magmas werederivedfromasimilar depth and source rock as the three diamondier.. ous suites mentioned The H P area is one of the rare occurrences in which lamproite forms well- developed sills and the only known occurr.ence of olivine-lamproite in well-developed sills

Holstelnrbo~g, W Greenland (HOL.) (66'45' N, 53" W )

Proterozoic lamproite (1200 Ma) and post-tec- tonic kimberlite (585 Ma) dykes (less than 1-2 m wide) intrude metamorphic rocks 1650-1 740 Ma old in the southern part of the Nagssugtoquidian mobile belt on the coast of central W Greenland (Noe-Nygaard & Rambert 1961; Escher & Watterson 1973 ; Scott 1977, 1979, 1981 ; Brooks et a1 1978; Thy 1985) (Fig. 7) The lamproites contain phenocrysts of olivine, diopside, K- richterite, Ti-phlogopite and pseudoleucite in a groundmass of Ti-phlogopite, diopside, K-rich- terite, sanidine, pyrite, a carbonate mineral and priderite (Fig 4), whereas the kimberlitescontain macrocrysts of olivine, phlogopite, picroilmenite and raie pyrope in a groundmass of olivine, Ti-

Lamproztes and K-rzch lgneolis rocks 115

FIG 3 Photographsof lamproite slabs showing typical rock textures (all listed clockwise from top left): (a) olivine lampioites from the Prairie Creek area (PRA) (American Mine, Kimberiite mine, Crater of Diamonds pipe (three samples) and Black Lick); (b) phlogopite lamproites from the Prairie Creek, Crater of Diamonds diatreme (PRA), all frorn the West Hill, showing tuffs and magmatic-autolithic breccias; (c) Fitzroy Basin (WKB) xenolithic/autolithic lamproite breccias (Mount Abbot, Big Spring, 81 mile vent, Mount Ibis, Calwynyardall Pipe and Fishery Hill; center; Ellendale pipe and Wolgidee Hill); (d) Fitzroy Basin (WKB) magmatic and volcanic rocks (Mount North phlogopitelamproite, vesicular 81 mile vent phlogopite lamproite, Ellendale pipe B olivine lamproite, vesicular 81 Mile Vent glassy phlogopite lamproite, altered near.surface Ellendale pipe B ; center glassy Oscar s Plug phlogopite lamproite); (e) Fitzroy Basin lamproites; (f') Leucite Elills lamproites (Scale: photograph a = 17 x 29 cm)

FIG 4. Photomicrographs (plane light) of various lamproites Massive magmatic Iamproites: (a) Wolgidee Hills wolgidite with perovskite, priderite, shcherbakovite, diopside, K-richterite in view; (b) Machells Pyramid Hill phlogopite lamproite; (c) Oscar Plug (WKB) glassy phlogopite lamproite; (d) Priestly Peak (PP) phlogopite lamproite; (e) Gaussberg (GSB) leucite lamproite; (f) Smoky Butte (SB) phlogopite lamproite; (g) Kamas (KAM) phlogopite lamproite; (h) Spring Butte (LH) phlogopite lamproite; (i) Holsteinsborg (5646) (HOL.); (j) Chelima (CUE) phlogopite lamproite Lamproite breccias: (k) Oscar Plug (WKB) lamproite-sandy tuff-breccia; (I) Boars Tusk (LH) phlogopite lamproite; (m) Argyle AKI (ARG) sandy tirK; (n) Calwynyardah (WHB) olivine lamproite. Olivine lamproites: (0) Hills Pond (UP); (p) Kimherlite Mine (PRA); (q) Black L.ick (PRA); (I) Crater of Diamonds (PRA); (s) Ellendale pipe B with dunite xenolith; (t) Ellendale pipe B with garnet xenocrysts Scale: each photograph is approximately 4 x 5 mm

phlogopite, apatite, diopside, serpentine, a car- of K-richterite-arfvedsonite-riebeckite-actinol.. bonate mineral, perovskite and spinel (Scott ite from related dykes Lherzolite, harzburgite 1977, 1979, 1981 ; Brooks et a1 1978) So-called and granulite xenoliths occur in the kimberlite 'anomalous' Iamp~ophyre dykes that are ex- dykes(Scott 1979, 1981) tremely rich in diopside with phlogopite, kaersu- The emplacement of the HOL lamp~oi tes is tite and titanomagnetite also occur (Scott 1977, broadly contemporaneous with the emplacement 1979, 1981) Thy (198?) reported an assemblage of the G a ~ d a ~ igneous province ((1 1--1 3) x 10)

Lnmproztes and K-rzch zgneous rocks

I

CRUSTAL AGES (BILLIONS OF YEARS) ULTRAMAFIC LAMPROPHYRE 1 = < 0 7 4 = l 5- 25 0 KlMBERLlTE LOCALITY i PROVINCE 2=07 -1 2 5=>25 A LAMPROITE LOCALITY 1 PROVINCE 3 = 1 2-1 5

A K-RICH BASALT i LAMPROPHYRE & OTHER - MAJOR CRUSTAL PROVINCE BOUNDARY ULTRAPOTASSIC ROCKS - -FRACTURE ZONE LAMPROPHYRE -.-. ---- SEAMOUNT CHAIN LINEAMENT * CARBONATITE

OR RIFT ZONE

FIG 5 Map of N America showing the locations of lamproite renru rrrioo suites, other K-rich rock suites, kimberlites, carbonatites and several notable lamprophyres Principal geological and tectonic features, i e Pacific oceanic crust fracture zones, the New England seamount chain, the mid-continental rift zone, the Colorado lineament zone, the inner boundary of Phanerozoic orogenic belts, the limit of areas presumed to be underlain by Archaean cratonic material and major crustal boundaries (with the approximate basement age after Condie 1976) are also shown For lamproite and K-rich rock suite abbreviations see Tables 2 and 3 and text Precambrian crustal provinces: Wy, Wyoming; CN, Central; GR, Grenville; SU, Superior : KA, Kaminak; SL, Slave; CH, Churchill Pacific fracture zones: ME, Mendicino; PI, Pioneer; MU, Murray; MO, Molokai; CL, Clarion Other features: NES, New England seamounts, CL, Colorado lineament: MCRS, Mid-continent rift system; OA, Ouachita fold belt

H

TABLE 4. Averag~ ( +standard dewntron) major-element composrtrons. Iamnpro~te and other rrltrapotass~c-potnsslc rock slrlres +. 00

Sum ,I SIO, T10, AI,03 FeO MtiO MgO CaO Na,O K,O P,05 H 2 0 + CO, Mgno K20!Na20 K,O!AL,O,

N Anrerrcn EVD HOL H P KAM I,H P R A SD (AIL) (CSNI (DSVI (FOR) (GAL.) iHMI ~ K N X ) INHE) (SEWI (SFC) (TD) (CHIN)

Arisrrniro WI(B ARG

Ezironr MAP NWI PEN MLM COR (TUSC) (SUNN)

A/rrcn BOB 1 52.5 5.9 8.6 7.2 0.01 10.2 2.1 0.2 10.4 ?.I 1.9 - 71.8 32.9 (PPS)

1.3 2 42.9 1.9 6.2 8.6 0.15 16.2 8.4 1.2 2.3 0.7 6.8 0.7

(TAN) 77.0 1.2

6 46.6 0.4

2.6 15.3 10.0 0.15 7.1 9.5 3.4 4.6 0.5 1.1 56.1 - 3

0.5 (AZZ)

0.9 2 58.4

0.3 !.4 13.2 4.9 0.08 8.9 >.J 1.5 7.8 0.3 2.3 - 76.5 - 2.- < 0.6

A,8rorcrrcn GSB 11 52.2 :.5 LO.! 6.1 0.09 8.2 4.7 1.7 11.9 1.5 1.2 0.1 70.3 4.6 MR AY 2 51.6 5.0 8.9 8.1 0.11 5.8 4.5 1.9 9.2 1.8 1.0

1.:

". PP 0 8 56.0 3.2 I . ?

4 51.2 ,.> 8.9 6.2 0.10 8.0 5.1 ' 1 . 1 8.8 :.I 0.8 0.1 70.0 6.1 1.1

Aslo & o,ilo,tesin COC 2 51.2 0.9 9.4 8.4 0.13 14.2 1 7 . . . 2.9 4.5 0.6 1.8 0.2 75.0 1 .O 0.5 CHE 2 41.1 6.4 5.2 9.2 0.10 20.7 11.5 0.2 2.9 2.2 3.1 10.0 80.0 71 ? ,.a GDW 4 44 T 4 5 h 5 9.7 015 15.5 12.1 0.6 5.8

0.6 0.7 2.8 4.8 74.1 5.8 L O b

o A n 19 < L 0 < ' I 7.6 0.6 - - 51.1 2.4 - 0.6

I 47.5 2.2 12.8 9.1 13.0 8.7 1.6 5. I - 3.6 - 71.9 2.0 0.4

n n, number oianalyses. Lamprolte sen211 rrrrcro sulres are In bold type; ultranofassic-~otasslc sultes are glven in parentheses. The malor elements [except H,O and CO,) have been normaiized to 2-

100% and a volatile-free basls (including BaO and ZrO,. which are gwen in Table 7). Mg number= LOO MgO/(Mg+FeO*! with rota1 Fe as FeO (aromlc untrs). See rext for abbrev~at~ons ana Appendix I for reierences. m,

0 z * Y :: 5-

S C Bergman

TABLE 5 Comparison of the average major..element compositions (wt %)of diamondiferous lamproites and Kimberlites with barren varieties

Known diamondiferous Known non.diamondiferous -- -- .-

Lamproites Kimberlites Lamproites Kimberlites -- - - SiO, 47+7 40+7 5 3 5 6 36+7 TiO, 2 9 + 1 2 4 + 1 7 3 1 + 2 3 0 + 2 A120, 4 8 + 1 5+2 10+2 5 + 4 FeO* 8 + 2 1 1 2 3 6 + 2 1 2 k 2 MnO 0 12+004 0 18+0 1 0 1OfO05 O20+0 1 MgO 23+6 2 8 k 7 10+4 27+8 CaO 8 i 8 1 0 2 8 6+ 3 13+7 Na,O 0 4 i . 0 3 0 6 + 0 9 1 6 + 1 0 6 2 1 2 KzO 7 5+1 1 5 + 1 1 7 5_1r3 1 4 + 1 pzos 1 3 + 0 7 0 9 + 0 8 1 3 + 0 7 0 9 + 0 8 BaO 0 9 + 0 8 O 1 9 f 0 2 0 6 + 0 6 0.16+0 1 CO, 4 + 4 4 0 + 5 1 7 + 2 8 0 + 5 H20t 3.3+2 7 + 4 3 + 2 5 + 3 Mg number 82+5 8 1 2 6 72+8 78+12 n 46 125 270 100

All oxides, except CO, and H20, are normalized to 100% on a volatile-iiee basis to facilitate comparison (see also Dawson 1986) n, number of analyses

Ma (Blaxland 1976a, b)) 700-800 km to the S of HOL, as well as a variety of alkaline complexes in Canada (Gittins et a1 1967; Currie et a1 1975), some of which contain pseudoleucite (Watkinson & Chao 1973), and the Kali 'kimberlitic' dyke in NSweden (Krestenetal 1977) Proterozoic((1 0- 1 2) x 10' Ma) potassic ultramafics in S Green- land (Upton & 'Thomas 1973) are similar in age and general geochemical character to the HOL. rocks, but do not fit the definition of lamproite It should be noted that diamonds have been recovered in kimberlites from the area between Ivigtut and Frederikshab (Andrews & Emeleus 1971) and in heavy mineral concentrates from stream sediments in the Fiskenaesset area (Niel- sen 1976) about 500-700 km S of HOL Over a dozen alkaline rock suites (carbonatites, lampro- phyres and kimberlites) occur in a coastal belt S of HOL and range in age from 2 65x lo3 to 0 12 x 10) Ma, indicating mantle-derived alka- line magmatic activity recurring in the same region for a time span in excess of half of Earth history (Larsen et a1 1983)

Kamas and Moon Canyon, Utah (KAM) (40" 40' N, I l l 0 12' W) Middle Tertiary dykes, flows and small plugs of phlogopite-olivine lamproites are spatially asso- ciated withmore syenitic dykes in Moon Canyon, near Kamas, Scott County, Utah (Fig 8) They occur near the junction of the W margin of the E-W trending Uinta Arch and the N-S trending Wasatch Mountains (Morris 1953; Larsen 1954; Best et a1 1968; Henage 1972) just W of the

Colorado Plateau Morris (1953) called the rocks melteigites and Best et a1 (1968) termed them wyomingites and orendites Phlogopite and oli- vine phenocrysts are set in a glassy groundmass of analcime, sanidine, phlogopite, clinopyroxene, K-.richterite, ilmenite, pseudobrookite, chromite, a roedderite-like phase and apatite (Wagner & Velde 1986a) (Fig 4) The dykes range in age from 1:3 to 40 Ma (Crittenden & Kistier 1966; Best et a1 1968) Henage (1972), on the basis of trace-element data on mineral separates and whole-rock dyke samples, established that the distribution of trace elements was heterogeneous as a result of both crystal separation and volatile- phase transfer According to Boutwell (1912), mica peridotite dykes were also intersected by underground mine workings in the nearby Park City mining district The KAM dykes and flows are located 250 km SW of the LH lamproites

Leucite Hills, Wyoming (LH) (41' SO' N, 109' 10' W)

The 14 Leucite Hills (22 major exposures) consist of cinder cones, lava flows, volcanic necks, dykes, intrusive sheets and pyroclastic rocks which were intruded through and extruded over Tertiary shales, Cretaceous limestones and clastic sedi- mentary rocks on the northern nose of the Rock Springs uplift in the Green River Basin, Sweet., water County, Wyoming (Fig 9) The LH are among the youngest lamproites (about 1 Ma old) (Bradley 1964; MacDowell 1966), second only to Gaussberg, and occur over an area of 2000--

Larnproztes and K-rzch zgneous rocks 1 2 1

90 Ma % HILLS POND LAMPROlTE

PENNSYLVANIAN @ SHAWNEE CARBONATES GROUP AND SHALES

DOUGLAS GROUP LANSING GROUP

a KANSAS CITY GROUP

-W iMo HILLS POND LAMPROITE

PENNSYLVANIAN DOUGLAS GROUP SHALES SAND- STONES

LANSING GROUP LIMESTONES

- FAULT - ROAD

HILLS POND LAMPROITE PENNSYLVANIAN

SEA SEDIMENTARY ROCKS LEVEL METAMORPHOSED -5W SEDIMENTARY ROCKS

and BB' based on drilling (after Wagner 1954j

2500 km' Cross (1897), Kemp (1897) and Kemp &Knight (1901) generated the nomenclature for LH that has since been applied to several other lamproite suites (Exeter area dykes, U K , K a mas, Utah, and Fitz~oy Basin, W Australia) More recent geochemical and petrological work includes that of Johnston (1959), Smithson (l959), Yagi & Matsumoto (1966), Carmichael (1967),

Kay & Gast (1973), Ogden et a1 (1978), Barton (1979), Ogden (1979), Kuehner (1980), Ogden et a1 (1980), Barton &van Bergen (1981), Kuehner et a1 (1981), Vollmer et a1 (1981, 1984), and Salters & Barton (1985),

Petrographic types (Cross 1897) include wyom ingite (leucite-phlogopite-diopside lamproite? olivine+K-richterite), orendite (leucite-sani-

PROTEROZOIC GNEISSES a METASEDIMENTARY ROCKS A R C H A E A N GNEISSES

8 P A L A E O Z O I C K I M B E R L I T E

PROTEROZOIC LAMPROITE I HOLl lCl8SBOli - FAULTS 4 ) @ DOME 0 -J ICO km

Fro 7 Generalized geological map oi W Greenland showing the relationship between lamproite and kimberlite intrusives and structural elements (After NoeNygaard & Rambert 1961; Scott 1977, 1981)

dine-diopside-phlogopite lamproite i: K-richter- ite) and madupite (diopside-.phlogopite l a m proite) (see Figs 3 and 4) The last mentioned is typically Si0,-undersaturated whereas the first two are often SiOz satu~ated or oversaturated Accessory phases include priderite, wadeite, apatite, perovskite, magnetite (rare), pseudo- brookite, spinel and Sr-barite (Carmichael 1967; Kuehner et a1 1981)

Experimental studies of LH rocks (Yagi & Matsumoto 1966; Sobolev et a1 1975; Barton 1976; Barton & Hamilton 1978, 1979, 1982) are summarized below

Lherzolite(rare), harzburgite(rare), pyroxenite and mica pyroxenite xenoliths occur at nearly all lamproite exposures (Ogden et a1 1978; Kuehner 1980; Barton & van Bergen 1981) and pa~ticrilarly in the volcanic necks Crustal xenoliths occur in the L.H lavas (Kay et a1 1978) Detrital Cr. pyrope, Cr-diopside and enstatite of ultimate mantle origin but unknown magmatic source (not the LH) have been found in ant hills W of the LH in the Green River Basin (McCandless 1982, 1984)

Crater ojDlamonds State Park and arroczated intluszue3, P~airre Creek, Murfieerboro, A~kanras (PRA) (34" 2' N, 91'40' W)

Although the diamondiferous Prairie Creek iutru- sions in the vicinity of the Crater of' Diamonds (COD) Park, Pike County, Arkansas, were previously thought to possess affinities with kimberlites (Miser & Ross 192.3; Scull 1959; Meyer 1976; Bolivar 1977, 1982; Lewis 1977; Meyer et a1 1977; Gogineni et a1 1978; Bolivar & Brookins 1979) it is now apparent that they have more larnproite than kimberlite affinities (Scott.Smith & Skinner 1982, 1984a, b, c; Mitchell & L,ewis 1981; Bolivar 1984) Note that Carmichael et a1 (1974, p 517) were arguably the first to suggest this feature The COD lamproite is a 71 acre diatreme with three different lithological units: a massive hypabyssal olivine- phlogopite lamproite, an intrusive/extrusive vol- canic breccia and a phlogopite lamproite tuff (Figs 3, 4 and 10) Only the breccia is presently believed to contain an economic concentration of diamonds, although the three lithologies have not been tested using modern techniques At least four other associated lamproite int~usions occur 1-3 km to the NE of COD: the Kimberlite mine, the American mine, Twin Knobs and Black Lick prospect All are diamondiferous except for the last,

The PRA intrusion was first mentioned by Powell (1842; cited by Miser & Ross 1923) and received early attention as a micaceous peridotite (Branner& Brackett 1889; Williams 1891) Miser & Ross (1923) were perhaps the first to put the PRA intrusive into the geological context of the better-studied diamondiferous peridotites of southern Africa, even though diamonds were initially discovered at COD in 1906 Additional studies of the geology, geochemistry and miner- alogy of the PRA rocks include those by Miser & Purdue (1929), Ross et a1 (1929), Moody (1949), Thoenen et a1 (1949), Stone & Sterling (1964), Grego~y (1969), Gregory & 'Tooms (1969), L.ewis et a 1 (1976), Meyer (1976), Brookinset a1 (1979), Steele & Wagner (1979) and Waldman et a1 (1985) PRA diamonds and their mineral inclu- sions have been the subject of many studies (L.angihrd 1971; Giardini eta1 1974; Giardini & Melton 1975a, b, c) as have been their occluded and included gases (Melton et a1 1972; Meiton & Giardini 1976, 1980) Roedder (1984, p p 509- 10) disagreed with the interpretations made in the last three studies.

The PRA lamproites intrude the nearly hori- zontallower Cretaceous'Trinity Formation (clay, silt, sand, gravels and limestones); peridotite pebblesoccur at the base of the IJpper Cretaceous

Lamproltes and K-rzch zgneolis rocks

QUATERNARYOSEDIMENTARY ROCKS

TERTIARY b LAMPROITES

SEDIMENTARY ROCKS OANDESITIC PYROCLASTICS

M E S O Z O I C ~ S H A L E S SILTSTONES, SANDSTONES

PALAEOZOIC@CARBONATE ROCKS, SANDSTONES A N D SHALES

PRECAMBRIANESHALES A N D QUARTZITES

OR SUGGESTED

FIG 8 Generalized geological map of the W Uinta Mountain area, Utah, showing the geological position of the Kamas and Moon Canyon lamproites (After Best et a1 1968; Henage 1972; Hintze 1980 )

Tokioformation(Miser&Purdue 1929) Zartman Leucite- and pseudoleucite-bearing intrusions (1977) and Gogineni et a1 (1978) suggest an age (syenites and tinguaites)cut nephelinesyenites at of intrusion of 97-106 Ma on the basis of K-Ar Magnet Cove, Arkansas, 90 km NE of PRA dating of phlogopite separates The PRA intru- (Williams 1891); lamprophyres are widespread sions occur on the margin of the Ouachita fold in the Ouachita Mountains (Robinson 1976; belt on the northernedge of the Gulf coastal plain Mullen & Murphy 1985; Mullen & Petty 1985) (Wickham ct a1 1976)

The hypabyssal and brecciaphases of the PRA Smoky M~~~~~~ (SB) (47" l y ~ , 1 0 ~ .y W ) intrusions consist of olivine ~henocrvsts (often

serpentinized) in an extremely fine..grained groundmass of phlogopite, serpentine, perov- skite, K-richterite, Cr-spinel, magnetite, d i o p side, wadeite and priderite (Figs 3 and 4) The epiclastic tuff unit (Scott-Smith & Skinner 1984a, b, c) contains abundant phlogopite, sanidine and quartz in an extremely altered clay-chlorite-- carbonate matrix Both the breccia and tuff'units contain abundant autolithic and xenolithic (sedi- mentary rock) fragments Garnet (pyrope and almandine) is extremely rare and typically only encountered in heavy-mineral concentrates; pi- croilmenite only occurs as inclusions within garnets and as extremely rare xenocrysts Coarse grained lamproite xenoliths consisting of K- richterite, phlogopite, diopside and priderite from the massive hypabyssal facies have been described by Mitchell & Lewis (1983)

N-NE..trending dykes and small plugs of l a m proite intrude the Tullock member of the Palae- ocene Fort Union formation (sandstone and shale) along the axis of a very broad gently- dipping regional syncline over a distance of 3 km just W of Jordan, Montana (Matson 1960) (Fig 11) The three major rock types at SB contain the following mineral assemblages in addition to glass: (i) sanidine, K-richterite, K-riebeckite and armalcolite; (ii) 'Ti-phlogopite, diopside, olivine, sanidine and armalcolite; (iii) Ti-phlogopite, diopside, olivine, analcime and armalcolite (Velde 1975; Matson 1960) Velde (1975) noted the presence of priderite and Wagner & Velde (1986a) additionally recognized pseudobrookite and chromite D Velde (personal communica- tion, 1985) noted the presence of a new mineral, davanite (K,TiSi,O,,), in the SB rocks

124 S (3 Bergman

0 10 20 km (1 1-1 2 MaJ~LEUCITE-PHLOGOPITE LAMPROITE u P A ~ A E O C E N E FORT UNION FORMATION

EOCENE - GREEN RIVER WASATCH FM u CRETACEOUSDLANCE SANDSTONE 8 SHALE

aL.EWlS SHALE @ALMOND SANDSTONE & SHALE BERICSON SANDSTONE

ROCK SPRINGS SANDSTONE 8 SHALE

B E L A I R SANDSTONE BEAXTER SHALE

FIG 9 Generalized geological map of the northern Rock Springs Arch of the Green River Basin showing the location of the Leucite Hills lamproites: BT, Boars T'usk; MAT, Matthew; SM, Steamboat Mountain; BR, Black Rock; OR, Orenda; BAD, Badgers'Teeth; ZIR, Zirkel Mesa; EM, Emmons Mesa; HAT, HatchesMesa; HAG, Hague; HAL, Hallock; END, Endlich; NP, North Pilot Butte; N'T, North Table Butte; ST, South Table Butte; CR, Cross; OS, Osborn; P, Pilot (4fter Cross 1897; Kemp & Knight 1903; Love er ai 1955 )

The dykes are generally extremely fine grained to glassy in texture and often contain zeolite or carbonate-filled vesicles, but massive coarse- grained (1-2 mm) type (ii)lamproite withresidual groundmass glassoccurs at the Smoky Butte plug Bedded weld& autolithic lamproite lapilli and piperno (welded agglutinate tuffs) in clay-rich matrices overlie and are marginal to the intru- sions Contact intrusive breccias composed of vesicular deformed magmatic lamproite f'rag- ments in a clay-rich matrix also occur at the plug and are almost identical with the breccias observed at LH, WKB, MAP and in other lamproite suites (S C Bergman, unpublished data)

Mitchell & Hawkesworth (1984) discussed the trace-element and NdrSr isotopic geochemistry of the SB intrusions On the basis oi'K-.As dating (Marvin et a1 198D), the SB intrusives are 27 Ma old, relative to the 47-51 Ma ages of the Winnett alnoite (100 km WSWof SB), the Missouri Breaks kimberlites and ultramaficlamprophyres(l60 km WNW of SB) (Hearn 1968, 1979; Hearn & McGee 1982,1984), and the HighwoodMountain shonkinites and minettes (300 km W of SB) Sapphire-bearing minette-like lamprophy~es oc.. cur at Yogo Gulch in ceritral Montana (e g Meyer &Mitchell 1985) Aithoughonly obscurely described in the literature, dykes whose o c c u ~ ~ rence and mineralogy are similar to that of SB

Lamproltes and K-rzch zgneous rocks

OUATERNARY ALLUVIUM OUATERNARY fl TERRACE

GRAVELS UPPER TOKIO

CRETACEOUS FORMATION

MIDDLE LAMPROITE CRETACEOUS (-106 Mo)

LOWER a TRINITY CRETACEOUS FORMATION

CARBON- JACKFORD IFEROUS SANDSTONE

QUATERNARY n ALLUVIUM - u C R E T A C E O U S ~ ~ MASSIVE

HYPABYSSAL OLIVINE LAMPROITE

a LAMPROITE BRECCIA

fl PHLOGOPITE LAMPROITE TUFF i AGGLOMERATE

L CRETACEOUS OTRlNlTY FM CA RBONI FEROUS~ JACK FORK

SANDSTONE

Frc 10 (a) Generalized geological map of the Murfreesboro atea, Arkansas, showing the positions of lamproite int~usives at Prairie Creek, Twin Knobs, Kimbeilite Mine, Black Lick and American Mines; (b) generalized - i p I I ! : : I : I p 1 1 1 : E - - \ V :il)js-,L.CilonS01 ih: P I~ : I : c C'ICCL 1.1npr ~ 1 1 i

J:SLIC~IL. i k a w l n ~ i:\,o 'i:telnnr!\6 I~IL':?~CI.~!JII, ! C I I n:l:ioi ~!:;:!.I:I? 3!'i~': HsII\ R I 1)":

1 2 6 S C Bergman

0 ULTRAMAFIC LAMPROPHYRE OR KlMBERLlTE ALKALIC ROCK PROVINCE

PALAEOCENE n FORT UNION FORMATION (SHALE. SILTSTONE SANDSTONE)

U. GRETA. BHELL CREEK a CEOUS FOX HILL SANDSTONE

1SANDSTONE MUDSTONE)

BEARPAW SHALE

JUDITH RIVER, CLAGGETT EAGLE SANDSTONE TELEGRAPH CREEK FORMATIONS (SHALES - SANDSTONES)

AFTER MATSON (7WI

&L.AMPROITE DYKE, PLUG -CREEK (INTERMITTENT)

28W' CONTOUR - -DIRT ROAD

SMOKY BUTTE LAMPROITE NE 'A TIEN, R36E

GARFIELD COUNTY MONTANA

FIG 11 (a) Map of Montana showing the locations of the Montana petrographic province alkaline rock suites (after Larsen 1940; Hearn 1979; Marvin et ai 1980) (LBM, Little Belt Mountains; HB, Haystack Butte; HM, Highwood Mountains; CAM, Castle Mountains; CZM, Crazy Mountains; BBM, Big Belt Mountains; MR, Madison Range; GM, Gallatin Mountains; ABR, Absaroka Range; SEf Sweet Grass Hills, Haystack Butte, East Butte; BPM, Bearpaw Mountains; RB, Rattlesnake Butte; TB, Twin Butte; L.RIM, Little Rock Mountains; MBD, Missouri Breaks Diatremes; SB, Smoky Butte; ID, Ingomar Dome Diatreme (Fioze.to-Death Butte); PD, Porcupine Dome; WA, Winnett Alnoite; JM, Judith Mountains; MM, Mocassin Mountains); (b) generalized geological map of NE Montana showing the geological environment of the Smoky Butte lamproite intiusives and extrusives (after Ross er a1 1955); (c) geological map of the Smoky Butte intrusives and extrusives (aftel Matson 1960)

Larnprolte~ and K: -rzch zgr~eous rocks 127

occur in Rosebud County, Montana, 90-100 km S of SB at TlON,R36E, near the Ingomar Dome at Froze-to-Death Butte (Heald 1926, pp 26-7; Marvin et a1 1980) and at TION, RME, on the Porcupine Dome (Bowen 1915, p 66) The well.. described igneous r:ocks geographically closest to SB are those of the Winnett alnoite sill (Ross 1926a; Marvin et a1 1980)

[Nuuajo-Hopz Butter, Atzzona ( N H B ) (35" 25' N 110" W ) ]

Dykes, flows, volcanic necks and pyroclastics of potassic and ultrapotassic mafic melts were erupted through Triassic and Cretaceous sedi- ments in two intervals (2-5 and 25-10 Ma ago (Roden et a1 1979)) in the Four Corners area on the SW part of the Colorado olateau (Williams 1936; ~ n d e r s o n et a1 1970; Roden 198i, Rogers [CentralSletrahreuada. Ca:aiiSorn~a ( C S N ) 137'

1982) The Navajo rocks are potassic 7O'N 710' 10' W i l - - - . , A A , - , 1 1 , , whereas the Hopi Butte localities tend to be sodic

Ultrapotassic basanitic lavas and plugs (free of These rocks are not lamproites senru strict0 plagioclase) and associated potassic olivine and becausethey haveatomicK20/Na20= 1 .3,K20/ alkali basalts (plagioclase bearing) were erupted AI20,=0 1 and their phlogopites contain 12- from 3 3 to 1 8 Ma ago through the core of the 15 5 wt % A1,0,; however, the presence of Sierra Nevada batholith (Van Kooten & Peck analcime-bearing minettes suggests that lam- 1977; Van Kooten 1980; Dodge & Moore 1981). proites may occur as end-members of the suite These rocks posses!; atomic K / N ~ and KIA1 ratios, MgO contents and Rb contents which are too low and CaO and Na,O contents which are too high to be lamproites 'The phlogopites and diopsides of CSN lavas are richer in A1 than are those of lamproites Although the BaO contents of CSN lavas are extreme (0 3-0 6 wt %) and similar to those of lamproites (0 6 wt %), the Rb levels are extremely low (less than 100 ppm) for lamproites (typically 200-300 ppm)

[Deep Springs Valley, Calfotnra (DSV) (37' 21' N 118°03' W ) ]

Four leucite-bearing mafic, olivine melaleucitite, olivine-leucite trachybasalt and potassic basalt plugs and flows (Dodge & Moore 1951) contain plagioclase and have whole-rock K,O/Na,O and K2O/A1,0, atomic ratios too low to be lam- proites

[Hzghwood Mountams Montana ( H M ) (47' 31' N 110" 48' W ) j

The Highwood Mountains sub-province (Larsen et a1 1941 ; O'Brien et a1 1985) displays the best- developed suite of' potassic-ultrapotassic mafic alkaline rocks (see Fig 11) of any suite within the alkaline petrographic province of central Montana (Weed & Pirsson 1895; Buie 1941; Larsen 1940) The HM rocks occu~ as flows, plugs, dykes, plutons, sills, lopoliths and laccoliths and wire emplaced 50-53 Ma ago (Marvin et a1 1980) about 160 km E of the Rocky Mountain front Petrographic types of interest include nepheline-,normative shonkinite, missou~ite and minette (mafic phonolite) The HM rocks are not as perpotassic (K,0/A120, = O 4) or ultrapotassic (K,O/Na,O-1 5 ) as typical lamproites (Tables 4 and 5)

[SewatdPenznsula, Alaska ( S E W ) ( 6 P N, 116" 10' W ) ]

A belt of alkallne rocks 350 km long trends NE from the Darby Mountainsof the easternseward Peninsula to beyond the Kobuk-Selawik low- lands 200 km to the NE (Mlller 1970,1972) The complex 1s middle Cretaceous in age (97-1 10 Ma) and consists dominantly of peraluminous potassic nepheline syenites and related rocks with aminor component of peraluminous ultrapotassic rocks As shown by Miller (1972), the SEW rocks are nearly identical, in terms of both mineralogy and geochemistry, to the HM suite, Montana Some of the SEW rocks are extremely ultrapotassic, and contain among the highest K 2 0 contents of igneous rocks recorded in the world because of the abundance of kalsilite (atomic K,O/ Na,O= 13, 16 6 wt % KzO: Kobuk Selawik Lowland juvite) (Miller 1972)

[Fortficatzon dyke, Colota~io ( F O R ) (40" 48' N 107' 40' W ) ]

Ross (1926b) described a dyke 16 km long (3-6 m wide) trending N60°W about 10 km N of Craig, Colorado, that contains a majority of oligoclase and orthoclase with minor mafics The FOR dyke, though originally termed 'verite' by Ross (1926b), is not a lamproite because it contains sodic plagioclase and consequently has low K,O/ Na,O and K,O/Al,O, ratios The present author classifies the Fo~tification dyke as alamprophyre, but modern diagnostic mineral and chemical studies are needed to say anything further

128 S C Bergman

(IwoBzitter, Colorado(i"B) (37' ?0'N,102°30' W ) ] group ( c j Rock 1986), recent work has demon- strated the existence of priderite in some of the Cenozoic laccoiiths and associated dykes of 'minettes' (K. Collerson, personal communica- prowersite at Two Buttes in the Arkansas Valley tion, 1984j detailed is therefore

(Gilbert 1896; Cross 1906) are minettes even to establish the of the AIL though they were originally included in Niggli's

lamproite clan Despite an ultrapotassic geo. dykes, although it is possible that true minettes

chemistry (atomic K,0/Na2C)=5), A120j con- may carry priderite

tents (12 3%) are slightly high f o ~ lamproites Although the analysis may be suspect, the A120, [Ch~no Valley Arzzona (CHIN) (3S0N 112' 30'

content of' an augite separate is 3 I wt % (Cross w ) 1 1906), which is much too high for lamproites (see A 25 Ma old eclogite-. and peridotite-xenolith- below) bearing potassic latite (55-60 wt % SiO,, atomic

K 2 0 / N a 2 0 = 1-3 and 4-5 wt % MgO) and potas- [K~~xCoun~~,M~~neI~N~)(44"I~'N.69~10' W)1 sic felsic latites occur at Sullivan Buttes, neaI

Prowersites from Appleton Maine (Bastin 1906) Chino Valley, Arizona (Arculus & Smith 1979;

contain large phznocrysts of perthitic feldspars. Rodenet a1 1979; Schulze & Helmstaedt 1979)

Despite a low A1,0, content (10 6 wt %) and an ultrapotassic character (atomic K,O/ [Colima Graben, Me.xico (COL) ( 1 9 O 40'N,

Na,O=? 5), the KNX rocks are not lamproites 40' W ) ] or even lamprophyres

[Galore C~eek , British Columbza (GAL) (57" 14' N, 131" 30' W ) ]

lJltrapotassic pseudoleucite-bearing syenite por- phyries and phonolites occur in the upper Galore Creek Valley, NW British Columbia (Allen et a1 1975) Although altered with abundant evidence for orthoclase replacement, these peraluminous rocks contain elevated K 2 0 contents (9-17 wt YJ and atomic K 2 0 / N a 2 0 ratios (about 3)

[Spotted Fawn Creek, Yukon (SFC) (64" 22' N, 133" 42' W ) ]

Pseudoleucite-bearing tinguaites (coasse.grained phonolites occur in the Spotted Fawn Creek ar.ea in W central Yukon (Templeman-Kluit 1969) The rock is ultrapotassic, yet metaluminous with atomic K , 0 / N a 2 0 = 3 1 and K,O/AI,O, = 0 7

[A~llikBay, Labrado~ (AIL) (59'1 S W , 5T015'N)]

Late-Quaternary K..rich basalts, andesites and related rocks occur in the Colima Graben of the E-W-trending Mexican volcanic belt (Luhr & Carmichaei 1980, 1981) These workers have described phlogopite-bearing K-rich basalts which are petrographically similar to minettes

[Other K-rrch rock localztzer]

Brief descriptions of other occurrences of N American K-rich rocks can be found in Glazner &Stork (1976), Shafiqullah et a1 (1976), Glazner (1979), Rowell & Edgar (1981), and references cited therein

Australia

In contrast with the widespread occurrence of diamonds and kimberlites in Australia (Fig 12), lamproites sensu strrcto only occur along the SW and SE flanks of the Kimberley craton in NW Australia The leucitites of New South Wales are

Minette dykes occur as part of the Mesozoic not included in the lamproite clan in this papel

mafic-ultramafic lamprophyre-carbonatite suite because of their anomalous character The

of Aillik Bay, Nain Province, Canada (Hawkins Terowie, S Australia, 'lamproites' reported by

1976; Foley 1982, 1984) These dykes intrude Colchester (1982, 1983) are also interpreted as

Archaean gneisses and Proterozoic metavolcan- olivine nephelinites ( C a ~ r & Olliver 1980; S C

ics and metasediments and include the following Bergman, unpublished data)

petrographic types m~nette, monchrqulte, al- WKrmberleys, W Aurtralra ( W K B ) (18ON, 124' nolte, aillrklte and carbonatite Although the .., , ,

heretofore understood geochemistry and petrog. Y , J C)

raphy (Kranck 1953; Hawkins 1976) of the AIL Over 100 individual occurrences of many petlo- 'minettes' (6% olivine, 35% augite, 28% biotite, graphic types of lamproite sensu rtrzcto flows, 25% orthoclase and 4% oxide; 44% SO2, 4 0 wt % plugs, dykes, plutons, sills, diatremes, crypto- TiO?, 9 1% AI,Oj, 11 0% FeO*, 10 5% MgO, volcanic structures, tuffs and other pyroclastics 7.5% CaO, 6 3% K 2 0 , 18% Na,O, 1 1% P 2 0 , ) occur on the margin of the P~oterozoic King displayed characteristics typical of minettes as a Leopold mobile zone, the Fitzroy Trough and the

Lamprolte~ and K-rich Igneous rocks 1 2 9

PROTEROZOIC FOLD BELTS

C RIFT VALLEY - CONTINENT-OCEAN \ BOUNDARY ( M a )

-- FRACTURE ZONE - 1- EXTRA-ARCH BASIN

DIAMOND OCCURRENCE

A ULTRAPOTASSIC ROCK KiMBERLlTE

Q ULTRAMAFIC LAMPROPHYRE CARBONATITE

FIG 12 Generalized map of Australia showing the major Archaean cratons, Proterozoic mobile zones, continent-ocean boundarv. oceanic crust fracture zones (and other features) and the locations of lamnroites. kimberlites, carbonatites,2"ltramafic lamprophyres and diamond occusrencks (After Gailick 1979, 1$83; ~Gacke era1 1979; Veevers 1981; Atkinson et a1 1984a)

Lennard Shelf (in three separate fields-Ellen-, dale, Calwynyaidah and Noonkanbah), all of which form the Canning Basin on the SW flank of the Kimberley Basin (Fig I?) Diamonds occur in over 30 separate intrusions (Atkinson 1982; Atkinson et al. 1984b) These intrusions were discovered by Fitzgerald (1907), initially petrographically and chemically described by Simpson (1925), Farquharson (1920, 1922) and Skeats&Richards (1926), and have since received considerable attention in detailed work by Wade (1937), Prider (1939, 1960, 1965, 1982), Wade & Prider (1940), Prider & Cole (1942), Bell & Powell (1970), Derrick & Gellatly (1972), Mason (1977), Atkinson et a1 (1982, 1984a, b), Jaques et a1 (1982, 1983, 1984a, b), Nixon et a1 (1982, 1984), McCullochet a 1 (1983a, b), Smith (1984a, b) and Jaques et a1 (1986) Although eu ly K-AI and Rb-Sr work erroneously indicated ages of 15 Ma and 250 Ma respectively for WKB rocks (Prider 1960; Kaplan et al. 1967), more recent K-AI and Rb-Sr work on mineral separates limits the age of emplacement of 14 of the WKB lamproites to 17-25 Ma (Wellman 197:3; Jaques e ta1 1984a; Bergman & Onstott, unpublished data) This ultrapotassic and perpotassic suite consists of a petrological continuum from diamondif'erous olivine lamproites to barren leucite lamproites (Atkinson et a1 1983,1984a; Jaques et a1 1984b,

1986) The WKB olivine lamproites contain olivine megacrysts and aggregates in a fine- grained to glassy groundmass of olivine, phlogo- pite, diopside, apatite, K-richterite, perovskite, wadeite and spinel, whereas theleucite lamproites are composed of phlogopite, diopside, K-richter- ite and leucite phenocrysts in a groundmass of several of the above phases with spinel, wadeite, priderite, jeppeite, shcherbakovite, perovskite, apatite and rare ilmenite (Figs 3 and 4) K- f'eldspa~ is absent except where it replaces leucite Wade & Prider's (1940) nomenclaturefoiindivid~ ual rock types is summarized in Table 1

The WKB lamproites occur on the southern margin of the Precambrian Kimberley block and intrude mostly Mesozoic and Palaeozoic sedi- ments, although a few intrusions cut Proterozoic granitic rocks The regional structure consists of dominantly NW-trendingfaults withE-W-trend- ing anticlines and subordinate synclines oriented in an en echelon pattern

Mantle xenoliths are rare in WKB rocks but include dunites and harzburzites (Atkinson et a1 1984a; Jaques et a1 1984b, 1986) Many of the olivine-rich xenoliths display features similar to the aggregates with smaller olivine grains. Hall & Smith (1985), Jaques er a1 (1986) and Smith (1984a) discussed aspects of the ARG and WKB diamonds

130 S (7 Bergman

CRETACEOUS CANNING BASIN SEDIMENTARY ROCKS

TRIASSIC SEDIMENTARY ROCKS

PERMIAN C] SEDIMENTARY ROCKS

DEVONIAN H REEF CAR80NATES KIMBERLEY BASIN SEDIMENTARY ROCKS LARCHAEAN EASEMENT)

. PROTEROZOIC KING LEOPOLD MOBILE ZONE

LEUCITE LAMPROITE OLIVINE LAMPROITE - FAULT

....... ANTICLINE OR

SYNCLINE

UMAGMATIC LAMPROITE COARSELY MICACEOUS 0 I km

MAGMATIC LAMPROITE I__-

FINELY MICACEOUS

0

CROSS .SECTIONS

OMAGMATIC LAMPROITE aMUDSTONE

OTUFF

FIG 13 (a) Generalized geological map of the Canning Basin and King Leopold Mobile Belt, W Australia, indicating the locations of olivine and leucite lamproite intrusives (after Bureau of Mineral Resources, Geology, Geophysics 1976; Atkinson er a 1 1984; Jaques er a1 1984a); (b) geological map and cross-sections of the Ellendale olivine lamproite diatreme, Lennaid shelf (after Atkinson et a1 1984a); (c) geological map and cross- section of the Calwynyardah olivine lamproite diatieme, Fitzroy 'Tiough (after Atkinson er a1 1984a; Madigan 198:3)

L,amproites and K-rich igneous rocks 131

Argyle, E Kimberleys WAustrnl~a (ARG) (16' Creek moblle zone at Llssadell Road and Bow 40'S, 128' 25' E ) Hlll (Atklnson et a1 1984a, b, Jaques et a1 1986)

The diamondiferous Arevle AKl olivine lam- ", proite pipe is located on the eastern flank of the Kimberley craton in the 1940-1800 Ma old Halls Creek mobile zone (Atkinson et a1 1982, 1984a, h ; Madigan 1981; laques et a1 1986) This intrusive is 125 acres in exposed area and is the richest diamond deposit in the world in terms of grade, containing proven reserves of 61 million tons at 680 ct per 100 tons and additional probable reserves of 14 million tons at 610 ct per 100 tons (Atkinson et a1 1981b) (Fig 14) An extensive alluvial diamond deposit also occurs adjacent to the Argyle pipe in Smoke Creek and Limestone Creek(Madigan 1983; Meakins 1981) The ARG intrusive is most probably Precambrian in age since it is overlain by Cambrian sediments; it consists predominantly of an olivine lamproite sandy tuff that is intruded by dykes of magmatic olivine lamproite The massive magmatic phases consist of euhedral olivine phenocrysts (replaced by talc and carbonate) and ragged tetraferriphlo- gopite microphenocrysts in a fine-grained ground- mass of phlogopite, anatase, sphene, pesovskite, apatite, Mn-ilmenite, Ti-Mg chromite and sul- phides (Fig 4) The sandy tuff is massive or weakly bedded and contains magmatic lamproite clasts in a groundmass of olivine, ash and xenolithic rounded quartz grains(Fig 4) L.eucite has also been reported in the ARG rocks Dykes of mica peridotite occur near ARG in the Halls

[Lake Cargeil~go Area, New South Wales ( N S W) (33" 2 V S , 146' 2 7 E ) ]

L.eucite-bearing lava flows and associated scoria cones and pyroclastics were erupted from 10 to 15 Ma ago (Wellman et a1 1970; Cundari et a1 1978) through a peneplaned basement complex of Palaeozoic geosynclinal sediments and granites and an overlying thin veneer of Cenozolc sedi. ments of the central and southern Highlands Fold Belt over a 450 km x 150 km belt with concentra- tions near Lake Cargelligo, New South Wales (Cundari 1973; Cundari & Ferguson 1982, and references cited therein) The NSW essential mineralogy consists of diopside, olivine, leucite, Fe.Tioxides, Ti-phlogopiteand Ti-richteritewith accessory apatite, sanidine and rare nepheline Although the essential minerals of lamproites are present in the NSW rocks, their compositions deviateslightly fromlamproiteswith Ti-richterite intermediate between the Na and K end., members (K,O/Na,O=O 8-3 0 (weight basis)) and high A1?0, contents of 1 7-2 4 wt %; diopsides addltlonally possess a wide range in Al,O, contents (as high as 2 8 wt %) However, compositions of some phlogopite and diopside phenocryst cores possess typical lamproite char- acteristics with extremely low A1,0, contents (9 7 wt %and 0 09 wt % respectively)

- PLAN L-----l CROSS-SECTIONS

FIG 14 Generalized geological map and cross-section of the Aigyle AKI olivine lam5 Creek mobile zone (Aftel Madigan 1983; Atkinson et a1 1984~)

a LAMPROITE- NON SANDY TUFF

U LAMPROITE- SANDY TUFF

- FAULT

xoite diatreme, Halls

S C B

Although the low CaO, AI,03 and Na,O contents of the NSW rocks are typical of lamproites (average of 28 analyses, 9 0 wt %, 8 7 wt % and 1 8 wt %respectively), the average atomic K 2 0 / N a , 0 ratio of 2 1 and atomic K 2 0 / A1203 ratio of 0 6 are rather low for lamproites TiO, contents in the NSW rocks are extremely high (range of 3 4-8.0 wt %; mean, 4 3 wt %) for lamproites (mean, 2 8 wt %) 'The average Mg number of the NSW rocks (66) is somewhat low for lamproites (average, 74) 'The Sr--Nd isotopic compositions of' NSW rocks are anomalous in that they plot close to bulk Earth instead of' well within the 'enriched-Sr, depleted.Nd mantle quad~.ant' as other lamproites on a '43Nd/114Nd versus 87Sr/86Sr plot (R Mitchell, personal communication, 1984) The NSW rocks are theiefore not considered lamproites rensu strict0 because of' their major-element geochemistry, isotope geochemistry and mineralogy They are closely allied, however, to the lamproite clan

[Mordor complex Central Aurtralza ( M O R ) (23" 32 S, 134" 27' E ) ]

The ultramafic to felsic rocks of the Mordor complex in central Australia (Langworthy & Black 19'78) are potassic to ultrapotassic (atomic K,O/Na,O = 2--5) and mildly peraluminous (molar (K,O + Na,0)/A1,03 = 0 3-0 6) and are therefore not lamproites

Europe

Post-tectonic lamproites rensu rtricto occur in at least four districts in Europe: in the EIercynides of Cornwall at Pendennis Point, in the Appenides of SE Spain between Murcia and Almeria, in NW Italy and in an isolated occurrence on the island of Corsica Potassic to ultrapotassic non- lamproite rock suites characterize the Meditei- ranean area, the most notable being the strongly peraluminot~s central Italian volcanic province, but also including the Permian Exeter volcanics and Channel Island dykes of the U K , the Bohemian Massif' in Czechoslovakia, the Anato- lia province of 'Turkey, the Spednogorie Zone, Bulgaria, the Hellenic arc in southern Greece, the Aeolian arc, southern Italy, and isolated occurrences in Iran and Norway Interestingly, both the lamproites and compositionally similar potassic to ultrapotassic rocks of Europe are generally depleted in 'Ti and Nb (about 1-2 wt % TiO, and less than 40 ppm Nb) relative to these rock types fiom most other worldwide localities (2-5 wt % TiO, and more than 50 ppm Nb) These compositional features of 'Ti and Nb depletion are shared by subduction-derived ba-

salts and andesites (Ewart & L.eMaitre 1980; Gill 1981; Briqueu et a1 1984) and will be discussed in more detail below Note that minettes are widespread throughout Europe (Velde 1969b)

Murcia-Almer ~aprovinte, S E Spain (MAP) (?ao 30' N, lo 19' W )

Breccia-mantled pipes, plugs, sills, flows and tephra of lamproite were emplaced through Mesozoic and Tertiary sedimentary rocks from 6 to 8 Ma ago (Bellon & L.etousey 1977; Bellon 1981; Bellon et a1 1981 ; Nobel et a1 1981) at the SE edge of'the Betic and Sub-Betic orogenic belts of the Alpine nappes over an area of 15 000 km2

(Fig. 15) Ironically, these rocks have historically received more attention than any other lamproite suite, and yet they are the least like the other lamproites under present discussion Niggli (1921) used the MAP suite as a type locality for lamproites 'They were initially described by Lewis (188'7), Yarza (1895), Osann (1889, 1906) and Washington (1903), and more recently by Meseguer Pardo (1924), Jeremine& Faliot (1929), Fallot & Jeremine (1932), Hernandez-Pacheco (1935), Parga Pondal (1915), San Miguel de la Camara (1935, 1916), San Miguel de la Camara et a1 (1952), Fuster & Pedro (1951), Fuster et a!. (1954, 1967), Fuster (1956), Fuster & Gastesi (1964), Hernandez-Pacheco (1965), Marinelli & Mittempergher (1966), Borley (1967), Fermoso (1967a, b), Velde (1969b), Fernandez & Hernan- dez-Pacheco (1972), Pellicer (1973), Caraballo (1975), Lopez Ruiz & Rodriguez Badiola (1980), Nixon et a1 (1982, 1984), Venturelli et a1 (1984a), Hertogen et a1 (1985) and Wagner & Velde (1986a)

Petrographic varieties include jumillite (abun- dant diopside and sanidine with minor phlogo- pite, K-richterite and olivine), f'or.tunite (abundant hypersthene, phlogopite and sanidine with minor olivine, diopside and K-richterite), verite (abundant phlogopite with minor sanidine, diopside and olivine in a glass.rich groundmass) and cancarixite (abundant sanidine and K- richterite with minor olivine, diopside and hyper- sthene) Accessory phases include leucite, Cr- spinel, rutile, apatite, analcime and ilmenite, and alteration phases include quartz, serpentine, carbonate, chloiite and zeolite Wadeite, prider- ite or shcherbakovite have not been reported

Compared with other lamproite suites, the MAP rocks are the most enriched in SiO, and depleted in TiO, and Nb They are also the only lamproites that contain apparently primary mag- matic orthopyroxene It is interesting that the MAP lamproites are least like the other lam-. proites renru rtlicto in terms of' rock and mineral

Lamproites and K

chemistry, despite the fact that Niggli used them as the type locality for lamproites. The jumillites are the most lamproite-like of all the MAP rocks

NWIta ly ( N W I ) (45' 35' N, 7" 45' E ) and Orczat~to Plra, Italy ( P I S ) (44" N, 10" E )

Dykes and rare Bows of post- Alpine ultrapotassic lamprophyre and associated shoshonitic calc. alkaline rocks were intruded N of the Canavese tectonic line in the Sesia-L.anzo and Combin Units (ophiolites, schists) of the internal NW Alps of NW Italy fiom 29 to 33 Ma ago (De Marco 1959; Krummenacher & Evernden 1960; Carraro & Ferrara 1968; Dal Piaz et a1 1973, 1979; Hunziker 1974; Scheusing et a1 1974; Zingg et a1 1976; Venturelli et ai 1984b) The mineralogy of' the NWI ultrapotassic rocks is characterized by an abundance of phlogopite, diopside and sanidine with minor to trace quantities of' altered olivine, riebeckite-arfved- sonite, apatite, sphene, Fe-Ti oxide and carbon- ate minerals (Dal Piaz et a1 1979; Venturelli et a1 1984b) The diopsides and phlogopites from the more ultrapotassic rocks (atomic K 2 0 / N a 2 0 = 5-8) are typical of those of lamproites in that they have low A1,0, contents (less than 0 3 wt % and about 12 wt % respectively). The less- potassic rocks (atomic K 2 0 / N a 2 0 < 3 7), how- ever, contain as much as 1 5 wt % A1203 in diopsides and 15 wt % AI2O3 in phlogopites The geochemistries of the more-potassic rocks are also diagnostically lamproitic, with atomic K 2 0 / AIZO,%O9, atomic K20/Na20%4, high MgO contents (9-14 wt.%) and low CaO contents (4 1- 7 7 wt %) (see Tables 4 and 5) Refractory t race element levels are lamproitic, with 31 5-460 ppm Ni and 600-800 ppm Cr; contents of large-ion lithophile (LIL) elements also display lamproite affinities with less than 850 ppm 21, less than 1240 ppm Sr and less than 570 ppm Rb The NWI ultrapotassic dykes therefore fulfil the lamproite constraints summarized above, al- though Velde and Venturelli (personal commu- nication to Bachinski 1985) group many of these rocks in the minette group

Rocks related to Iamproites (termed selagites) containing olivine, clinopyroxene, phlogopite, sanidine, ilmenite (Borsiet a1 1967), K-richterite, chsomite and apatite were erupted 1-4 Ma ago at Orciatico, Pisa, Italy (Stefanini 1934; Barberi & Innocenti 1967; Wagner & Velde 1986a) H o w ever, these rocks apparently do not contain oligoclase, a phase which Troger (1935) and Johannsen (1911, 1933, 1935, 1939) include in selagites

Pendennu ( P E N ) (50' 5 I?/ 1' 2' W ) and Hoimeade Farm ( H L M ) (TO0 54' N, 3' 28' W ) Cornwall, il K

IJltrapotassic dykes, here considered lamproites, occur on the coast of SW England at Pendennis Point where they intrude Palaeozoic slates (Hall 1974, 1982) Analcime-bearing lamprophyres have been reported further inland at Holmeade Farm near Tiverton (Tidmarsh 1932; Knilll969, 1982; Velde 1971; Cosgrove 1972) Kni11 (1969) likened the HLM rocks to wyomingite and orendites from Leucite Hills and both Cosgrove (1972) and Velde (1971) termed them lamproites despite their minette affinities The PEN dykes are estimated to be Permo-Carboniferous in age (Hall 1982), whereas HLM has been dated at 281 + 11 Ma (Miller & Mohr 1964) 'The HLM locality ialls within the widespread EIxeter vol- canic series which is treated separately below as a suite of non-lamproite ultrapotassic socks

The PEN petrography is characterized by sanidine, phlogopite, alkali amphiboles (riebeck- ite-arfvedsonite), diopside, apatite, barite, spi- nel, rutile, hematite, ilmenite, zircon, quartz, calcite and sulphide The mineral chemistry of the dykes (low A120, in diopside, amphibole and phlogopite) and their extremely ultrapotassic and perpotassic character (Table 4) permits their classification as lamproite Jenru rtricto

The HLM rocks are more difficult to classify with confidence because of a lack of detailed petrographic and mineral chemical data They fall on the margins of the lamproite chemistry range, with atomic K20/A120, = O 6, which is too low for lamproites, and A1,03 = 13 6 wt %, which is too high Their constituent phases include olivine, phlogopite, sanidine, diopside, anatase, magnetite, apatite, perovskite and anal-. cime that was originally identified as leucite (Tidmarsh 1932; Velde 1969b) However, recent work by Jones & Smith (1985) on the L.oxbeare Farm minettes demonstrates that the chemistries ofphlogopites (13-15 wt %A120,), diopsides (2.- 3 wt % A1,0, ; Mg number, 84-87) and sanidines (Or,,-,,; less than 1 0 wt % Fe,03) are more typical of the minerals of minettes than of lamproites

S~r to , Corrrca, France ( C O R ) (42" TO' N 9" 25 'E)

A small Iamproite sill 1.3 5-15 4 Ma old intrudes Mesozoic schists W of the hamlet of Sisco, N of Bastia on the northern past of the island of Corsica (Fig. 16) (P1ime11961; Velde 1967,1968; Feraud et a1 1977; Civetta et a1 1978; Bellon 1981) The lamproite (termedporphyry by Primel,

I34 S C Bergman

ALPINE ROCKS

a MESOZOIC.CENOZOIC OVERLYING HERCYNIAN

ROCKS PALAEOZOIC ROCKS

AFFECTED BY THE

HERCYNIAN

'. Z.J" LAMPROITES 8 SHOSHONITES - FAULTS

. --. - NAPPES

l a )

NEOGENEBSEDIMENTARY ROCKS

EOCENE SEDIMENTARY ROCKS TERTIARY 0 CALC-ALKALIC AND TERTIARY- SEDIMENTARY AND

SHOSHONITIC CRETACEOUS METAMORPHIC ROCKS VOLCANIC ROCKS

% LAMPROITES PERMIANESEDIMENTARY AND

MAW ; ,-' s METAMORPHIC ROCKS *---> ALBORAN SEA

MESOZOIC OOPHIOLITES

-- OBASALTS P A L A E O Z O I C I ~ A C I D VOLCANICS

ROCKS

8'30' 9' 9*30' WGRANITES ,

# LAMPROITE

-FAULT

0 40 km LLJ

n 30 km

Frc 1 5 (a) Map of Spain and NW Africa showing the 16 M~~ of corsica showing the generalized structure and geology and the dist~ibution geology and the location of the sisco lamproite, the of iamproites and other ultrapotassic rocks (Alter size of which has been grossly exaggerated for clarity UNESCO 1971; Venturellietai 1984a; Vila el (11 (After Velde 1967; and Geological Survey of Italy 1974); (b) location map of SE Spain showing the 1961 ) principal Iamproite and other potassic volcanic rock occurrences (after Venturelli el a1 1984a)

Lamproltes and K-rzch lgneous rocks I35

and minette and lamproite by Velde) contains [Bohemian Mass$, C'zethorlovakia (BOH) (49" phenocrysts of phlogopite and altered olivine in N, 1 4 " E j j a groundmass of sanidine, diopside, phlogopite and richterite-arfvedsonite with accessory sphene, anatase, rutile, ilmenite, chromite, psi.. derite and calcite (Wagner & Velde 1985) Phlogopite (13.8-15 wt % A1,03) and richterite (2 3 wt % Al,03; 4 7 wt % K,O) compositions are atypical of lamproites, but the presence of priderite (Velde 1968) suggests lami~roite affini., ties The rock is SiO, rich (56-57 wt Y/,) and MgO poor (6-7 wt %) for lamproites in general but possesses a high K,O content (10%) and high atomic K,O/Na,O and K20/AI,03 atomic ratios (5 4 and 0 9 respectiv~?ly)

[Turcany ('IlJSC) (42O IS' N, 11' 32'EjI

Quaternary volcanic centres at San Venanzo in the Perugia provincs? and at Cuppaello in the Rieti province (both about 50-60 km E of the central volcanic centres of the Latial province) contain kamafugitic lavas (Holm & Munksgaard 1982; Gallo 1984) The geochemistry of the TUSC kamafugitic rocks is very similar to that of the T'oro-Ankole province with the exception of slightly lower TiO,, Nb and Sr contents in the TUSC rocks The relativelv high CaO and low . - ~ ~ - ~ ~~~~ - - SiO, contents and the presence of kalsilite and melilite in the TUSC rocks distinguish them from lamproites.

W Nor way

Two hydrothermally altered peralkaline ultrapo- tassic syenite dykes (Furnes et a1 1982) consist almost entirely of microcline (75%-80%) plus 15%-20% phlogopite, but the presence of the K- ZI silicate dalyite, which is compositionally similar to wadeite, and the Ba-Ti silicate labunt.. sovite, which is similar to shcherbakovite, sug- gests that these rocks have a lamproite affinity As it is not known to what extent the hydrother- mal alteration has modified the primary chemis- try and mineralogy, this occurrence is grouped with the lamproite allies The presence of micro-,

Although most BOH minettes (NEmec 19'72, 197:3, 1974) contain a typical assemblage of sanidine-phlogopite-augite, one particularly mafic and alkali-rich minette dyke also contains alkali amphibole (N&mec 1972) This rock c o n tains 10 8 wt % Al,03, 8 2 wt % K,O and 1 0 wt % Na,O and is geochemically and mineralog-, ically similar to lamproites Schulze et a1 (1985) and NEmec (1985) presented mineral chemistry data on some of the BOH rocks which generally show that these alkaline minettes are distinct from lamproites senru .rtricto However, N6mec's (1985) report of priderite in the BOW socks indicates the need for further study

Holub (1977) described durbachitic plutons (i e syenites) which contain apparently cognate xenoliths of ultrapotassic melasyenites that pas., sess compositions similar to lamproites These xenoliths contain plagioclase and are therefbre not true lamproites Radulescu (1966) discussed ultrapotassic rocks in the E Carpathians

[E,xeter volcanicr (E.XVj (TOo 26' N, .3" 19' W) and Channel irland lamprophyrer (CHNj (49" 13' N,2"8' W), U K 1

The EXV (Hobson 1892; Tidmarsh 1932; Knill 1969, 1982; Tones & Smith 1985) comprise four geochemical groups of rocks (Cosgrove 1972): two are shoshonitic (K,O/Na,O- 1 ; K,O/ A1,03 -0 2) and two are ultrapotassic but are not lamproites (K ,0 /Na20 = 5 and K,0/A1,03 - 0.5) The HL.M lamproite renru latu discussed above falls in Cosgrove's latter group of EXV

The Channel Island dykes form a suite that extends from Guernsey and Jersey to the coast of Normandy,(Lees 1974) and are mainly minettes Wagne~ & Velde (1986a) described minette from St. Helier that is compositionally similar to minettes from NHB They are only mentioned here because of their mildly-ultrapotassic char.. acter and spatial association with the EXV

[Other European Krich rocks] cline is consistent with low-temperature Ie- equ~libration Although these localities are not related to

lamproites, thev are mentioned here because of

[ESrednogorze. Bulgarra (SRE) (42°40'N,260Ej/ the& mildly potassic and alkalic character Potassic volcanics occur in the Roman Province

Potassic rocks of the SRE include leucite basan- (RP) and Aeolian Arc, Italy (Appleton 1972; ites, limburgites, shoshdnitic basalts, trachytes Rosi 1980; Civettaet a1 1981; Barberi et a1 1974, andlatites(eg Boccalettietal 1978) Grozdanov 1978), the Laacher See, F R G (Duda & (1979) and Stefanova & Boyadjieva (1975) dis- Schminke 1978; Wimmenauer 1974), the Hel-, cussed the mineralogy of rocks very close to lenic Arc, Aegean Sea (Innocenti et a/. 1982), lamproites in composition from Svidnya in the Anatolia, Turkey (Keller 1983) and NW Iran Sofia (Riou et a1 1981)

Africa

The most thoroughly studied African lamproites occur at Bobi and Sequela in the Ivory Coast but, in marked contrast with European or American lamproites, only a limited amount of petrological information is available in the literature In this regard, it is ironic that Africa is the site of the largest number of petrogenetically related kim-, berlites for which a wealth of data is available The kamafugitic ultrapotassic province at Toro- Ankole on the E African rift is not a lamproite suite but is perhaps the most thoroughly studied suite of its type The Ibllowing larnproite s u m maries must therefbre be disappointingly brief until more thorough studies are published

Bobz-Sequeia, Ivory Coast (BOB) (8" 9' N, 6" ??' W )

Sheared dykes, termed 'meta-kimberlites' by Bardet (1973), intrude Archaean crystalline rocks in the Bobi and 'Ioubabouko regions, Seguela, central Ivory Coast (Knopi' 1970; Bardet 1971; Mitchell 1985) These dykes are thought to be 1150-1430 Ma old and diamondiferous in char- acter (Bardet & Vachette 1966; Bardet 1973) The BOB dykes possess a geochemical signature similar to that of lamproites (Table 4); however, it is not known to what extent metamorphism has modified theirprimary composition Dykescalled fitzroyite and wyomingite by Bardet (1973) occur in the BOB area; they lack pyrope and ilmenite but contain abundant chromite Intimately asso- ciated Proterozoic kimberlites and alnoites fol- lowed the strike of older fracture systems during their emplacement The mineralogy of the BOB 'meta-kimberlite' includes phlogopite, diopside, spinel and talc Alluvial diamonds from the Seguela area have been traced upstream to dykes of altered fitzroyite and mica-peridotite (Dawson 1967a, b ; Knopf 1970)

Luanglva Graben, Zambza ( L UA) (11' S, 33'E)

Little has been published on the K-~i-richterite- bearing lamproites from the Luangwa Graben (Murray, personal communication to Dawson 1970; Dawson 1980, p 8 ; Mitchell 1985) A recent review of diamonds (Wilson 1982) men- tions the probability of their existence Kimber- lites in the area have been briefly discussed by Dawson (1970, 1980)

The l'ampr oites include dykes, pipes and craters which intrude Karoo sedimentary rocks and are probably Ju~assic to Cretaceous in age (B Scott- Smith, personal communication, 1986) Crater

facies lapilli tuff's and associated pyroclastic and epiclastic deposits occur in the LUA All of the characteristic lamproite phases occur (B Scott-, Smith, personal communication, 1986), yet wad.. eite or priderite have not been discovered The LUA is an exceptional lamproite that occurs in a well~developed continental rift setting

Pnzel, Postmarbu~g, Srvartruggens etc South Afizca (PPS) (33" 54 'S , 18" 58' E )

Dykes of phlogopite-rich and leucite-bearing 'lamprophyres' are found in association with diamondiferous micaceous kimberlites at the IIellam Mine at Swartruggens, S Africa (Skinner & Scott 1979; Hargraves & Onstott 1980) The Swartruggens 'leucite lamprophyie' contains phlogopite, olivine, diopside, leucite and spinel (Skinner &Scott 1979) and possesses a geochem-. ical composition closer to that of' olivine lam- proites than that of leucite lamproites (Table 4) Lamproite dykes are also reputed to occur at Pniel (Baster's Mine), Postmasburg and Pielans- burg in the Johannesburg and Kimberley areas of S Africa (Dawson 1970, 1980, p 8 ; Erlank 1973; L G Krol, R Mitchell and A J A Janse, personal communication, 1982, 1985) Feldspa- thoid-bearing kimberlites (typically containing nepheline, often out of Sr istopic equilibrium with the host rock (Smith 1983b)) have been reported by De Beers (Skinner, personal com- munication to Smith 1983b) at Klipfontein (28' 23' S, 24" 08' E.) and Poortjie (28' 01' S, 24' 17' E) Unfortunately little information is currently published on their geochemistry and mineralogy The compositionally related (perhaps identical?) Gioup I1 kimberlites of S Africa are discussed by Smith (1983b) and Dawson (1987)

[Taro-Ankole and Bzlunga volcanzc field 1Jganda ( T A N ) ( I 0 S , 29' E ) ]

Potassic-ultrapotassic mafic-ultramafic rocks at 'Ioro-Ankole and Birunga characterize the west- ern branch of the E African rift valley system in SW Uganda 'Tuff's, lavas, agglomerates and explosion breccias consist of a variety of kama- fugitic rock types, ranging from melilite.. and kalsilite.bearing katungites through olivine leu- citites to K-trachyandesites (Holmes 1950; Bell & Powell 1969; Edgar & Arima 1981; Ferguson & Cundari 1982) The more mafic rock types do not contain any plagioclase or K-feldspar These rocks are not larnproites renru stricfo, despite the fact that some workers (e g Vollmer & Norry 1983b) refer to them as such 'The TAN rocks are

Lamproltes and K-rzch zgneous rocks I37

by their nepheline, melilite and kalsilite, as well as by their elevated A1,0, and CaO contents and lower SiO, contents (Table 4)

[Azzaba, Algeria (AZZ) (36'41' N 7" 5 E)]

Glassy dykes and extrusive rocks, termed 'potas- sic olivine trachytes' by Vila et a1 (1974), occur near Azzaba, Algeria (see Fig 15a). Olivine ranges in composition from Fo,, to Fo,, and occurs with augiie, sanidine and chromite (Vila et a1 1974; Velde, personal communication, 1985) The AZZ rocks are ultrapotassic (K20/ Na,O= 3 5), but their A1,0, contents are rather high for lamproites (12 9%) and the rocks are peraluminous with atomic K20/,4I20, = 0 6 'These rocks are therefore best described as lam~roites renru lato until more detailed mineral chemistry and petrogxaphic data are available

[Shakr and Okeho SFVNigeria (SHO) (8' 39' N, 3" 25' E ) ]

Ultrapotassic, nearly perpotassic syenites and biotite pyroxenites occur in several isolated bodies in the basement complex of W Nigeria (Oyawoye 1976) They consist of' microcline, albite, biotite, amphibole, pyroxene, quartz and sphene, and possess atomic K20/A120, ratios of 0 6 and atomic K,O/Na,O ratios of 3 with 8 7 wt % K 2 0

Antarctica

Figure 17 shows the location of the three known lamproite senru rtrictooccurrences in Antarctica:

ARCHAEAN GRANITES, ICE

- FAULT 4 LAMPROITE

FRACTllRE ZONES

--- MAGNETIC ANOMALIES

+ SEAMOUNT

Gaussberg, Mount Bayliss and Priestly Peak These rocks range in age from Palaeozoic to Quaternary and the most recent rocks at Gauss- berg occur on the E coast where an extension of the Kerguelen Plateau of the Indian Ocean intersects the continent The 2000 km long Ker- guelen-Gaussberg aseismic ridge has been the site of extensive hot-spot activity, involving the generation of mildly.-potassic alkali basalts, for the last 27 Ma (Stephenson 1972; Nougier 1970)

All the Antarctic lamproites are rich in TiO, (3-5 5 wt % TiO,; average lamproite, 2 8 wt.%) and LIL elements (400-1500 ppm Ba, 900--1800 ppm Zr, 1300-,3000 ppm Sr, 40-1 50 ppm Nb and 270-350 pprn Ce) The Antarctic lamproites are also particularly rich in P20 , with 1 5- 3 3 wt % (4-10 modal %apatite); they share this trait with the Indian apatite-rich lamproites (see below). It should be noted that E India and E Antarctica were adjacent prior to the breaking of Gondwan- aland, which suggests a unique character in the underlying mantle lithosphere

Gaurrberg (GSB) (66' 48'S, 8Y0 19' E )

Lencite lamproite lavas and tephra were er.upted fiom the C?aussberg volcano approximately 56 000 years ago on the coast of Wilhelm I1 land, E Antarctica (Drygalski 1904; Phillipi 1912; Reinisch 1912; Lacroix 1926; Nockolds 1940; Vyalov & Sobolev 1959; Sheraton & Cundari 1980; Cundari & Ferguson 1982; Tingey er a1 1983) The more recent K-Ar work on leucite separates by 'Tingey et a1 supersedes the whole.

Frc 17. Gene~alized geology of E Antarctica and the southein Indian Ocean showing the distribution of lamproites and seamounts of the Kerguelen-Heard Island chain (After IJNESCO 1976; Sheraton & England 1980 )

138 S C Bergman

rock K-Ar work of Ravich & Krylov (1964) and Soloviev (1972) which suggested ages of 20 Ma and 9 Ma respectively In addition, Sheraton & Cundari (1980) and Tingey et a1 (198 3 ) described as fission-track work by Gleadow which sug- gested an age of 25 000+ 12 000 years Dort (1972) postulated a late Pleistocene to Recent age on the basis of geomorphology 'The GSB lavas have been termed leucitites by most workers The lavas are nearly aphyric with phenocrysts of olivine, diopside and leucite in a nlassv matrix (50%-60% o? the rock) containing q&nchcrystals of leucite, diopside, phlogopite, amphibole, il- menite and chromite (Sheraton & Cundari 1980) (Fig 4) The mineral chemistry of the silicate phases is diagnostic of lamproites withlow Al,O, contents in diopside and phlogopite (averaging 0 4 wt % and 6 9 w t % respectively) The GSB whole-rock geochemistry is also typical of lam. proites ('Table 4), and emphasizes its perpotassic and ultrapotassic character Both cognate (oli-. vine-diopside-leucite-phlogopite) and acciden- tal (spinel Iherzolite) xenoliths occur in the volcanics (Sheraton & Cundari 1980) Collerson & McCulloch (1982) discussed the Nd and Sr isotope and rare-earth element geochemistry of the GSB lavas

Mount Baylis, (MBAY) (73" 26' S. 62" 50' E )

A dyke 5 m thick, termed 'melasyenite' by Sheraton & England (1980), intruded Archaean felsic rocks during the Silurian (411-430 Ma) in the southern Prince Charles Mountains, Mac. Robertson Land, approximately 300 km SSW of the Radok Lake alnoites (Trail 1963; Walker & Mond 1971; Sheraton & England 1980; Tingey 198 1 ; Sheraton 1983). Mediumgrained rocks are composed of microcline, K-sichterite, K-arfved- sonite, phlogopite, apatite, anatase, zircon, cal- cite and Fe-Ti oxide Finer-grained samples have been recovered from MBAY and these differ slightly from the coarser-grained rocks in that they contain pseudoleucite, more phlogopite, less amphibole and ilmenite The mineral chemistries of'MBAY phlogopitesand amphibolesaresimilar to those from WKB and LH lamproites The geochemistries of the MBAY rocks are also typical of larnproites in that they possess atomic ratios K 2 0 / N a , 0 = 3 2 and K2O/Al20, = 1 1 ; however, they are more evolved than the average lamproite (Mg number, '74) with an Mg number of 56

Priestly Peak (PP) (67" ll' S, 50" 2 2 E j

A sim~lar dyke (albeit undated) cuts a Proterozoic dolerite dyke at Priestly Peak in Enderbyland

near the coast (Sheraton & England 1980; Sheraton etni 1980) ThePPdykeisfines grained than that of MBAY and consists predominantly of phlogopite, microcline and K-'arfvedsonite with minor arnounts of apatite, quartz, rutile, sphene, zircon and barite (Fig 4) The PP dyke (Mg number, 70) is similar in composition to the GSB lavas (Mg number, 70) in that it is more primitive than the MBAY dyke (Mg number, 56)

Asia and Indonesia

The only known occurrences of lamproite sensu rtricto in Asia and Indonesia are the Indian dykes at Chelima and the Gondwana Coalfields Those at Coc Pia, North Vietnam are closely allied to lamproites Phlogopite-leucite 'basalts' occur in central Kalimantan; however, the petrological data required to characterize them are not available Potassic-ultrapotassic intrusive and extrusive rock suites have been reported for several areas in the U S S R In recent discussions with geologists at several Chinese geological institutes it was found that lamproites have not yet been recognized in China (C Hearn & A J A Tanse, personal communication, 1985)

Coc Pia and Sin-Cao, Upper Tonkm N Vietnam (COCj (22" IS' N 103" 30'Ej

These larnproites, termed 'cocites' by Lacroix (1926,1933a, b), occur near the N Vietnam-Laos border in Indochina The dykes at Coc Pia cut Mesozoic alkaline syenites and granites and are grey fine-grained rocks consisting of olivine, diopside, phlogopite, magnetite, sanidine and leucite (Lacroix 1933a) According to Fromaget (1933), alkaline dykes also occiir at Sin Cao, HE of Laid Chau, where they intrude Triassic sediments The Sin Cao rocks consist primarily of augite and phlogopite phenocrysts with sani- dine and analcime pseudomolphs after leucite in the groundmass. Lacroix (1913a) included the Sin Cao rocks in his cocite group, and noted their chemical and mineralogical similarity to the Spanish jumillites

The geochemistry of the COC rocks is typical of lamproites with the exception of a sather low K 2 0 value (4%-5%) and low atomic K,O/Na,O and K20/A120, ratios (about 1 0 and 0 4-0 6 respectively) However, these discrepancies can be easily reconciled if' the possibility of late- to post.magmatic alteration of leucite to analcimc is considered

Lacroix (1933a) and Fromaget (1933) also described shonkinites and nephelirle syenites at Pin Chai, S of Pu To and N of Lai Chau in Upper

L,amproztes and A

Tonkin Wagner & Velde (1986b) re-.examined the two type specimens from Coc Pia and have noted the absence of Ti-rich oxides and K- richterite, and the presence of the Ti-rich phlo- gopites titanomagnetite and feldspars (Or,,_,,) These two type specimens fulfil the mineralogrcal and compositional requirements for inclusion in the lamproite renru rtrrcto group; however, feldspar compositions are different from those of true lamproites Further field work is thereibre justified to search for other potential lamproites in the Coc Pia area

Chelimn ( C H E ) ( 1 jC 27' N, 78O 4 1 15) and Gondwana Coaifieldr (GDW) (24" iV. 86'E), Indza

Proterozoic (1200 (Ma old) (Crawford 1969; Crawford & Compston 1973) phlogopite-rich, mafic--ultramafic dykes intrude Proterozoic shales of the Cumbum formation over a 10 km x 6 km area near the Chelima Railway Station on the western margin of the Cuddapah Basin and the eastern margin of the Dharwar craton, A n d h ~ a Pradesh, India(F ig 18) (Appavadhanulu 1962; Sen & Narasimha Rao 1970; Sarma 1983; Bergman & Baker 1984) The two early reports described the dykes as minettes and the rocks as transitional between kimberlites and carbona- tites, but the last work suggested, on the basis of rock and mineral chemistry, that they are larnproites The rocks occur with massive mag- matic to glassy breccia phases and consist of abundant foliated phlogopite (with talc and chlorite secondary intergrowths), rutile, apatite, perovskite, ilmenite, serpentine pseudomorphs after olivine and a secondary ferroan dolomite Phlogopite composition and zoning characteris-. tics are typical of larnproites (see below and compare Mitchell (1985)) with (cote -. rim): Mg number, 85 -* 65; Al,OJ, 11 - 8 wt %; TiO,, 5 5- 3 5 wt.%; BaO, 0 7 - 0 3 wt%; Cr,O,, 0.2 -+ 0.0 wt % The geochemistry of'the dykes is also typical of lamproites when corrected for the dolomite alteration (compare with Table 4): 48 wt % SiO,; 5.0 wt % AI20,; 7 4 wt % TiO,; 9 4 wt % FeO; 18 9 wt % MgO; 4 2 w t % CaO; 0.2 wt % Na,O; 3 3 wt % K,O; 2 5 wt % P,O,; 560 ppm Cr; 450 ppm Ni; 2500 ppm Ba; 1920 ppm Sr ; 160 ppm Rb; 380 ppm L.a; 700 ppm Ce; 1020 pprn 21 Sen & Narasimha Rao (1970) noted micro-diamonds in the Chelima dykes; ancient workings, presumably for diamonds, are also present Alluvial diamonds occur in an adjacent drainage within 6 km of this area (Bergman & Baker, submitted for publication)

A widespread suite of Mesozoic lamprophyres and mica peridotites, some of which contain

-rzch lgneous rocks I39

leucite, occur about 1000 km to the NNE of the CHE dykes in the Gondwana Coalfields at Jharia, Bakaro and Raniganj on the N margin of the Singhbum craton (Fox 1930; Chose 1949; Baner-, jee 195.3; Makherjee I961 ; Sanyal 1964; Chatter-, jee 1974; Sathe & Oka 1975; Sarkar et a1 1980) The geochemistry of the leucitebearing GDW dykes is typical of lamproites (Table 4) and is much more mafic than typical minettes (compare with Rock 1986) Chpta et a1 (1983) discussed the petrology of carbonated apatite glimmerites from the Damodar Valley which contain phlogo- pite, apatite, ankerite and chrome spinel pheno- crysts in a groundmass ofthe same minerals plus [utile, devitrified glass, priderite and pyrite All these GDW dyke rocks are extremely enriched in P,O, (3--6 wt %), TiO, (5-7 wt %) and carbonate minerals (10--20 wt % C 0 2 ) compared with typical Iamproites and, as a group, probably represent a distinct subtype of the lamproite clan

Indian kimberlite diatremes (840-1200 Ma old) are known in three districts: at Wajrakarur (more than six pipes), in the core of the Dharwar craton (about 250 km W of the Chelima dykes), and at Panna (more than four pipes) and Jungel (more than three pipes) near the SE margin of the Aravalli craton (500-800 km W of the Gondwana Coalfield dykes) (Satyanarayana Rao & Phatare 1966; Crawfosd & Compston 1970, 1973; Marthur & Singh 1971; Paul et a1 1975; Balasubrahmanyan et a1 1978; Paul 1979; Murty 1980; Murty et a1 1980) Alluvial diamonds are widespread throughout central and northern India. Although the larnproites discussed above are widely separated from these three kimberlite occurrences alluvial diamonds and lamproites do occur in the same areas Further work is clearly required on the Indian lamproites and lampro- phyres

Kajan River, Kalirnantan (KA1) ( l o 30'N, 11 To 30' E )

Brouwer (1909) reported a phlogopite-leucite basalt on the Kajan River, central-E Kaliman- tan, containing resorbed phenocrysts of phlogo- pite with reverse pleochroism, typical of the tetraferriphlogopites from lamproites and kim- berlites (Mitchell 1985); additional minerals include leucite, diopside, olivine and Fe-Ti oxides The KAJ geochemistry, however, is not strictly lamproitic (K2C3/AI20,=O4; K 2 0 / Na10=2 O), and until more detailed data are available the KAJ rock must be grouped outside the lamproite clan L.acroix (1926) included the <kajanite' in his systematic treatment of the syenitic leucitites, but Niggli (1923) was appar- ently unaware of the kajanite occurrence or

Q U A T E R N A R Y U SEDIMENTARY ROCKS

TERTIARY- SEDIMENTARY PAL.AEOZOIC ROCKS

DECCAN SASALTS

PROTEROZOIC @ A R C H A E A N

HIMALAYAN @ OROGEN

(PROTEROZOIC TO TERTIARY)

t LAMPROITE LAMPROPHYRE

0 KlMSERLlTE V ALLUVIAL DIAMOND PROVINCE

FIG 18. (a) Generalized geological map of India showing the three Archaean cratons and the distribution of lamproites, kimberlites, lamprophyres and diamonds (after Roy 1962; Roy Chaudhury 1973); (b) geological map of' Andhra Pradesh State, India, illustrating the location of the Chelima lamproite, Wajrakrur kimberlite and alluvial diamond occurrences (after Roy 1962; Roy Chaudhury 197.3); (c) map showing the distribution of lamproite dikes at Chelima, Andhra Pradesh (after Sarma 1983)

neglectedit in his t~eatiseonlamproites Be~gman et a1 (1985) discussed the mineral and rock chemistry of minettes of non-lamproite affinity in the nearby Karamu River area, central Kaliman- tan. Bucking (1899) noted a biotite.leucite basalt in the S Celebes

Indonerzanarc uolcan~cr ( I A V ) 16" S I l l o E )

L.eucite basalts, tephrites and potassic andesites characterize isolated occurrences from the active Sunda arc in Java, the Celebes and other islands, and are peraluminous with low atomic K,O/ AI,O, ratios (0 2-0 3) and elevated A1,0, con- tents (16-22 wt %) (Grubb 1965; Baren 1948; Foden 198:3)

Bazkai-Aldan Belt ( B A L ) and Pamn, Mongolza (PAM) , U S S R

Potassic-ultr.apotassic rocks are widespread along the 1500 km Baikal-Aldan alkalic intrusive belt on the Siberian Platforni (Mineyeva 1972;

Maksimov 1982; Kostyuk 1983) The most ultrapotassic occurrences (those of the Synnyr, Murun and Inagli massifs) do not, apparently, include lamproites 'They are petrographically and geochemically similar to the HM, SEW and BRA ultrapotassic suites

Lacroix (1926) made an obscure mention of several 'kajanites' (phlogopite-leucite-diopside- olivine basalts) from Vouyerska Kosa and Sveta Petka, Siberia (with a reference to Raoult and a personal communication from M Koyitch)

South America

Braz~l ( B R A ) (20°S# 48' W )

Shoshonitic volcanics, shonkinite and kamafw gitic rocks occur in isolated localities in Brazil (Ulbrich & Gomes 1981, and references cited therein) Associated rock types include ugandite, analcite basalts, 1inibur.gite and minette, and

Lamprortes and K-r~ch zgneous rocks

QUATERNARY UALLUVIUM N E O G E N E ~ S A N D S T O N E TERTIARY 0 DECCAN TRAPS MESOZOICO SEDIMENTARY

ROCKS

u PROTEROZO~C@KURNOOL SG B A L K A L I N E ROCKS DCUDDAPAH SG OCLOSPET GRANITE

L PROTEROZOIC~DHARWAR SG A R C H A E A N ~ C H A R N O C K I T E S

METAMORPHIC ROCKS

+ LAMPROITE KlMBERLlTE

T ALLUVIAL DIAMOND OCCllRRENCE

- LAMPROITE DYKE

- ROAD . - . -. . . RAILROAD

although kimberlites and other alkalinerocks are widespread in Brazil (Svisero et nl 19'79a, b, 1984), lamproites senru rtrlcto have not yet been reported

Age of emplacement

Known lamproites range in age from Proterozoic (Argyle, Holsteinsborg and Chelima) to Quater- nary (Leucite Hills and Gaussbesg) Of the 21 lamproite suites or localities recognized here,

nine are Cenozoic, four are Mesozoic, four are Palaeozoic and four are Proterozoic Therefore, in addition to xenolith-bearing alkali basalts, lamproites are apparently most common in the Cenozoic 'This age relationship could result from selective preservation of the extrusive members of recent suites or alternatively from some mantle or tectonic process permitting their formation which has been most active in recent times The fact that the intrusion of Indian-Antarctic- Australian lamproites (CHE, GDW, GSB,

MBAY, PP, ARG and WKB) has taken place in the same large region (when corrected for continental drift) over more than a billion years suggests thBt the former hypothesis may be the most likely explanation

On the basis of the better-studied Cenozoic suites (e g WKB and MAP), intrusive-extrusive activity takes place over a time span of 2-10 Ma In areas such as the Fitzroy Basin the emplace- ment of primitive diamondiferous olivine lam- proite diatremes can occur contemporaneously with that of more differentiated leucite lamproite flows and plugs (Jaques et a1 1984a) Therefore it is possible that diamondiferous olivine lam- proite diatremes may be erupted in the Leucite Hills area in the next 10 Ma! However, the WKB suite is the only one in which such contemporan- eity has been noted

Intr usive-Extr usive forms

Lamproites have been reported to occur in nearly every igneous form possible, the most common being dykes and flows The most recent lam. proites from GSB and L.H display all the volcanological features typical of alkali basaltic eruptives, with classic lava flows, pyroclastic ejecta, cinder cones etc (Fig 19(c)) Therefore there is sufficient evidence to suggest that the more eroded slightly older lamproites (e g WKB) that occur as dykes and necks also probably possessed extrusives similar to those present at L.H and GSB Lamproite sills occur at HP and COR, and a shallow coarse-grained (grain size of less than 2 cm) lamproite pluton occurs at the 2 km diameter Wolgidee Hills intrusive (WKB) Vesicular rocks are ubiquitous in all but the hypabyssal intrusives; extremely vesicular scori., aceous lavas occur at GSB, LH and MAP among others Palagonite and agglutinate tuff's (welded fall-out tuffsequivalent toplperno) and/or bedded pyroclastics occur in the more recent suites (e g GSB, LH, MAP, SB, WKB and PRA) 'Their absence in older suites can be easily attributed to selective erosion of extrusive forms These extru- sive facies are evidence of base surge as well as other volcanic processes (Atkinson et a1 1984b), Autolithic breccias composed of fragments of magmatic lamproite that are often plastically deformed and set in a fine-grained groundmass consisting of both magmatic and xenolithic (pulverized country rock) material characterize the contact zones of nearly every lamproite intrusive (Figs 3 and 4) These autolithic breccias are diagnostic of' lamproites and are texturally similar to pyroclastic breccias associated with silicic volcanic centres Glass-rich rocks are

present in many lamproite sensu rtricto occur., sences (e g LH, GSB, MAP, WKB and SB)

The size of lamproite occurrences varies widely from locality to locality, from dykes of limited aerial extent less than 1-2 m wide at HOL, NWI and MBAY, PP and CHE, through small plugs (10-100 m wide) at KAM, MAP and HP, to the volcanic cone '370 m high and 1400 m indiameter at GSB The estimated total volume of the erupted material at LH, WKB and MAP exceeds 10-100 km3 in each case Therefore, whereas lamproites are volumetrically of limited size compared with mafic alkalic igneous rocks in general (Mauna Loa volcano, Hawaii, alone exceeds 100 km3), a given eruptive suite can approach the size of' a continental alkali basalt volcanic field

Lamproites also occur as diatremes or pipes, and these igneous forms have the greatest

A R ? ~ ~ h k s e lamproite diatremes differ in ap- pearance from the typical kimberlite diatremes (Figs 19(a) and 19(b)) Whereas kimberlite pipes tend to be carrot-shaped and possess 2--3 km of ve~tical flaring (Hawthorne 1975; Harris 1984), Iamproite diatremes are characterized by afunnel or sherbet-.glass shape with less than 0 1-0 5 km of vertical flaring This contrast has important diamond-exploration implications (i e volume calculations and magnetic modelling) and can be reconciled by a consideration of the volatile abundances and compositions of the respective intrusive systems (Harris 1984) The larger proportions of both CO, and H,O (a factor of 2.- 3) in kimberiites relative to lamproites produces a relatively-deep (2-3 km) explosive boiling stage in the former intrusives The volatile budgets of iamproite magmas are dominated by the ex- tremely-soluble H,O so that they boil at shallower depths of less than i km An alternative expla nation for the difference in shape between kimberlite and lamproite diatremes involves the relatively-shallower erosion level displayed by the latter Since the vast majority of kimberlites are Pre-Cenozoic, whereas most lamproites are Cenozoic, this erosion level can be easily ration- alized However, even the older (Palaeozoic) lamproites (e g Argyle) display tuffaceous facies

Tectonic--geological environment

Whereas some of the lamproite renru lato or compositionally related shoshonite localities oc- cur on the margins of continents or in oceanic margins (e g Indonesia and the Mediterranean), the 21 lamproite renru strzcto localities described above all occur in continental regions This

Lamproztes and K-rzch lgneou5 rocks

KIMBERLITE DIATREME MODEL. - --7-- . /

FIG 19 Idealized cross-sections showing the morphological features of (a) olivine lamproite diatremes, (b) kimberlite diatremes and (c) alkali basalt cinder coiies (After Hawthorne 1975 )

continental feature is shated by alkalic rocks in general (Bailey 19'74) as well as by leucite-bearing rocks, with the exception of the four oceanic islands discussed by Gupta & Yagi (1980): the Cape Verde Islands, the Kerguelen Islands, the Marquesas Islands and Tristan da Cunha How- ever, whereas alkaline basaltic magmas with N a > K (weight basis) characterize nearly all well-developed continental rift systems (Bailey 1974; Barberi et a1 1982), with the exception of LllA, lamproites sensu strict0 are absent and only

LAMPROITE PIPE MODEL A

ALKALI BASALT CINDER CONE AND FLOW MODEL ( b )

a few related ultrapotassic rock suites (e g LAC, TAN and BAL) occur in well-developed conti- nental rift systems

L.amproites are, in general, the result of post- o~ogenic magmatic phenomena in regions that have experienced collisional orogenesis (with underlying fossil Benioff zones) several tens to many hundred million years prior to their eruption In contrast, shoshonitic rocks are characteristically more directly linked with sub- duction Morrison (1980) found that, while

I44 S C B

shonkinites are associated with calc-alkaline rocks of orogenic zones, they tend to be younger and occur over the dzeper parts of Benioff zones or in association with block faulting and uplift accompanying the 'flipping' of a subductionzone Therefore, whereas shoshonites are temporally associated with the waning stages of subduction, lamproitesare clearly post-subductionand appar- ently require the passage of time in addition to the stabilization of orogenic belts for their formation It should be noted that Helmstaedt & Gurney (1984) related the kimberlites of S Africa to subduction processes

In contrast with the general restriction of kimberlites to ciaton interiors (e g Janse 1984; Dawson 1980), lamproites generally occur closer to craton margins In contrast with ocean island chains which young in a certain direction, lamproites do not and they consequently do not owe their presence to hot spots Note, however, that Edgar (1983) related ultrapotassic magma- tismof the Westernu S A (includinglamproites) to the Yellowstone mantle plume

Several lamproite suites are associated with broad anticlinal or synclinal structures (e g WKB, LH and KAM), whereas others intrude relatively undeformed sedimentary-platform sed- iments resting on Proterozoic basement rocks marginal to the core of the continental craton (e g HP, PRA, SB, WKB and LH) Nearly all lamproite suites are associated with surficial lineaments or fault lines which probably connect with well-established deep basement fractures or zones of' weakness Lamproites share this feature with kimberlites and many other mantle-derived extrusive and intrusive rocks

Rowell & Edgar (1983), speculating on the spatial relationships between 15 dated occur. rences of Cenozoic K-rich volcanics (K,O> Na,O; SiOz.:60 wt %) in the western U S A and the outer limits of palaeo-arc-related mag- matism, suggested that the K..rich volcanism was directly related to deep subduction rather than intra-plate tectonics Although most of the non- lamproite potassic suites correlated well, none of the lamproites renru rtricto did: they were emplaced long after the ambient western CJ S A subduction had ceased Lamproites are therefore controlled by intra-plate tectonic processes, al- though an association with regions that have experienced collisional orogenesis is indicated by the more recent suites

Diamondiferous character

Except for the CHE. lamproite in India which requires more study, there are five known diamondiferous lamproite suites: WKB, ARG,

'ergrnan

PRA, LUA and BOB As the first three have received detailed study, but the latter two have not, the following is based largely on the first three suites Diamondiferous lamproites all share the following features 1 They are generally olivine lamproites (mafic to ultramafic) with elevated refractory element contents: 14-30 wt % MgO, 35-56 wt % SiO,, 2- 6 wt % CaO, 0 1-0 8 wt % Na,O, 3-7 wt % A120,, 400.- 1300 ppm Ni and 300- 1800 ppm Cr (Tables 5 and 6) 2 'They are moderately toextremely enriched in incompatible elements: 1-6 wt % K,O, 100-500 ppm L.a, 100-600 ppm Ce, 200-1 1 000 ppm Ba, 100-600 ppm Nb, 100-700 ppm Rb, 100-2000 ppm Sr and 200-1200 ppm 21; many of these concentrations are in excess of those found in kimberlites 3 They occur as diaGemes with sherbet-glass or funnel-shaped cross-sections, are relatively large in surface area (75-210 acres) and possess multiple intrusive--extrusive phases including a massive magmatic phase, breccias and tuffs 4 They can occur throughout geological history, with the five diamondiferous magmas discovered heretofore erupting in Precambrian, Cretaceous and Miocene times 5 They are distinctly different from non-dia- mondiferous varieties of lamproites The average major- and trace-element compositions of dia- mondiferous lamproites are compared with those of barren lamproites below (see Tables 5 and 6)

Although abundant associated leucite lam- proite intrusions are only found in the WKB suite, further mapping is likely to reveal associ- ated differentiated lamproites in the PRA and ARG suites The eruption of diamondifero!ls olivine lamproites in the WKB suite is contem- poraneous with that of more differentiated leucite lamproites

Lamprophyre versus lamproite

Although the term 'minette' in its present sense, has been used for over 150 years (Bachinski, personal communication, 1984), Gumbe1 (1874) introduced the broad textural term 'lamprophyre' or 'shining rock' in reference to a dark dyke rock composed of mafic phenocrysts and groundmass phases Rosenbusch (1887) gave the term its present significance by defining 'lamprophyres' asdark-coloureddykerocksofporphyritic texture characterized by a panidiomorphic texture and consisting o f ' a high percentage of mafic minerals as phenocrysts in a fine-grained groundmass composed of the same mafic minerals as well as feldspars and/or feldspathoids Streckeisen (1980) emphasized the feature that feldspars and/

TABLE 6. Summarj) 0,fauerage iamprorte surfe trace-elemerlf geochen~~sfry compared wlth alkalr bnsalts, kmlberlrtes, other K-rrch alkalnte rocks, nml t/?e prlmltlve mantle

Mean rrace-elemenr content (ppm)

11' Lz Ce Nd Srn Eu Gd Tb Dv Yb Lu v U Th Rb Sr Ba Zr Cs Ta Hf Nb Ni Cr Co V Sc

Slirrest ARC I 150 10 600 800 400 I00 400 600 40 CllE 2 322 600 239 36 7.3 2 I . 2.5 0.33 40 3.8 27 135 1635 2120 865 14 15 380 475 49 115 31 GDW 5 629 1060 501 90 46 123 4230 4860 i i 60 340 245 58 28 GSB <4 230 420 150 19 4 5 9 8 0 45 18 2 5 30 300 1830 5550 1000 qn 77n 71n I ~n

~ ~ ~ ~~~~ . ~ . . - - - . - -, MAP 15-21 105 284 169 31 5.1 15.7 7.2 2.08 0.29 16 23 249 930 3460 730 65 415 770 31 102 18 2 MR AY 6 159 286 34 5.8 20 233 2310 8370 i580 77 220 271 143 NIVI 4-5 164 273 I79 5.: 2.2 IS9 50 33 I56 430 820 600 1.9 15.1 40 386 700 107

? 0 -

PEN 1 274 616 264 32 6 5 18 0 8: 2 1 0 3 0 36 2350 6310 1890 41 177 7hl 77 17x I-

(CSN) 4 40 76 39 7.4 1.7 4.0 1.1 1.38 0.20 49 1.2 3.4 219 2110 4290 576 2.6 1.0 13.8 226 480 34 l 7 9 (HMI

Y 53 98 43 8.2 2.2 0.S 3.9 1.72 0.25 16 2.2 11 174 1290 4460 147 2.7 0.6 5.8 23 148 365 39 18 r;

(NSW) 34 137 1510 2020 606 342 365 40 27 3- (SUNN) 2 90 144 88 15 I52 1390 960 66 91 102 21 183 (TUSC) 9 334 40 81 418 2790 2170 500 29 104 445 37 100 19

3~ (TAN1 7 135 280 17 3.4 1.2 0.72 0.09 30 18 220 6600 3300 750 12 6.4 169 180 720 70 270 23 2

E L2

Rocti rype niierngei Y

Lamnro~les 30-180 240 400 207 24 4.8 13 1.4 6.3 1.7 0.23 27 4.9 46 272 1530 5120 922 1.7 4.7 39 95 420 580 37 123 17 2 Barren lamproltes 40-150 230 390 220 25 4.9 13.6 1.4 6.4 1.7 0.24 29 5.5 48 270 1600 4800 950 1.8 2.2 41 82 360 520 33 130 17 Diatnondiferous lamorolres 13-20 275 445 165 21 4.5 9.8 1.4 6.1 1.6 0.21 18 3.5 37 305 1200 7550 730 1.1 8 30 170 810 1010 60 100 19 Kimberlltes 10-100 150 200 85 13 3.0 8.0 1.0 1.2 0.16 22 1.1 16 65 740 1000 250 2.2 9 7 110 I050 1100 77 120 I5 Alkali basans 10-100 54 I05 49 9.1 2.5 8.i 1.8 4.7 1.9 0.5 33 0.7 3 32 530 528 189 19 5 69 145 202 43 213 20 Alkaline & calc-alkaline l a r n p r o ~ h ~ r e s 50-200 105 195 100 22 4.9 14.3 1.8 5.7 1.9 0.37 36 5.0 24 115 1010 1345 350 5. i 9 83 I553 40 37 200 21 Ultramafic larnprophyres <48 136 230 110 19 4.7 10.9 I.? 6.9 2.8 0.28 60 8 22 70 I340 1400 330 ? 7 6 120 435 540 57 I80 25 L'rbrniove mantle - 0.50 !.: 0.97 0.31 0.12 0.42 0.08 0.52 0.34 0.052 3.0 0.018 0.07 0.5 16 5 8 0.02 0 2 0.23 0.6 2000 3000 100 84 11

P : Sutle abbrev~atrons from texr and Tables 2 and 3 1 sources listed in Appendix 1. cn * Vanable numbersoisamoles reflect var~able elernelirs gtven in different sources.

146 S C E

or feldspathoids, when present, occur only in the groundmass Rock (1977,1984,1985,1986,1987) and Wimmenauer (1973) have synthesized the lamprophyre literature and have contributed much to the clarification of many of the problems that have long plagued these mafic-ultramafic rocks Rock (1986) has chosen to include lamproites as well as kimberlites in the lampro- phyre clan Although the term 'lamprophyre' is extremely broad and includes a host of interme- diate, mafic and ultramafic rock types, it is best utilized as a field term, for which it was originally intended, and should not be used to encompass such widely separated rock types as kimberlites and lamproites which possess such distinct evolutions Clearly, many basalts fulfil the defi- nition of' lamprophyre, yet basalts and lampro-, phyres are petrogenetically distinct (Rock 1987) However, Yagi st a1 (1975) described a lampro.. phyre dike which represents the subvolcanic feeder zone of allcali basalt flows

The original definitions of 'lamprophyre' have emphasized the shallow intrusive dyke character of lamprophyres L,amproites, as we have seen, characteristically occur as extrusives or shallow intrusives, and it is only the very old occurrences that expose deeper feeder-dyke levels Clearly, every volcanic edifice can generally be traced to a feeder dyke As lamproites often possess a feldspathoid (leucite) among the phenocryst population (e g SB, WKB etc), they do not qualify to be called lamprophyres 'Troger's (1935) use of the term 'lamproite' as an extrusive equivalent of lamprophyres that are rich in K and Mg (presumably minettes) should be aban., doned As discussed above and below and by Rock (1984, 1987) minettes and lamproites are geochemically and mineralogically distinct, al- though there are some overlapping features Therefore minettes and lamproites cannot be related by currently understood processes that could link an intrusive to a coexisting extrusive form Several, albeit extremely rare, minettes occur as extrusives (e g NHB and COL) (see above), but these are not lamproites as we understand them at present Nevertheless, it is possible that minettes may be nothing more than deep-seated equivalents of extrusive lamproite lavas The h c t that minettes are generally Palaeozoic in age (notable exceptions are the NHB, COL and KAJ minettes of Cenozoic age) and therefore have experienced more erosion than younger lamproites supports this view More work is required to solve this problem

It is therefore suggested that lamproites as well as kimberlites be excluded from the lamprophyre clan if only to remove some of the inherent genetic biases introduced by associating them

This opinion is shared by several other workers ( J B Dawson, personal communication, 1984; R Mitchell, personal communication, 1985)

Lampr oite geochemist1 y Rather than reproducing individual geochemical analyses, the averages and ranges (represented by standard deviations) of geochemical par- ameters for various rock suites are discussed in this section, recognizing the inherent biases introduced by such an analysis The literature sources for individual analyses are tabulated in Appendix 1 Of' the 275 analyses available for lamproites, the lamproite group average is weighted toward the MAP, WKB, PRA and L.H suites (i e 75% of the analyses come from 4 or 20% of the suites) The most apparent feature of the geochemical data is the extreme range in major-, trace-element and isotopic composition of individual lamproite suites and of lamproites as a group

I h e average majo~element compositions of lamproite suites and other ultrapotassic rock suites are tabulated in Table 4 Univariate frequency-distribution bar charts including all the lamproite major- and minor-element data are illustrated in Fig 20 These distributions are heterogeneous for all elements and ratios con- sidered, emphasizing the compositional complex- ity and variability of lamproites Some distributionsare approximately normalor slightly skewed (e g K,O, P205 and MgO); however, most elements possess frequency distributions that are bimodal or extremely skewed (e g SiO,, A120,, TiO,, FeO, CaO, Na,O, BaO, H 2 0 and Z,r02) Elemental ratios (e g: Mg number, K,O/ Na,O and K20/AI,0,) display distributions characterized by a high kurtosis

With the exception of a few elements, lam- proites overlap in major-element composition with kimberlites and lamprophyres (Table 4) The range in composition of lamproites (ex- pressed as the a~ithmetic meanf 1 standard deviation) overlaps with that of kimberlites ibr all major elements except K, Si, Mg and Al However, statistical comparisons of the two groups, Iamproites and kimberlites, using a general linear-models procedure, show that they are different in terms of all major and minor elements Lamproites can be statistically distin- guished from lamprophyres, as a group, with respect to all major elements, but most signifi-. cantly with potassium (general linear model F value, 840) and less so for CaO, FeO*, Al,O, ( E

(s!seq lua3 lad iq81am !aaq aI!ieTon) sal!oldure[ u! soqei [e,uama[a sno!ieh pue slualuo3 luarua[a-rou!m pue -ro~em lor sme12e1p uo!lnq!ils!p.i(3uanbaia 02 91 J

EOZlv ~O!S

0 I EL0 OSO SZO

10' H

S C B

values of 300-700) Of ail the lamprophyres, minettes approach lamproites the closest; how. ever, when non-diamondiferous lamproites are statistically compared with minettes (general linear models Student t test), the two groups differ in A120,, FeO*, CaO, MgO, Na,O, K 2 0 and TiO, at the 99 9% confidence level Figure 21 illustrates the compositions of all lamproites compared with kimberlites and lamprophyres in two ternary projections used for representing kimberlites and related rocks (Cornelissen & Verwoerd 1975) Although agreat dealof overlap occurs in both plots, lamproires occupy a rela- tively K,O-rich field in the K,O-MgO--Ai20, ternary which i:; not occupied by either kimber-, lites or lamprophyres In the FeO-Al,O,-Mg0 projection, lamproites are intermediate between kimberlites and lamprophyres In fact, with exception of Si, P, Ti, K, Fe and Ca, lamproites are compositionally intermediate between kim- berlites and lamprophyres (Table 4) Larllproites

( h i

FIG 21. Ternary diag~am showing the compositions of lamproites, lamprophyres and kimberlites projected on (a) the AllO,-MgO-FeO* and (b) the K20-- AI,O,-MgO plane (weight per cent)

have the highest average K,O, TiO, and SiO, and the lowest average CaO and FeO contents of any of these mafic-ultramafic alkalic rock types Lamproites are distinguished from kamafugitic rocks by distinctly higher S i02 and lower A1,O3 and CaO contents as well as by a higher degree of peralkalinity Figure 22 and Tables 4 and 5 emphasize this K,O-Si0, distinction between lamprophyres, iamproites and kimberlites as a group Alkali basalt compositions greatly differ from lamproites in that they are significantly enriched in A120,, Na,O and CaO, and depleted i n K 2 0 , MgO, SiO,, P,O,, BaO and 2x0, (Tables I and 5 )

Figure 22 illustrates the covariance of selected major elements and their ratios for individual lamproite suites and compares the average com- positions of kimberlites, alkali basalts, lampro- phyres and several lamproite minerals With few exceptions, the size of an individual lamp~oite suite field is positively correlated with the number of analyses of' the given suite, a feature which emphasizes the extreme variability in lamproite geochemistry. It should be noted that in nearly every plot, diamondiferous suites overlap with each other in composition In a plot of the degree of ultrapotassic versus per potassic character (Fig 22(a)) most lamproite suites individually show a positive correlation, as displayed by most rock types in Fig 1, although several (e.g ARG)show a slight negative correlation As observed in Fig 22(b), some of the WKB lamproites are the most perpotassic of all lamproites whereas the MAP suites contain some of' the least perpotassic lamproites Figure 22(c) displays the extreme ranges in both CaO and K,O contents for given suites; diamondiferous suites are characterized by the lowest CaO contents The nature of magmatic differentiation in lamproite suites is documented in a plot of Mg number versus SiO, (Fig 22(d)) In addition, the generally primitive character of lamproites is evident; lamproites possess extremely high Mg numbers for their relatively high SiO, contents compared with nearly all other rock types Although some suites display decreasing Mg numbers with increasing SiO, (e g WKB, HOL and LH), a trend that is expected to ~esul t from the fractionation of'mafic phases such as olivine, diopside and phlogopite, many lamp~oite suites possess trends that display very limited Mg number variation (less than 10) with extremely laige changes in SiO, (e g ARG, PRA, KAM and NWI) Therefore some mafic phase iiactionation can explain the SOl-Mg number variations displayed within some suites, but other types of differentiation (e g vapour-, phase transfer) or, alternatively, differences in source composition, pressure andlor temperature

are required to explain the chemical variations within other lamproite suites

Figure 22(e) illustrates the covariance of TiO, and K,O Lamproite suites can be divided into two groups according to their TiO, contents: one group with Ti0, < 2 mol %includes COR, NWI, PEN, LH and MAP, and the other with TiO,:. 1 5 mol% includes WKB, ARG, BOB, SB, MBAY, GSB, HP and HOI. Interestingly, the NWI, COR, PEN, LH and MAP suites also share the feature of occurring in a young palaeo- orogenic zone and are most probably depleted in TiO, (as well as Nb e tc) because of a Ti0,- depleted source, a feature shared by orogenic andesites and related rocks. The extreme enrich- ments in TiO, displayed by the WRB, CHE, BOB and SB suites must represent Ti0,-enriched source rocks

Normative composition

The average CIPW normative compositions for most lamproite suites are given in 'Table 7, bearing in mind the limitations of the CIPW normative calculations in describing phlogopite- and amphibole-.richrocks The averagelamproite consists of nearly equal amounts (by weight) of salic and femic normative minerals Almost half (43%) of the 295 lamproites that have been included in this data set are quartz normative; in fact, all suites for which more than five rocks have been analysed contain at least one quartz- normative rock Only eight of the 21 suites contain rocks with normative leucite, and nor- mative Kmetasilicate is present in small amounts because of the Ahdepleted character of lam- proites All suites but two contain at least a few rocks with normative feldspathoids L.amproites as a group are characterized by significant normative orthoclase (16-59 wt %, average 35 wt %) and femic minerals (33-81 wt %, average 51 wt %), but relatively low normative albite (O- 12 wt %, average 5 wt %) and anorthite (0-6 wt %, average 1 wt %) relative to nearly all other igneous rocks As with most peralkaline rocks, almost all lamproites contain normative acmite (average 2 5 wt %)

Compared with minettes, lamproites contain similar average amounts of normative quartz, orthoclase and nepheline but significantly lowei albite and anorthite, slightly lower clinopyroxene, andslightly higher orthopyroxene, acmite, olivine and leucite Lamproites as a group are somewhat more enriched in femic minerals than minettes

Despite the common occuIrence of' modal leucite in lamproites, many lamproite magmas tend to differentiate towards quartz-normative residua This is based on the natu~al evidence of

-rich zgneous rocks 149

the normative compositions of interstitial glasses and whole-rock samples of glassy lamproites (e g GSB (Sheraton & Cundari 1980), LH (Kuehner et a1 1981) and WKB (Wade & Prider 1940; Prider 1982)) In fact many leucite-bearing lamproites are SiO, saturated or oversatu~ated This differentiation trend can be explained by a small amount of phlogopite fractionation and additionally by the experimental work of Luth (1967) in the system kalsilite--fbrsterite-silica- water which demonstrated that the phlogopite liquidus surface bridges the forsterite-kalsilite thermal divide at 1 kb

Trace-element chemistry

A summary of the trace-element geochemistry of lamproites, compared with that of kimberlites, lamprophyres and alkali basalts, is given in Table 6 and Fig 23(a) All trace elements show an extreme degree of variance with coefficients of variation typically more than 50% and ottenmore than 100% If these extreme variations are ignored, some general conclusions can be drawn On average, lamproites have the highest incom- patible.element contents (e.g Rb, Sr, Ba, U, 21 and rareearthelements (REE)) and alkali basalts the lowest, whereas kimberlites have the highest compatible-element contents(e g Ni, CI, Co, Sc, 2 n and Cu) and alkali basalts generally the lowest L.amproites are more enriched in both compatible and incompatible elements compared with other ultiapotassic rocks With respect to the average K/Rb ratios, the various rock groups are ranked as follows: alkali basalts (150), non- diamondiferous lamproites (220), calc-alkaline and alkaline lamprophyres (180), kimberlites (160) and diamondiferous lamproites (85)

The average REE contents of lamproites, lamprophyres and kimberlites all overlap to some degree (Table 6 and Fig 23(a)), and all are markedly light REE enriched and heavy RE.E depleted compared with alkali basalts Although a large degree of overlap exists, averagelamproite REE contents generally exceed those of kimber- lites. The average ratios of light REE to heavy REE (La/L.u),,, are ranked as follows: lamproite (loo), kimberlite (90), ultramafic lamprophyre (47), alkaline and calc-alkaline lamprophyre (27) and alkali basalt ( l l ) , showing that lamproites contain the smallest quantities of' heavy REE (relative to light REE,) compared with these other rock types

Since the degree of elemental variation for these rock types is so great, overlap is generally observed incomparing the trace-elementcontents of the various rock groups Nevertheless, the

S C Bergmnn

DIAMONOIFEROUS SUITES AYE KIMBERLITE 15%)

A AVE LAMPROPHYRE (8W) d AVE ALKA1.I BASALT (4230)

. -. -- 7 0 10 ZU 30 40 50

( 0 ) K20 i Na20 (moles)

- OIAMONDIFEROUS SUITES AYE KIMBERL.ITE (550)

A AVE LAMPROPHYRE (8W) K20/AI2O3 i 2 A AVE ALKALI BASALT l4230l

/ 0 AVE UMPROlTE PHLOGOPITE 12291

( b ) 1\1203 (mole %)

- DIAMONDIFEROUS SUITES AVE KIMBERLITE (550)

A AVE LAMPROPHYRE (8Wl A AYE ALKALI BASALT (4230) 0 AVE LAMPROITE PHLOGOPITE 1229) O AVE LAMPROITE AMPHIBOLE (97)

COR - - - .. .- .. SB -- - n p

KAM - -- - - GSB

MBA" PEN - .- - - NWI --- --- ppN -. - MAP , , ,

HOL

LH EN0 .--+cl-,

CHE -a?--+, NSW -r\nnn̂ N

0 10 a

( c ) C ~ O (mole %I

L,amproltes and K-rzch zgneous rocks

. ARG

OIAMONOIFEROUS SUIT

A AVE LAMPROPHYRE (8W) n AYE AI.IV\LI BASALT (4230)

30 40 70

10 - DIAMONOIFEROUS SUITES

AYE KIMBERLITE (5%) A AVE MMPROPHYAE /8W) n AVE ALKALI BASALT (4230) 0 AYE LAMPROITE PHLOGOPITE 1229) 0 AYE LAMPROITE AMPHIBOLE (91)

5

COR - - - ... - - SB --- n p - - -- --

KAM - - - .. GSB - - - -. - -

,,,BAY PEN -- -. NWI -. - - - -. -. PPN

MAP HOL -- . . .. - .. .. .

LH EN0 -I+,,--+

CHE --'d+ NSW Yhlvururr*.

0 5 10 15

( e ) K ~ O mole %J

. . , . , . . veIsus K?O/N~,O; ( b j ~ , ~ versus A~,o,; (C)K,O versus CaO; (d) Mg number versus SiO,; (e) TiO, versus K,O

trace elements that are most useful in distinguish- ing lamproites from kimberlites are as follows: (a) Rb, SI, Ba, Zr and the K/Rb ratio; (b) Ni, Cr, Co and the Ni/Cr ratio Kimberlites generally have Rb.: 150 ppm, Sr < 1200 ppm, Ba i 3000 ppnl, 21 1800 pprn and K/Rb < 150, whereas lamproites generally have Rb > 150 ppm, Sr > 1200 ppm, Ba> 3000 ppm, 21 > 800 ppm and K/ R b > 150 With respect to the compatible ele- ments, kimberlites generally have Ni > 500 ppm, CI > 800 ppm, Co> 50 pprn and Ni/Cr:.O 7, whereaslamproitesgenerally have Ni < 500 ppm, CI < 800 pprn Co < 50 pprn and N~/C:I.< 0 7 In general, the absolute concentrations of both compatible and incompatible elements are larger

in kimberlites and lamproites than in alkali basalts and lamprophyres

Individual lampsoite suites show widely-rang- ing trace-element abundances The Indian lam- proites (CHE, GDW) are the most enriched in REE of all lamproites yet contain typical lam- proite signatures with respect to the other trace elements Lamproite suites possessing the lowest LIL,-element contents include KAM, NWI and ARG

On the basis of the available data diamondif'er- ous lamp~oites display no statistically-significant diilerences relative to bassen lamproites in their trace-element systematics, with the exception of an enrichment in Nb and Ga and in the

152 S C Bergman

TABLE 7 Average L'IP Wnormatri~e composrtzons ojiia~rour Iamprorte and related rock sirrter

ARG 3 BOB I CHE 2 COC 2 COR 2 E M 4 GSB 1 HLM 2 HOL 12 H P 4 KAM 9 LH 24 MAP 99 MBAY 6 NWI 9 PFN I

WKB 5 1 Lamprolte 284 Mlnette 50 Lamprophyre 728

Suite n 01 mt il hm SD rt ap cc J' Foid 7 Salic 7 Femic

ARG 3 1791.159 3 l j 1 5 5'71-08 -- .. 3 0 + 0 9 2 6 1 . 1 9 0 6 33 9 66 I BOB I - - - 7 2 - 5 9 4 1 4 1 54 4 48 6 -

CHE 2 3 5 + 4 8 3 4 1 0 2 1 1 3 1 - 0 1 0 3 1 0 5 -- .- 4 9 + 0 2 1 3 0 1 . 2 9 - 19 0 81 0 COC 2 2 0 9 1 4 6 39-i .34 1 6 + 0 1 - - .- 1 4 1 0 2 0 5 1 . 0 7 5 7 44 2 55 8 COR 2 1 3 + 1 8 0 9 + 1 3 2 4 1 - 0 3 - - - 1 5 1 - 0 7 2 9 1 . 2 8 0 3 65 3 34 7 EVD 4 2 6 7 1 3 3 2 8 + 0 4 381 -06 - - - 7 0 + 4 8 - 16 6 44 I 55 9 GSB 1 11 3 - 6 6 .- - - 3 6 0 2 5 7 54 9 15 1 HLIM 2 1 4 3 + 5 4 211 .30 351 -07 2 8 1 3 9 -- - 6 6 + 2 3 0 1 1 . 0 ! - 66 8 33 4 HOL I2 2 2 7 + 1 3 8 - 6 4 + 1 3 - - -- 2 9 ~ 0 8 1 0 0 + 3 5 3 7 40 6 59 4 H P 4 2521.158 - 5 8 + 0 6 - - - 1 8 + 0 S - 2 5 32 1 67 9 KAM 9 861.140 1 5 1 2 9 3 0 1 - 1 0 1 4 + 2 0 1 5 + 1 5 -. 3 0 1 0 7 0 1 1 0 2 6 0 55 0 45 0 LH 24 6 5 f 4 . 4 0 2 1 0 8 2 6 + 1 2 181 -21 1 7 i . 2 0 -- 3 6 + 1 3 0 5 1 . 1 4 1 2 5 55 5 44 5 MAP 99 741.102 1 0 1 1 4 2 3 + 1 2 1 2 k 2 1 0 7 1 . 1 5 0 0 2 + 0 1 2 5 + l l 1 2 i . 2 6 I 0 58 0 42 0 MBAY 6 - O l i O l 7 3 1 . 1 9 0 6 1 0 8 0 1 1 . 0 3 - 6 5 1 . 1 7 0 8 1 1 3 1 6 54 8 45 2 NWI 9 I l 11.11 l 1 2 1 . 1 3 2 4 + 0 4 - - 2 9 5 0 3 - 3 2 52 4 47 6 PEN I 2 8 3 2 - - - - 4 3 6 2 0 4 60 9 39 I PRA 24 174k20 .7 1 8 + 3 1 3 7 1 - 1 7 1 7 1 . 3 2 0 1 + 0 4 0 6 1 0 7 2 5 1 - 1 7 4 4 1 - 3 0 0 8 26 5 73 5 SB 13 0 7 + 1 8 - 8 6 + 3 3 0 6 + 1 2 2 3 1 . 3 5 0 1 1 0 4 4 1 1 2 1 3 9 + 6 . 3 0 8 56 6 43 3 WKB 51 781.140 0 6 1 . 1 7 5 0 + 3 0 3 1 + 2 6 3 5 ~ 3 4 10115 2 6 1 1 4 26-i.10.2 3 8 45 5 54 5 Lamproite 284 9 9 k 1 2 . 6 1 3 ~ 2 2 4 3 1 . 2 9 171 .25 l i t 2 3 0 3 i 0 8 2 9 1 . 1 6 2 2 1 . 5 7 4 3 48 7 51 3 Minette 50 6 2 k 6 . 3 3 6 f 2 5 3 3 1 - 2 0 1 3 1 2 5 0 . 2 + 0 8 0 0 2 + 0 1 2 7 f 2 I 211 .39 2 0 59 0 41 0 Lamprophyre728 1 0 4 + 1 0 0 5 4 k 3 3 4 4 1 - 2 8 1 4 + 3 8 0 0 3 k 0 4 O l i o 6 1'11.13 2 2 2 5 0 8 4 49 9 50 I - Means I standard deviations are given for n >. 2 analyses: weight per cent normative minerals; only those mir~crals which occur in significant concentrations (i e more than 0 1 wt) are tabulated here Noims are calculated using the reported FcO and Fe,O, contents

compatible elements (Cr, Ni, Co) However, (e g U, Th and Zr) and among the lowest Rb diamondiferous lamproites possess slightly contents of any lamproite. WKB are likewise higher average light REE (La, Ce), Rb, Ba and exceptionally enriched in LIL elements T'a contents and have higher LaILu (1400 com- pared with 8001, B ~ / S I . (ZcompaIed with 13) and Stable and radiogenic isotopic geochemistry of much lower K/Rb ratios (85 compared with 220)

Ultrapotassic magmas relative to ba~ren varieties SB magmas contain among the highest REE, Sr and Ba contents of Sr and/or Nd isotopic ratios have been measured all lamproite-suites, but possess more typical in rocks f ~ o m ei!ht lamproite suites (over 160 lamproite concentrations of other LIL. elements samples) and in e~gh t potassic-ultrapotassic rock

, , 1 , ' , , , , , , , , , , INCOMPATIBLE ELEMENTS

$000 -

Barren Lampioller

.m 4 caic Aikailne & ~ ~ k a i i n e iampropnvrer

COMPATIBLE A N D OTHER TRANSITION ELEMENTS

10 I I

1 0 -

010-

I

FIG. 23. (a) Spider diagram show~ng the average abundances oi a wide variety o fcom~at ib le and incompatible elements in varloiis rock groups normaiized to estimated abondances in the primitive mantle of Taylor & McLennan (1981) plotted against an arbitrary orderlng of elements which grossly ranks geochem~cally related elements in terms of t l le~r bulk mantle- melt parrlrion coeffic~ent; (b) present-day "'Nd/""Nd versus s7Sr/s6Sr ratios for various iamproite sujtes and con~positionaliy related rock groups (after Mitchell & Hawkeswortli 1984). See text for discussion and Tables 2 and 3 for abbreviations.

I54 S C Bergman

suites other than lamproites (over 200 samples); the results are summarized in Tables 8 and 9 and Fig 23(b) Whereas ultrapotassic rocks other than larnproites generally fall in the ianges "Sr/ 86Sr, = 0,704-0 708 and r"3Nd/1"4Nd, = 0 5122- 0 5126 (where t indicates present-day ratios), lamproites are characterized by much more and much less radiogenic compositions respectively, with 87S~/86Sr,=0 705-0 718 and r43Nd/ "%d,=O 51 12-0 5123 L.amproite Nd-SI is@ topic data fall along two district trends on an E,,-

eS, plot (Fig 23(b)) One trerd, which includes the SB and LH suites, is characterized by slightly radiogenic 87Sr/86Sr ratios with extremely n o n radiogenic r43Nd/r4'Nd ratios, and another shallow trend, which includes GSB, MAP and WKB rocks, is characterized by extremely radio- genic 87Sr/8%~ ratios and non-radiogenic r43Nd/ 144Nd ratios (Table 8). These data indicate that the source regions of these mantle-derived mag- mas were characterized by very old rocks (more than (1-3) x lo3 Ma old) with Rb/Sr and Nd/Sm ratios greater than those of bulk Earth, the former source material possessing slightly lower Rb/Sr ratios or being younger than the latter Most important is the undeniable conclusion that the source regions of primary mantle-derived d i a

mondiferous melts (e g Ellendale) may be ex- tremely old and enriched in Rb relative to Sr and Nd relative to Sm In the past it has generally been assumed that basalts possessing relatively high " S I / ~ ~ S I ratios (above 0 7050) (Faure & Powell 1972; Faure 1977) must have been contaminated by radiogenic continental crustal material during their ascent Howevei, combined with the SI-Nd isotopic data on some kimberlites and included megacrysts and xenoliths (Menzies & Murthy 1980a, b ; Erlank et a1 1982; Hawkes. worth et a1 198'3; Kramers et a1 1983; Smith 1983a, b), the lamproite data indicate that contamination by continentalcrust isnot required to explain their isotopic systematics and that extremely enriched portions of the sub..continen- tal upper-mantle lithosphere exist

Oxygen isotopic studies have thus far been largely limited to ultrapotassic rocks other than lamproites, with the exception of the 1.H and GSB suites Studies by Garlick (1966), Taylor (1968), Barberi er a1 (1975, 1978), 'Iaylor & Turi (19'76), Turi & Taylor (1976), Taylor er a1 (1979, 1984), Ferrara e ta1 (1980, 1985), Kuehner (1980) and Kyser eral (1981) demonstrate thatunaltered lamproites generally possess slightly higher 6"0 ratios (7-12) compared with typical mantle-

TABLE 8 Sr and Ncl irotoplc tomposztions ojlamproites

Local~ty* 87Sr/86Sr, " 3 ~ d / ' J ' N d , Reference -- -

n i Range n i Range

WKB

L H

MAP

PRA

NWI

GSB

SB

NSW

WKB

SB

MAP

* See Tables 2 and 3 and text for abbreviations 1, Kaplan et a1 1967; 2, Powell & Bell 1970; 3, Nixon er a1 1984; 4 , McCulloch er a1 1983a. b ; 5, Jaques et a1 1984a; 6, Vollmer erai. 1984; 7, Bolivar 1977; 8, Smith 1983b; 9, Venturelli eral 198?a, b ; 10, iollerson & McCulloch 1982; 11, Mitchell & Hawkeswoith 1984; 12, Mitchell, personal communication, 1984: 13, Fraser e t a1 1985; 14, Nelson er a1 1986

Lamproztes and K-rzch zgneous rocks I 5 5

TABLE 9 Sr and Nd isotopic compositions ojultrapotasr~c-potassic rocks other than lamproites

L.ocality* Rock type 87Sr/86Sr, 143Nd/'4'Nd, Reier- ence

n i Range n X Range -

HM Shonkinite etc 10 0 7078 0 70'72-0 7087 1

NHB Minette, monchiquite 12 0 7062 0 7041-0 7081 1 etc

TAN Kamaiugites, ugandite, 104 0 7059 0 7036-0 7083 2 kivite, shoshonite 8 0 7047 0 7046-0 7048 4 0 5127 0 51270-0 51272 7 etc 37 0'7069 0 7046-07103 12 0 51250 0 51211-0 51276 4

0 7035-0 7096 5 6 0 7057 0 7054-0 7059 18

TUSC Kamafugitcs 1 07112 - 6 1 07104 7

LAC Basalts 9 0 7054 0 7046-0 7062 7 - 8 , 9

0 7044-0 7047 ? -- 0 51260-0 51265 10 RP Basalts, intermediate 22 0 7092 11

and felsic rocks 17 0 7085 0 7068-0 7098 12 14 07097 0 7085--0 7111 8 051212 051209-051216 17

CSN IJltrapotassic and po- 5 0 '7064 0 7061-0 7068 14 tassic basalts

DSV L,eucitite 2 0 7119 07119-0 7124 14

NSW Leucitite 11 07053 07050-0705'7 11 05118 05116-05119 16

S Airican kimberlites Group I 24 0 7057 0 70'3-0'706 8 0 51276 0 51257-0 51282 15 Group I1 28 0'7088 0 708-0 710 6 051219 051213-051234 15

N American kimberlites Group 1 13 0 7945 0 704-0 705 15

Finsch I1 7 07100 0 7095-0 7119 6 0 51219 051217-0 51224 17 - -- -- * See Tables 2 and 3 and text for abbreviations 1, Powell &Bell 1970; 2, Bell &Powell 1969; 3, Voilmer & Norry l983a; 4, Vollmer &Norry 1983b; 5, Rock 1976; 6, Holm& Munksgaard 1982; 7, Vollmer 1976; 8, fioefs & Wedepohl 1968; 9, Hurley era1 1966; 10, Staudigel & Zindler 1978; 11, Powell & Bell 1974; 12, Cox era1 1976; 13, Rogers ern1 1985; 14, Van Kooten 1981; 15, Smith 1983b; 16, Fraser er a1 1985; 17, Nelson eta1 1986; 18, Aoki & Kurasawa 1984

derived material and support the following conclusions: (a) in regions such as the Roman Province (RP), where isotopically heavy crust exists (6180= + 15 to +25), contamination by crustal material is required to explain the stable isotope compositions, and SI and Nd isotopic compositions are also probably modified by crustal contamination (Taylor et a1 1984); (b) some lamproites (e g GSB) and other ultrapotas- sic rocks (e g. 1AN)dispIay primary mantle6'80 signatures (about + 6 5) when corrected for near- surface alteration effects (Taylor et a1 1984); and (c) the source regions of some ultrapotassic magmas do not substantially differ in their 6180 compositions from those of typical mid-ocean ridge basalts (MORBs) (about + 5 5) or kimber- lites and the i~ xenoliths ( f 5.5 to f 7 5) (Taylor 1968; Kyse~ et a1 1981, 1982) It is also possible that lamproite source regions are anomalous in t h e i ~ 6180 systematics compared with other mantle rocks

Pb isotopic studies are similarly largely r e . stricted to ultrapotassic rocks other than l a m proites Most Pb isotopic data exists for the TAN, RP, CSN and DSV suites (Vollmer 1976, 1977; Van Kooten 1981; Vollmer & Norry 1983a, b) and suggest that, in the first case, a Pb-Pb model age of 500 Ma dates a mantle-source homogeni- zation event (metasomatism?) Pb isotopic sys- tematics of the R P rocks, however, are most consistent with the mixing of two distinct reservoirs; this interpretation is also consistent with the oxygen isotope data noted above Van Kooten's (1981) Pbisotope worksuggests a rather recent mantle-homogenization event on the basis of large variations in 238U/206Pb and 232Th/ '08Pb ratios with rather restricted ranges in 207Pb/202Pb, 206Pb/204Pb and 208Pb/204Pb ra- tios, perhaps as recent as 10 Ma ago Pb isotopic studies on lamproites from LH and SB are currently under.way at the Open University (e.g Fraser et a1 1985) and on WKB rocks at the

Australian National University (e g Nelson et a1 1986) and tentatively indicate model ages of (1 5-3 0)x 103 Ma for these mantle source re- gions

Further radiogenic and stable isotope studies are clearly required for a better understanding of the petsogenesis of lamproites For example, are the two trends recognized thus far in terms of'^^,- cNd systematics simply the result of too few samples, and will these two trends develop into one broad tr'end for more lamproite suites? Are all lamproites characterized by 'enriched' Sr and 'depleted' Nd isotopic signatures in contrast with the vast majority of isotopically 'depleted' signa- tures commonly observed in alkali basalts and MORB (Hofmann et a1 1979)?

Lampr oite mineral chemistry 'The mineralogy and mineral chemistry of lam- proites has been recently reviewed by Mitchell (1985) and Wagner & Veide (1985), to which the reader is referred for detailed accounts Therefore only themost important features, abstracted from Mitchell's review, will be highlighted in this section, and the mineral chemistry oilamproites will be compared with that of associated rock types An important feature oflamproite mineral compositions is that they reflect the exotic compositions of the magmas from which the minerals crystallized A tabulation of literature containing lamproite-mineral chemical data can be found in Appendix 2 The average Iamproite and related sock mineral compositions are pro- vided in Table 10

Olivine

Olivine (commonly pseudomorphed by secondary phases) occurs in two generations (large anhedral macrocrysts (dimensions of more than 1 mm) and small strain-free crystals or aggregates (dimen- sion of less than 1 mm)) in the more mafic members (and some felsic members, e g MAP) of nearly all lamproite suites The compositional range observed for both types is F O , , - ~ ~ with most about Fo,, NiO contents are typically in the range 0 15-0 6 wt %whereas CaO is generally less than 0 2 wt % The Mg numbers and CaO and NiO contents of lamproite olivines overlap those observed in kimberlites and lamprophyres but are distinct from those in alkali basalts and related sock types

Orthopyr oxene

Orthopyroxenes ranging in composition f ron~ En,,toEn,,(Cr203~01wt%;Ca0.:1 3 w t % ;

TiO1<O 4 wt %) occur in the MAP, LH and WKB suites Their extremely wide range in Mg number and texture (commonly rimmed by phlogopite) suggests that some may be xenocrys., tic; however, their extremely low AI20, contents (typically less than 1 0 wt %), are much lower than those observed in orthopyroxenes from mafic igneous rocks and suggest some type of lamproite affinity The~efore many of the Fe-rich orthopyroxenes most probably originate by div aggregation of phlogopite-pyroxene or other cognate xenoliths

Clinopyr oxene

Either diopside or salite has been observed in virtually every lamproite; most clinopyroxenes are nearly pure diopside-hedenbergite solid so. lutions (22-26 wt % CaO) The A1,03 contents in lamproite clinopyroxenes are remarkably low (average 0 5 wt %)relative to clinopyroxenes of other mafic and ultramafic volcanic rocks (less than 5-10 wt % A1203), except those in some kimberlites (1--2 wt %); in fact, many lamproite clinopyroxenes have insufficient Al to fill all the tetrahedral sites Anomalously high A1,03 con- tents in some lamproite diopsides (less than 1.0 wt %) are interpreted as indicating a xenolithic relationship or contamination, based on the compositions of grains in both the groundmass and phenocryst populations of the bette~studied localities (i e LH, WKB and HOL) Lamproite diopsides typically contain 0 4-3 5 wt % Ti02 (HP with the highest content, PRA with inter.. mediate content, and MAP and LH with the lowest content), 0 0-1 5 wt % Cr20, (LH and HP with the lowest content, and WKB and PRA with the highest content) and 0 0-1 5 wt % N a 2 0 (genesally 0 3-0 4 wt %) Of all the mafic and ultramafic rock types, lamproites contain diop- sides with the lowest NazO contents It is therefore remarkable that aegirine occurs on the rims of' diopside grains, especially those within vesicles, in LH rocks (Kemp & Knight 1901; Carmichael 1967; Kuehner 1980) and other lamproites (Wagner & Velde 1985) Clinopyrox- enes found in some kimberlites and some ultra- mafic lamprophyres are similar in composition to those found in lamproites

Alkali amphiboles

K-Ti-richterite is a common alkali amphibole observed as late..stage groundmass grains in most larnproite suites (e g HOL,, WKB, LH, SB, HP, PRA and GSB), although K-Ti-Mg-arfvedson- ites and K-siebeckites also occur (e g at PP,

Larnproltes and K-rzch zgneou5 rocks 157

T A B L E 10 Summary ojmineraithemirtry oflamprortepharer compared with thoreofother rock typer*

Groondmass, phenocryst phases Xenocryst, xenolith phases - - LAMP LAMPH KlMB AOB ALK KIMB AOB LAMPH

n 58 I3 150 78 14 552 319 51 SiO, 4 0 1 1 40f 1 4 1 4 1 3 8 2 2 39 41 + 2 40+ 1 40+1 TiO, 0 0 0 03 0 02 0 03 0 07 0 03 0 02 0 07 Al,O, 0 0 5 0 03 0 03 0 03 0 04 0 04 0 17 0 02 Cr,O, 0.03 0 04 0 06 0 01 0 06 0 04 0 0 4 0 0 5 FeO* 1 0 + 3 1 2 + 5 9 + 2 22+9 20 9 + 3 12+5 l o + 2 MnO 0 17 0 24 0 11 0 35 0 30 0 I1 0 17 0 15 NiO 0 3 3 + 0 1 0 . 39+07 0 .32+0 I 0 1 3 + 0 11 0 2 4 0 3 5 + 0 1 0.28+0 1 0.34+0 14 MgO 49+2 4 7 + 5 50+2 3 9 2 8 40 5 0 f 3 4 7 + 4 49+2 CaO 0 1 7 + 0 2 0 16+0 1 0 07+0 8 0 30+0 1 0 4 2 0 5 f 0 6 0 .11+0 1 0 0 7 + 0 6 Total 99 9 100 r 100 2 99 8 99 8 100 2 100 0 100 2 Mgno 8 9 1 3 87+6 9 1 + 3 7 5 2 1 2 77 90+3 8 7 f 6 9 0 f 2

Orrhopyrorener -- --

Groundmass, phenocryst phases Xenocryst, xenolith phases -.

LAMP LAMPH I N 1 LAMP LAMPH KIMB AOB -- .-

n 7 7 37 6 95 657 380

~ 1 ~ 0 , 0 9 ~ 1 6 1 3 1 f 0 5 0 5 0 1 3 + 0 9 2 7 + 7 1 4+7 3 9 ~ 7 5 Cr203 0 29 0 9 - 0 3 2 f 0 3 0 3 6 + 0 2 0 3 3 f 0 2 0 3 6 2 0 2 FeO* 12+6 5 + 1 21 7 + 6 7 f 2 6+12 8 2 4 MnO 0 27 0 10 0 56 0 24 0 16 0 13 0 17 NiO - - 0 12 0 10 0 09 0.08 -

MgO 30 33 24 CaO 1 0 + 0 4 2 2 + 0 . 8 1 2 Na10 0 l l 0 1 2 f 0 1 - 0 1 & 0 8 0 1 ~ 0 1 0 1 3 f 0 1 0 1 0 f 0 8 Total 99 7 99 6 100 1 99 8 100 4 100 I 99 8 Mg no 81+10 92+2 67 89f 10 8 9 t 4 90+6 88+7

Groundmass, phenocryst phases Xenoc~yst, xenolith phases --- -

LAMP LAMPH INT AOB ECL ATP ALK KIMB AOB LAMPH

n 118 5 3 SiO, 5 3 1 2 40+ 3 110, 4 5 + 2 4 3 k l A120, 0 8 + 1 7 1 3 f 3 Cr,O, 0 0 3 2 0 5 0 0 2 + 0 2 FeO* 8 f 7 1 3 + 4 MnO 0 3 9 + l 0 4 1 + 0 5 NiO 0 0 4 1 0 4 - MgO 17+5 1 2 + 3 CaO 51.2 11+2 N a 2 0 4 9 + 1 5 2 5 + 1 KzO 4 2 f 1 6 1 4 + 0 6 BaO 0 1 7 + 0 2 - Total 97 1 97 6 Mgno 7 8 f 2 0 6 2 f 1 3

S C Bergman

TABLE 10 (tont ) Summa~yojmrneralchemrstry ojlamprortephaser cornpaled wrth thoreojother lock types*

Clinopyro xener - -

Groundmass, phenocryst phases Xenocryst, xenohth phases - -- - LAMP LAIMPH KIMB AOB ECL A I P INT ALK LAMP KIMB AOB LAMPH

n 158 128 188 175 86 115 31 135 24 1057 724 233 SIO, 5 3 f 1 5 0 f 1 5 4 f 2 48f 3 55 57. 52 49 5 4 f 1 5 54+1 5 5 1 1 2 53+3 1 Ti0, 1 0 f 0 6 1 6 1 1 0 4 2 + 0 5 2 4 + 1 0 1 9 0 3 9 0 5 7 1 1 0 5 5 + 0 3 0 2 8 f 0 2 0 8 0 ~ 0 8 0 7 0 + 0 7 A1,0, 0 5 1 + 0 7 4 2 f 2 7 3 5 + 3 ? 6 0 3 8 2 4 8 2 6 1 8 1 2 f 1 2 4 6 1 4 1 L 0 f 2 6 0 + 3 Cr,Ol 0 1 9 + 0 3 0 1 4 + 0 1 0 8 f l 0 2 f 0 2 0 8 0 7 2 0 1 2 0 1 0 0 9 f 0 8 1 0 1 0 9 0 7 f 0 5 0 5 1 0 6 FeO* 3 5 f 2 6 8 f 3 4 2 + 2 8 5 + 3 6 8 2 8 8 5 10 4 8 f 3 3 3 6 i . 1 9 5 0 t 2 4 5 2 + 2 5 MnO 0 1 1 + 0 7 0 2 1 + 0 ? 0 1 1 + 0 1 0 1 9 + 0 1 0 5 0 8 0 2 5 0 3 7 0 2 9 0 1 0 01,- 0 1 1 N10 0 0 6 ~ 0 4 0 1 2 ~ 0 1 0 0 3 f 0 2 0 0 3 T 0 3 0 4 0 4 0 1 0 6 0 8 0 6 MgO 17+2 1 1 + 3 1 6 f 3 1 2 + 3 9 2 16 15 12 16+2 1 6 1 4 CaO 2 4 1 2 22i.3 19+4 2 1 1 3 14 22 21 22 23+2 1 8 2 3 N a 2 0 0 4 6 + 0 7 0 8 + 1 2 2 + 1 7 1 0 + 1 6 6 0 1 0 0 3 7 1 3 0 8 7 + 0 5 2 6 + 2 Total 99 7 99 8 99 7 99 T 9 9 6 9 9 8 9 9 6 9 9 7 1 0 0 0 9 9 9 Mgno 9 0 + 7 7 8 + l l 8 7 2 8 7 2 f l 3 69 91 77 67 55+10 8 8 f 7 wo 47 5 46 2 42 0 47 1 44 2 46 5 42 2 47 2 46 6 42 4 en 47 0 42 4 50 4 35 0 39 0 48 8 44 2 35 5 45 6 50 9 fs 5 5 11 4 7 5 14 9 1 6 7 4 7 1 7 6 1 7 7 7 8 6 7

Spmelr -- --- -. -

Groundmass, phenocsyst phases Xenocryst, xenolith phases

LAMP AOB KIMB LAMPH ATP LAMP AOB KIMB LAMPH

n 25 3 7 253 29 45 I 3 337 503 48 BO, 0 2 0.2 0 2 0 2 0 1 0 2 0 2 0 2 0 2 TiO, 9 1 1 8 f l l 10+8 10+7 0 1 1 .3+3 2.8+8 4 3 i - 7 1 . 6 1 4 A120, 3f 3 S t 8 9+12 8+11 28+11 17+11 42+20 16+16 39+22 Ci,O, 3 7 f l 8 7 f 1 3 20+23 1 7 1 1 9 39+10 4 5 5 1 1 1 7 f 1 5 3 6 f 2 2 2 3 1 1 9 FeO* 4 1 f 1 9 61+14 4 5 f 2 3 5 9 f 2 1 19+8 2 2 f 1 2 21 f18 2 9 f 2 0 1 9 1 1 5 MnO 0 9 f 0 4 0 7 + 0 4 0 6 5 0 4 0 5 f 0 6 O 3 f 0 1 0 6 f 0 3 0 3 + 0 2 0 4 + 0 3 0 2 f 0 2 NiO 0 1 f 0 1 0 1 + 0 1 0 1 + - 0 1 0 2 1 0 1 O . l f 0 I 0 2 + 0 1 0 . 4 + 0 9 0 2 + 1 0 . 4 2 0 2 MgO 8 + 3 5 + 5 11+6 7 + 5 13f 3 1 3 + 3 1 7 f 5 l 3 + 5 17+5 YzO, - 0 . 4 1 0 2 0 . 5 5 0 3 0 .2 i . 01 .- 0 .3+0 3 0 1 + 0 3 0 6 + 0 3 0 5 'Iotai 98 97 97 97 99 99 99 99 99

llmenites

Groundmass, phenocryst phases Xenocryst, xenollth phases

LAMP KIMN LAMPM AOB KIMB LAMPH AOB ..FA-- -

MgO 3 3 + 0 5 92;s 3 8 + 4 5 1 f 2 l o g 3 9 5 f 3 7 6 ~ 7 CaO 0 1 0 1 5 i 0 2 0 2 6 1 0 3 0 3 5 0 0 4 1 0 0 5 0 0 5 + 0 5 0 0 4 5 0 2 Total 99 98 99 99 98 99 98

Lamproztes and K-rzch zgneous rocks I59

T A B L E 10 (cant ) Summary ojmmerai chemzstry ojlampro~tephaser compared wlth those ojother rock type$*

Groundmass, phenoctyst phases Xenolith, xenociyst phases

LAMP LAMPH KIMB I N 1 ATP ALK KIMB AOB LAMPH

n 258 Si02 41 t 2 TlO, 5 0,2 A1,0, 10+ 3 Cr201 0 3 + 0 4 FeO* 6 8 + 4 MnO 0 0 6 N10 0 11 MgO 2 2 f 3 CaO 0 07 Na,O 0.30 K,Z) 10+0 6 BaO 0 8 + 0 6 Total 95 2 Mgno 85+10

Santdlnes (or alkalr feldspar)

LAMP LAMPH -

LAMP LAMP

n 28 16 15 20 S10, 63+1 6 5 2 2 SIO, 56 0 SIO? 0 1 A1,03 1 7 2 1 19+1 A1,0, 21 0 T i 0 2 71 S + 2 Fe20, 2 3 + l 0 3 + 0 1 Fe,Ol 1 2 AI,O, 0 5 + 0 9 MgO 0 5 f 0 4 0 0 1 CaO 0 01 Ci20, 0 5 + 0 1 MnO 002 . 0 01 N a 2 0 005 FeO 9 1 + 3 CaO 0 2 5 2 0 4 0 2 4 f 0 3 K,O 21 3 CaO 0 0 4 Na,O 0 4 7 f 0 2 36i .5 99 6 Na,O 0 38+0 2 K2O 1 6 f 0 5 1 1 2 5 K2O 7 7 + 1 6 BaO I f 0 7 0 5 BaO 9 8 + 5

99 99 99 a Garnets

Xenociyst, xenolith phases

L.AMP KIMB LAMPH AOB

c~;o; ?]-ti 3 1 2 2 2 0 8 > l FeO* 12+9 1 1 2 5 12+4 11 2 5 MnO 1 1 + 1 3 0 3 8 + 0 2 0 4 + 0 2 0 3 5 + 0 1

MgO 18f6 I S + ? 1 7 f 4 l S k 4 CaO 4 5 i . 1 6 6 + 3 6 3i.3 5 5 + 1 Na,O 0 01 0 0 8 + 0 2 0 6 2 0 8 0 0 5 + 0 1 Total 100 0 100 1 100 3 99 9 Mgno 72+22 74214 7 1 f l l 73214

* LAMP, lamproites; L4MPH, lamprophyres; AOB, alkali olivine basalts; KIMB, kimberlites; I N I , intermediate volcanic rocks (e g andesites); ALK, alkaline plutonic iocks; ATP, alpine-type peridotites; ECL, eclogites All major.element analyses in weight per cent FeO*, total Fe as FeO

I 60 S C E

MBAY, SB, WKB, HOL and NWI) The fact that many so-called K-richterites iromlamproites possess K,O/Na,Omolar ratios of less than unity is consistent with this late-stage interpretation Amphibole also occurs as late-stage euhedral crystals lining vesicles in some lamproite lavas Lamproite amphibole compositions vary widely with the f'ollowing typical ranges: Mg number, 40-94;A1203,0 0-1 5wt%;TiO,, 1-7wt %(Fig 24) As with lamproite clinopyroxenes and phlo- gopites, there is usually insufficient A1 to fill all the tetrahedral sites in Iamproite amphiboles. Individual K-richterite grains are typically zoned with rims displaying enrichments in Ti, Na and Fe and depletions in K and Mg relative to the cores Therefore many of' the more evolved amphiboles (e g some of those in MAP, PE:N, MBAY. WKB, PP, SB and HOL) display K,O/ N a 2 0 < 1 (molar) The most potassic richterites (K,O/Na,O> 1 5 (molar) occur in the WKB, HP and PRA suites In contrast with the extremely titaniferous phlogopites in the SB suite (more than 10 wt % 'TiO,), SB amphiboles have TiO, contents (3-4 wt %)similar to those in the average Iamproite 'The MnO contents of lamproite amphiboles are similar to those of lamprophyres but are significantly higher than most composi- tionally-similar rock types.

K-richterites are also found in some K..rich ultramafic rocks previously thought to be kimber.. lites (Baster's mine, Pniel, Barkly West (Erlank 197'3); this rock is considered a lamproite in the present study) and in MARID-type xenoliths (Dawson & Smith 1977; Erlank & Richard 1977; Dawson 1979); however, these tend to bedepleted in T i relative to lamproite amphiboles Relative to nearly all other related rock types, lamproite amphiboles are compositionally unique, being the most depleted in A1 and Ca and enriched in K, Ti and Si

Mason (1977) studied the geochemistry of K- richterites from Wolgidee Hills, Western Aus- tralia, and found that they are extremely depleted in REE relative toother amphibolesfiom alkalic- mafic magmatic settings This REE depletion is in agreement with the interpretation mentioned above, i e that K-richterite precipitated rela- tively late in the crystallization sequence follow- ing the crystallization of' REE-enriched phases such as apatite

Phlogopite

Ti-rich AI-poor phlogopites and tetraferriphlo- gopites of widely-varying compositions occur as an essential phase in all lamproites, as both phenoc~yst and/or groundmass phases Grains with Al-deficient tetraferriphlogopite margins,

often demonstrating a reverse pleochioic for- mula, are common in both phenocryst and poikilitic groundmass grains The characteristics of lamproite phlogopites are generally as follows: Mg numbers, 37-94; TiO,, 2-1 1 wt %; Cr,03, 0 0-1 5 wt %; Al,O,, 1-14 wt %; SiO,, 18- 43 wt % Extreme zoning in T i , Al, Mg and Fe is often observed within a given phenocryst, with grain rims most typically enriched in Ti and Fe and depleted in Mg and A1 relative to the cores The most Al,O,-depleted phlogopites (1-3 wt %) occur in the WKB, PRA (Kimberlite mine only) and H P suites (see Fig 25), whereas the MAP and LH suite phlogopites are relatively A1,03 rich (11-14 wt %) 'The SB and WKB lavas contain the most Ti0,-rich phlogopites (7-12 wt %and 5-1 1 wt % respectively) of all lamproite localities

L,amproite phlogopite compositions are dis., tinct from those in almost all igneous and metamorphic rocks (Fig 25) with the exception of some minette phlogopites (e g Bachinski & Simpson 1984; Velde, personal communication, 1985) The most notable exceptions are some kimberlites and their peridotite xenoliths, espe- cially the MARID-suite types (Dawson Sr Smith 1977; Erlank & Richard 197'7; Dawson 1980). Velde (personal communication, 1985) described phlogopites intermediate between phlogopite- annite-tetraferriphlogopite andferri-annite from a Jersey minette

Sanidine or rare microcline (and/or orthoclase) are theonly feldsparsibundin themore aluminous members of various lamproite suites (e g HOL., L,H, KAM, GSB, SB and MAP) Sanidine is restricted to the groundmass and is a 1ate.stage phase With the exception of the MAP rocks, lamproite sanidines are extremely K rich (Or.,,; Na,O=O-2 wt %; ('aO.:O 5 wt %)with anomalously high Fe203* (typically 0 555 wt %) and B a 0 (0 2-1 6 wt %)contents

'The extreme Fe-rich character of lamproite sanidines separates lamproites from nearly all other rock types; the sanidines from lampro.. phyres are usually in the range Or,,_,, and contain about 1 0 wt % Fe20, (Bachinski & Simpson 1984; Rock 1986) The absence of plagioclase in lamproites provides an effective means fbr distinguishing lamproites from other ultrapotassic-potassic rocks

L.eucite and analcime

Leucite is the only feldspathoid that occurs in lamproites Euhedral and anhedral leucrtes axe

- LAMPROITES 1971 - LAMPROPHYRES 1221 ----- KIMBERLITE XENOLITHS ,441

ALKALI BASALT XENOLlTHS (351 . . . . . . . ALKALI INTRUSlYES @ I

FIG. 24. Composltlons of amphiboles from IamDroltes and otller rock types: (a) A1,0, versus Mg number; (b) CaO veisus Mg number; (c) TiO, versus Mg number; (dl K,O versus Mg number. (See Table 10 and Appendix 2.) The bold curves enclose more than 90% of the data; the iight-face curves enclose more than 99% of the data.

I 6 2 S C Bergman

., .. .., ,

---..

' _ _ -- ,

.. . .- - . .

-. --1-----

30 40 M W 70 80 90 1 W ( b ) MQ number

-, LAMPROITES 1229)

- - LAMPROPHYRES 198) ALKALINE INTRUSIVES 132)

- - - - [ KIMBERLITE XENOLITHS 1193) K GROUNDMASS..PHEN-XENC 1186)

I c ) Mq number

FIG 25 Phlogopite compositions from lamproites compared with other rock types: (a) AI,O, versus Mg number as a function of the lamproite suite; (b) Al,O, and (c)TiO, versus Mg number for lamproites and other rock types (See'Table 10 and Appendix 2 )Bold and light.face curves as in Fig 24

Lamprottes and K

typically weakly anisotropic and twinned (e g WKB) or isotropic and twin free (e g LH) and are most often altered and pseudomorphed by secondary phases (e g sanidine, analcime, quartz and zeolites) Lamproite leucites are commonly non..stoichiometric with a marked excess of Si, Fe3+ and K Leucite Fe,O? contents are as high as 1-2 wt % These chemlcal features separate lamproite leucites from the leucites of other potassic-ultrapotassic rocks (e g R P and HM) which possess higher A1 and lower Si, K and Fe contents Analcime has been recognized in the SB, KAM, LH and MAP lamproite suites and most probably originates by the secondary r e placement of leucite, although this view is debatable Whereas Iamproites never display classic pseudoleucite textures (i e K-feldspar- nepheline intergrowths (Shand 1927)), other potassic-ultrapotassic rocks (e g HM, TAN and NSW) commonly contain classic pseudoleucite

Fe-Ti-CI-Mg-A1 oxides

A wide variety of oxide phases in the rhombo. hedral, cubic and orthorhombic series have been noted in lamproites Spinels (renru lato) fall into bur compositional groups and occur in rocks from WKB, LH, PRA, GSB, ARG, HP, HOL and MAP, among others : (a) Ti.poor Al-rich Mg chromites; (b) Ti-rich A1-Mg chromites; (c) Al.. poor 'Ti-Mg chromites; (d) Mg-Ti-magnetites Whereas some of these spinel types are commonly found in rocks other than lamproites, lamproite spinels are more Fe rich than kimberlite spinels

Oneous but are similar to those of other alkaline i, rocks (Haggerty 1976) Spinel zoning, when present, displays Cr-depleted and Fe3+-enriched rims relative to the cores (Mitchell 1985) L a m proite spinels tend to be more Mnrich than those from other alkalic mafic rocks (Table 10) Armalcolite has only been found in SB lavas (Velde 1975), but has been produced experimen- tally in studies on WKB rocks by Arima & Edgar (1983) (see below) Ilmenite with compositions relatively similar to those of other rock types has been noted in the GSB lavas (4 wt % MgO (Sheraton & England 1980)), at Sisco (COR) (Velde 1968), at Oscar's Plug (WKB) (S C Bergman, unpublished data), at Mount North (WKB) Wagner & Velde 1986a) and at Jumilla (MAP) (2 5-3 5 wt % MgO) (Mitchell 1985), but is generally absent Lamproite ilmenite MnO contents are higher, on the average, than those from compositionally related rock types (except alkali basalt xenolith ilmenites) (see 'Table 101, Anataseoccursin the aIteredBOB rocks(Mitchel1 1985) and rutile occurs in the CHE lamproites;

.-rzeh lgneozts rocks 163

Van Kooten (1980) and Kuehner (1980) d~scussed ferro-pseudobrook~tes from the CSN ultrapotas- sic rocks and LH lamproites respectively, but these phases are all most probably secondary

X-Fe-Ii-Ba oxides

The natural occurrence of the exotic phases priderite ((K,Ba)(Ti,Fe3+),0,,) and jeppeite ( ( K , B ~ I ) , ( T ~ , F ~ ~ ' ) ~ O , ~ ) is almost restiicted to lamproites Priderite has thus far been found in the WKB, COR, LH, KAM, HOL, SB and PRA lamproites, and will most probably be discovered in other suites as more detailed studies are performed Prider (1919) originally mistook pri. derite fbr rutile in the WKB rocks, and Cross (1897), Smithson (1959) and Johnston (1959) mistook it for rutile in L.H rocks; the more detailed study of the oxides in the WKB rocks by Norrish(l95l)and in theL.H rocks by Carmichael (1967) demonstrated its existence Apart fiom the priderite-bearing apatite glimmerites in India (Gupta et a1 1983), which are probably lam- proites, the only known extra-lamproite priderite occurrence (albeit Ba enriched relative to lam- proites) was reported by Zhuravleva et a1 (1978) in the olivinite--ijolite members of a carbonatite pluton in the Kola Peninsula, U S S R K Collerson (personal communication, 1984) iden- tifiedpridesite inAIL.minettes,Labrador NEmec (1985) described pxiderite from the K-richer members of Czechoslovakian minettes which may be lamproites. Jeppeite (Bagshaw et a1 1977; P ~ y c e et a1 1984) is apparently restricted to the Wolgidee Hills pluton (WKB) as well as the PRA priderite-bearing phlogopite pyroxenite xenoliths (Mitchell & L,ewis 198'3) Dubeau & Edgar (1985) presented experimental data on the stability of priderite as a function of pressure and temperature Muchmore workon thedistribution of priderite-jeppeite in lamproites and minettes is therefore required to understand its para- genesis

Wadeite

Wadeite (K,Zr,Si,O,,) is a hexagonal ring- silicate which was also originally discovered in the WKB lamproites (Prider 1939), where it occurs as rods up to l lnm long Carmichael (1967), Kuehner (1980), Kuehner et a1 (1981) and Henage (1972) additionally noted its presence in L.H and KAIM rocks B H. Scott-Smith (per- sonal communication, 1983) discovered wadeite in lamproites from PRA Tikhonenkov et a1 (1960) reported an extra-lamproite occurrence of

wadeite in nepheline-.feldspar veins of the Khi- bina alkaline massif, U S S R

Wadeite is compositionally related to dalyite (K,ZrSi,O,,) and other Zr silicates (zektzerite, sogdianite and darapiosite) which occur in rocks more enriched in SiO, than lamproites (e g hyperalkaline granites (Robins et a1 1983; Thi- baut et a1 1972)) Arima & Edgar (1980) studied the stability of pure wadeite and found that, by itself, it can occur under a wide range of upper- mantle to crustal P-I conditions

Shcher hakovite (noonkanbahite)

Shcherbakovite ((Na,K)(Ba,K)Ti,Si,,O,,) is an unusual phase that was discovered in the WKB wolgidites by Prider (1965) Eskova & Kazakova (1955) initially rzported its occurrence in alkalic pegmatites of rhe Khibina massif, U S.S R.

reported by ~ i a ~ c h e n k o i t a1 (1960) unforti-. nately, shcherbakovite has not received much attention since Prider's original work and only a limited amount of mineralogical data is available

Other phases

Important and common accessory phases of all lamproites include apatite and perovskite Sphene (mostly secondary) and zircon are rare accessory minerals Wagner & Velde (1986a) described rare roedderite-like phases (K, Fe, Mg silicates) in MAP and KAM larnproites Lam- proite secondary phases are widespread and include Sr-,rich barite, chlorite, heulandite, non- tronite, other zeolites, serpentine, carbonate minerals, quartz and rare albite As mentioned above, xenocrysts of a wide variety of phases, including diamonds and Cr-rich pyrope, can occur in lamproites However, lamproite pyropes are more enriched in MnO than are kimberlite and other pyropes, but are otherwise similar in chemistry

Mineralogy and mineral chemistry: sunrmarizing conrments

L.amproites contain a diverse suite of minerals, some of which are restricted to lamproites The diagnostic mineral assemblages (i e containing phlogopite, K..richterite, priderite, shcherhakov-' ite and wadeite)and uniquemineralcompositions (K-rich, Ca- and Al-poor amphiboles, Na- and Al.poor diopsides; Ti-rich, Al-poor phlogopites; Ba- and Fe-rich sanidines; Fe-, K- and Si-rich leucites; the mafic minerals largely' possessing

'ergmnn

primitive Mg numbeis in the range 85-93, although more differentiated phases can occur) shown by lamproites reflect their peralkaline and primitive compositions and provide eff'ective means for distinguishing lamproites from other alkalic mafic-ultramafic magmatic rocks As discussed at length by Mitchell (1985), the zoning characteristics displayed by lamproite phases place important constraints on both the crystalli- zation history of individual magmas and the petrogenetic relationships between several lam- proite magmas Interestingly, the elevated MnO contents of lamproite amphiboles, ilmenites, spinels and garnets are in marked contrast with the MnO-depleted character of the lamproite whole-rock samples (0 10 wt % (Table 5)) com- pared with kimberlites, alkali basaits etc

Experimental studies on K-rich rocks and thei-r minerals

Reviews of experimental studies dealing with K - rich rocks and their minerals have been given by Gupta & Yagi (1980) and (>ittins (1979) There- ibre important and more recent papers on the subject are summarized in this section

Natur a1 lamproites

The high.?-7 phase relations of Iamproite rock compositions have been determined by Barton (1976), Barton & Hamilton (1978, 1979, 1982) and Arima & Edgar (1983) Barton & Hamilton studied orendites, wyomingites and madupites from the LH and found that only the orendites and wyomingites could equilibrate with a garnet Iherzolite assemblage at P > 2 6 kh and PHZO= P,,,,, Madupites probably represent partial melts of phlogopite-pyroxenite or phlogopite-olivine- pyroxenite assemblages (Barton & Hamilton 1979) Barton & Hamilton's experiments indicate that the dominant liquidus or near-liquidus phases are leucite, olivine, orthopyroxene, cline.. pyroxene and garnet at P < l O kb They also concluded that the peralkalinity of these ultrapo tassic magmas could reflect either primary source rock compositions or the selective melting of phlogopitet pyroxene They postulated that the association of low-SiO, madupites with high- SiO, orendites at LH results fiom variations in H,O and CO, and local mineral assemblages in the upper mantle source region It should be noted that A Edgar (personal communication, 1985) questions the validity of the phase relation ships determined by Barton because of Fe partitioning in platinum capsules Sobolev et a1

Larnproztes and K

(1975) studied the low-P near-liquidus phase equilibria of a L.H wyomingite and found that diopside is the sole liquidus phase at temperatures around 1320°C and P= 1 b despite the fact that phlogopite phenocrysts are cornmon and that the 1 b solidus temperature is about 1000°C

Arima & Edgar (1983) studied the hydrous (f C0,)liquidus and sub-liquidus phase relations of a wolgidite (from the WKB, Mount North) to 40 kb They fbuitd that olivine (at P i 15-24 kb) and orthopyroxene (P> 15-24 kb) occur on the liquidus; phlogopite, rutile, clinopyroxene, ar- malcolite and priderite follow at lower P and 7 Rutile reacts with phlogopite arid liquid to produce priderite at P < IS kb and T < 10IO°C, and armalcolite reacts to form priderite at 7 < 1010°C and P < 15 kb ; rutile is the high-pressure phase and armalcolite is the high-temperature phase 'These phases (priderite, armalcolite and rutile) were only found in runs containing added H 2 0 (13 wt %) and were absent from runs with low H 2 0 contents (3 wt %) Their results indicate that wolgidite magma most probably represents the partial melt of a source mantle containing phlogopite, rutile, olivine and orthopyroxene i t is unlikely that a wolgidite-composition melt would be derived from the partial melting of a simplegarnet- or spinel~bearinglherzolitemantle, in contrast with the derivation of typical alkali basalts from such a mantle

Other ultr apotassic rock compositions

Edgar et a1 (1976, 1979), Edgar (19'791, Edgar & Arima (1983), Ryabchikov & Green (1978), Arima & Edgar (198.3) and Edgar & Condliffe (1978) investigatedthephasebehaviour of'several TAN rocks (biotite ugandite, biotite mafurite and katungite) in the presence of H 2 0 + C 0 2 to 40 kb They found that these melts never equili- brate with an orthopyroxene- or garnet-bearing assemblage and that only diopside, olivine, ilmenite and phlogopite occur on the liquidus, even at high pressule These three magmas cannot be related to each other by fractionation alone or by partial melting of a single mantle source region The three magma compositions could be derived by partial melting, at various depths, of clinopyroxenite or peridotite sources with varying degrees of enrichment in K where low H,0/C02 ratios produce low enrichments in K Their experimental findings favour metaso- matism of a peridotitic mantle source as a prerequisite for theproductionofK-richmagmas. Ryabchikov & Green (1978), how eve^, concluded that biotite mafurite, olivine leucitite and ugan dite liquids could be produced by the partial melting in the presence of H 2 0 and CO, of a

lherzolite source mantle locally enriched in phiogopite Phlogopite occurs on the liquidus at high H 2 0 / C 0 2 ratios (Xco,=O-0 25), but be. comes unstable at higher ~ 6 , contents (Xco, > 0 25)

Cundari & O'Hara (1976) studied the phase equilibria of a leucitite from NSW under anhy- drous conditions to 40 kb and determined that garnet did not exist with enstatite above 35 kb, indicating that orthopyroxene did not occur in an anhydrous source pe1,idotite.

Thompson (1977) experimentally studied a clinopyroxene leucitite from the RP and found that the phenocryst assemblage could be dupli- cated at 14 kb and 1260°C, indicating a mantle derivation He postulated that the experimental data were consistent with the view that the apparent crustal contamination (suggested by SI- 0 isotope data) was due to the partial fusion of subductedocean-floor sediments within theupper mantle Other experimental work on potassic and ultrapotassic rocks includes that of Dolfi et a1 (1976), Lloyd et a1 (1985), and Esperanca & Holloway (1985)

Compositions in the system Na,O-K,O-MgO- Al2O3SiO,-HzO-COZ

Schairer & Bowen (1938) studied the anhydrous system KA1Si206-CaMgSi206-SiO, at 1 atm and established the phase equilibria pertinent to Fe-free K-rich alkaline magmas. They found an extremely large leucite field in the leucite- diopside-silica ternary system However, more recent work on the hydrous analogue of this system (Ruddock & Hamilton 1978a) demon- strates that the ieucite field is extremely com- pressed, which explains the general absence of leucite in minettes L.uth (1967) determined the phase equilibria in the system Mg2Si0,- KAISi0,-Si0,-H20

Bravo & O'Hara (1975) studied the partial melting of a synthetic phiogopite-bearing garnet and spinel lherzolite (C02 free) and found that partial melts of these solids at 15 and 30 kb had extremely low K 2 0 contents (1-4 wt %)and were quartz- and/or hypersthene-noinlative These liquids share an SO2-rich compositional feature with lamproites, although they are relatively depleted in K 2 0 relative to lamproites Modreski &Boettcher (1972,1973)investigated the stability of phlogopite in a model system and found that it is unstable under oceanic geothermal conditions of P > 2 5 kb but may persist in sub-continental geothermal conditions to P > 50 kb

Wendlandt (1977a, b) and Wendlandt & Eggler (1980a, b, c) investigated the stability andmelting behaviour of sanidine and phlogopite in olivine-

bearing assemblages They found that sanidine t. forsterite breaks down to kalsilitetenstatite along a P-7 locus including 20 kb at 1000°C and 30 kb at l30OoC, indicating that the latter assemblage will be stable along most geotherms (Wendlandt & Eggler 1980~) The melting behav- iour of phlogopite in peridotite was found to be controlled by the equilibrium miner a1 assemblage as well as by the composition of the volatile phase ( H 2 0 verslis C 0 2 ) At P i 1 4 kb the liquid compositions were quartz or ensiatite normative, but became leucite to kalsilite normative at higher pressures in the presence of C 0 , + H 2 0 vapour At pressures above 30 kb in the presence of magnesite, phlogopite peridotite melts to produce carbonatitic liquids which become pro- gressively enriched in K 2 0 and SiO, as pressure increases Phlogopite is not stable in a peridotite assemblage above 50 kb

Ryabchikov & Boettcher (1981) investigated the solubility of K in an aqueous fluid in equilibrium with phlogopite-pyrope-f'orsterite gels at 10-30 kb and 1050-1 100°C and found that water is capable of dissolving 4-25% K,O and that solute K20/A120, ratios are close to unity,

Ruddock & Hamilton (19'78a) experimentally studied the system leucite-diopside-quartz-H20 to 4 kb and confirmed that, under hydrous conditions, diopside and phlogopite will be the first two liquidus phases followed by sanidine and quartz 'Thisstudy nicely explains the petrography of minettes and other lamprophyres (however, see Rock (1984, Fig 8) for an alternative interpretation) Ruddock & Hamilton (1978b) determined the stability of carbonate in an ultrapotassic mafic assemblage and found that a minette composition liquid is saturated in olivine, garnet, orthopyroxene and clinopyroxene at pres- sures above 15-20 kb and is saturated in carbonate at pressures above 20-10 kb

Schneider (1982) and Schneider & Eggler (1984) determined the high P-7 (15-20 kb and 750-1100°C) solubility of major-element oxides in H,O and H20-CO, Ruids in equilibrium with jadeite-, amphibole- and phlogopite-peridotite and several individual mine~als They fbund that the fluid's solute contents wele in the range 0 5- 18 wt % and increased with decreasing CO? content H 2 0 or H 2 0 + C 0 2 fluids in equilibrium with phlogopite-peridotite were found to be peraluminous whereas H,O + C 0 2 fluids in equi- librium with amphibole- or jadeite-peridotite ranged from mildly peraluminous to strongly peralkaline in their solute compositions Solute K/Naratios were found to be controlled by H,O/ CO, as well as by P , 7 and the bulk composition of the solid, whereby K/Na increases with increasing C 0 , / H 2 0 ratio of the Ruid

Pelr ogenesis

A wide variety of models have been advocated for the evolution of K-rich rocks; the reader is refe~red to previous reviews by Bell & Powell (1969), Sahama (1974) and Gupta & Yagi (1980) Most hypotheses can be placed in one of three broad groups

1 Partial melting of mantle material that was metasomatically (or otherwise, e g by plutonism) enriched in phlogopite and other LIL-element- enriched minor phases (e g apatite, zircon, sphene etc ); the melt may be subject to variable amounts of fractionation but does not undergo substantial assimilation of crustal mate~ial (Waters 1955; Yagi & Matsumoto 1966; Kay & Gast 1973; Boettcher et a1 1975; Beswick 1976; Guptaetal 1976; Van Kooten 1980) 2 Assimilation of continental crustal material by 'nor.ma1' mantle-derived alkali-basaltic, car.. bonatitic or alkali-ultcamafic melts (Daly 1910, 1933; Shand 1931; Rittman 1931; Larsen 1940; Williams 1936; Holmes 1950; Powell & Bell 1970; Taylor & Turi 1976; Turi & Taylor 1976; Taylor el a1 1984) 3 Evolution involving processes such as zone refining, fractional resotption, gaseous transport etc in otherwise typical mantlederived melts (Bowen 1928; Saether 1950; Kennedy 1955; Harris 1957; Prider 1960; Marinelli & Mittem- pergher 1966; Fuster et a1 1967; Kogarko 1980; Kogarko et a1 1968; Kushiro & Aoki 1968; Harris & Middlemost 1969; Stewart 1979; Wones 1979; Ryabchikov et a1 1982)

Sahama (1974) observed that researchers tend to desire hypotheses that attempt to explain the petrogenesis of K:rich rocks in general; however, the geochemical distinctions between lamproites and kamafugitic as well as other K-rich rocks do not permit such a luxury. 'The tectonic-geological and geochemical distinctions between lam- proites, kamafugites, shoshonites and other K- rich rocks clearly support this view

The last statement in Sahama's (1974) review of K-rich rocks speculates on a relationship between kimberlites, lamproites and kamafug- ites Gupta & Yagi (1980) additionally recogrlized the importance of this speculation The last 10 years have witnessed major discoveries of dia- mondiferous lamproites and other developments which make this speculation a reasonable, if not undeniable, view Although kimberlites and olivine lamproites evolve differently, they possess many similarities which have led several workers to suggest a petrogenetic model for lamproites

whereby kimberlite magma is differentiated to produce a more potassic SiO,-rich lanlproite-. kamafugite magma (Hoimes 1932; Wade & Prider 1940; Scott 1981)

Although more data are required to establish an unambiguous petrogenetic picture for lam- proites, the data now available make it possible to constrain their petrogenesis to a much greater degiee than was possible as little as 10 years ago. In addition, many aspects of the petrogenesis of lamproites have important implications for a variety of aspects ofmantle evolution and magma genesis

L.amproites are mantle-derived melts and do not simply result from the melting of recycled continental crust 'This is supported by (a) the presence of diamonds in olivine lamproites, (b) the presence of mantle-derived peridotite xenol- iths (albeit much rarer than their abundance in alkali basalts and kimberlites) in leucite, phlogo- pite and olivine lamproites, (c) a primitive (Mg numbei 74 + 9) mafic-ultramafic major-element composition, (d) an enrichment in the refractory trace elements Co, Cr, Ni and Sc, and (e) the mantle-type pressures and teniperatures (P= 20- 30 kb and T= 1100-1300°C) calculated by per-. forming thermodynamic isoactivity calculations (Nicholls & Carmichael 1972; Carmichael et a1 1974, 1977; Barton & Wood 1976) in which lamproite magmas are equilibrated with various source-mantle assemblages

In contrast with being enriched in LIL ele- ments, lamproite magmas possess major-element compositional features typical of partial melts of a refractory (i e Mg number, 88-92, diopside- depleted, harzburgite?) mantle: they are depleted in the incompatible elements Na, A1 and Ca compared with alkali basalts and other primary melts considered to represent low degrees (less than 10%) of partial melting of a lherzolite.. composition mantle A depleted diopside-poor source is further supported by the high.?-3 experimental studies on lamproite compositions which suggest a non-lherzolite mantle source for Iamproite magmas (see above) and also by the characteristically refractory harzburgite and dun- ite xenolith population that occurs rarely in several lamproite suites (e g WKB, LH, MAP) However, there are other ways of interpreting this depletion in certain major elements Lam- proites are phlogopite-rich rocks and many whole-rock analyses of lamproites approach but are more calcic and siliceous than the bulk compositionofphlogopite Thereforeitispossible that lamproites represent the selective hactional fusion of mantle phlogopite and other LIL- element enriched phases (e g apatite, zircon etc ) diluted by small amounts of peridotite compo-

'rlch zgneous rocks 167

nents (clinopyroxene, orthopyroxene and oli- vine). Since phlogopite is severely depleted in Na and Ca and moderately depleted in A1 compared with basaltic melts, this model nicely explains the bulk chemistry of lamproites It is further supported by the fact that phlogopite is not expected to survive extensive amounts of partial melting, most of it being consumed at extreme11 low degrees of melting

The ultrapotassic but variable K/Na ratios of lamproites can be interpreted in a number of ways K can be enriched relative to Na as a result of (a) source-mantle characteristics, i e precipi- tation of phlogopite (Na absent) via metasoma-, tism in a Na-poor refractory peridotite, (b) fractionation of high K/Na phases (e g phlogo- pite, leucite) and (c) selective volatile-phase transfer of K relative to Na The experimental work by Schneider& Eggler (1984) andschneider (1982) contributes important data with which to judge the effectiveness of the latter process, i e K/Na in the fluid varies with C 0 2 / H 2 0 How- ever, much more work on it is required to understand vapour-phase transfer of alkalis p r o p erly Since this feature is a local a s well as a general feature of lamproites, it most probably results from a combination of all these processes (see discussion in Sahama (1974, p 106) )

Like alkali basalts and lamprophyres, the volatile budgets of leucite-lamproite and phlo- gopite-lamproite magmas are water-dominated (relative to CO,), whereas those of' kimberlites (and olivine-lamproites) possess higher and sub- equal H?O and CO, contents The H 2 0 contents of kiniberlites indicated in Tables 4 and 5 are maximum values for the magmas, and the true values are most probably a factor of 2 lower owing to the ubiquitous and often secondary serpentinization that characterizes kimbe~lite groundmass and xenocrysts As mentioned above this H,O-rich character provides an explanation for the sherbet-glass shape of' Iamproite pipes. It is also consistent with the SiO,-rich and variable composition of lamproites Experimental work by Mysen & Boettcher (1975a, b) and Eggler (1977) has shown that partial melting of a peridotite with a high H,O/(CO,+H,O) ratio will produce a relatively SO2-rich melt, elimina- ting the need to invoke fractionation of low-SiO, mafic minerals to produce SO2-rich lamproites Slight variations in the source H?O/(CO, +H,O) ratio would produce variations in the SiO, contents of partial melts (e g Bachinski & Scott 1979) Therefore, whereas kimberlites and alkali olivine basalts are SiOz undersaturated and are most probably derived from a mantle source with a low H,O/(CO, + H,O) ratio, lamproite soulces represent the complementary volatile situation

(high H,0/(C02 + H,O)) in addition to other contrasts, i e L.IL-element enrichments

Of all the alkaline rocks, lamproites are consistently among the most enriched in LIL.. elements They are also characterized by enrich- ments in higher-series elements relative to lower- series elements in the same group (e g lower K/ R b and Sr/Ba) compared with virtually all other rock types It is now clear that this feature is a mantle pheriomenon and does not require crustal contamination for its explanation 'The highly variable concentrations of LIL-elements in l a m proites is easily explained by a heterogeneous distribution of' L1L.-element-enriched phases in the source mantle in addition to volatile-phase transfer processes acting during magma ascent These minerals, most importantly phlogopite but also including other L,IL.element.enriched phases such as apatite, monazite, sphene, rutile and zircon, originated from the process of mantle metasomatism, most recently reviewed by Bailey (1982) and Dawson (1984) These phases could be precipitated or otherwise produced from any number of sources, including (a) fluids ascending fiom a downgoing slab which hybridize the overlying mantle wedge, (b) fluids emanating from an ascending plume, (c) 'background' deep- mantle fluids ascending throughout the upper mantle and (d) silicate melts of variable origins As mentioned above, this metasomatism must have been fairly old (10-10' Ma) to generate the 87Sr/86S~ and l4'Nd/'*%d ratios of lamproites The age of this lamproite-source metasomatism contrasts with that suggested for the source regions of alkali basalts and related melts Since II,O is suggested as the most important 'lam- proite volatile', the mantle metasomatism asso- ciated with lamproite source regions may be distinct from that associated with alkali basalts (C0,-'rich?)

If we accept the view that olivine lamproites and leucite lamproites (or phlogopite lamproites) form a cognate petrolog,ical continuum, a view that is supported by the tlme-space--composition relationships present within the WKB and PRA suites, several implications arise The composi- tional variations in these suites indicate the existence of differentiation processes more com- plex and less understood than simple crystal fractionation Also, the preservationof diamonds within the WKB and PRA suite diatremes indicates that these magmas explosively ascend to thesu~facefromdepthsofgreater than 150 km, i e within the diamond stability field in the upper mantle because lamproite melts, which are extremely hydrous, would otherwise oxidize the diamonds Although this feature is shared by kimberlites, many lamproite diamonds display a

'ergrinn

greater degree of graphitization and rounding than those from kimberlites; these ieatures may indicate that lamproite magmas ascend more slowly than kimberlites Much more work on the stability of diamond in lamproite magmas is required to acquire a better understanding of the ascent characteristics of lamproites

Another implication resulting fiom the mantle derivation of lamproites involves the radiogenic isotope systems Sm-Nd and Rb-Sr Some re- searchers have recently interpreted the isotopic data of K.rich rocks as indicating the operation of continental crust contamination (e g TAN (Vollmer & Norry 1983b)) or the mixing of a depleted mantle component (similar to MORB: E ~ ~ = t 10and&,, = - 40) withanenrichedmantie component (zNd = - 16 and zs, = + 240, e g WKB (McCulloch et a1 1983a, b)) However, the isotopic data can also be interpreted in the context of a single-mantle reservoir that is heterogeneous but enriched in its Rb/Sr and Nd/ Sm ratios relative to the bulk Earth The heterogeneities could be related to partial melting or plutonic processes Small differences in these ratios can produce the time-integrated range in '"3Nd/'44Nd and 87Sr/86Sr ratios observed for lamproites Regardless of the specific model used to interpret the isotopic data (as all are non- unique), an enriched mantle source is required by all This 'enriched' source is also represented by Group I1 kimberlites (Smith 1983a, h) and the diopsides from kimberlite xenoliths (Menzies & Mur.thy 1980a, b ; Basu & Tatsunloto 1980) However, the major-.element chemistry of lam: proites is characterized by a depletion in some of the major elements that. are the first to enter partial melts (Ca, A1 and Na) and an enrichment in refractory elements (Mg and Ni) so that the source probably experienced a partial-melting event prior to the enrichment in Nd/Sm and Rb/ Sr (see above) When this is viewed in the light of the Pb isotope data obtained by Fraser et a1 (1985) and Nelson er a1 (1986) (see above), it is seen that lamproite mantle sources must have been subjected to depletion events followed by enrichment events a long time ago ((1 -3) x 10' Ma) This model has interesting implications for Earth history because not only does it suggest the enriched complement to the depleted mantle source represented by MORB and nearly all alkali basalts (except suites such as Kerguelen and Tristan da Cunha), it also supports the existence of Precambrian partial-melting episodes in the mantle and suggests a three-stage model of pet~ogenesis If the more recent lamproite suites that occur overlying fossil Benioff zones indicate the general tectonic environment of lamproites, then it is possible that lamproites represent

Larnproztes and K,

partial melts of sub-continental lithosphere- asthenosphere that was (a) initially depleted by the formation of MORB at a spreading centre, (b) moved beneath a continent and (c) later hybridizedperhaps by fluids andmelts emanating from a downgoing slab All this must have taken place sufficiently long ago to permit the develop- ment of time-integrated high 87Sr/86S~ and low "3Nd/'4"Nd ratios The most recent melting event that led :o the surface emplacement of Iamproite magmas could be triggered01 enhanced by a number of mechanisms, including transient hot.spots (randomly contacting the unique l a m proite-source hybridized mantle; unlike ocean island chains, however, lamproites do not gener.. ally form time-space-related linear trends), the build-up of radiogenic heat (due to sources enriched in K, Th and U) and the tectonic conditions of the overlying crust (involving deep fractures) It should be noted that variations of this threestage model of depletion-enrichment- melting have been suggested by various workers (Best 1975; Beswick 1976; Thompsonetali984)

When the lamproite seniu rtricto and other ultrapotassic rock localities are plotted on a map with the continents in the positions of' 180-200 Ma ago (see Fig 26), a zonal pattern of the distribution of these K-rich rocks emerges Two broad belts are evident: one belt 3000 km long includes the Indian, W Australian and Antarctic occurrences, and the other more diffuse belt includes the N American, European and W African localities Since themantle source regions

-r zch zgneous rocks 169

of lamproites are evidently very old, thispre-drift zonation is perhapsexpectedandnot only permits the possible prediction of other lamproite locali- ties but also has important implications for mantle evolution Is it possible that the southern hemisphere lamproite belt (representing 1 2 x lo3 Ma of magmatic activity) delineates a Precambrian (Archaean?) zone of recycling of crustal material (fossil Benioff zone)?

While much speculation has filtered into this discussion, it is hoped that a coherent picture of lamproite petrogenesis has emerged The lam: p~oi te revolution is only in its infancy and future studies of these exotic rocks will surely clarify many ofthe issues only briefly discussed here

Kimberlite-larnpn oite r elationships

Dawson (1987) summarizes the similarities in geochemistry and mineralogy between olivine lamproites and the more micaceous kimberlites (including those in Group I1 of Smith (19831, b)) and suggests that olivine lamproites may, in fact, be members of the Group I1 kimberlites Smith (1983b) demonstrated Nd-Sr-Pb isotopic similar-. ity between Group I1 kimberlites and olivine lamproites from PRA and WKB and suggested further that they are one and the same, a view that is additionally held by the present author Smith (1983b) also suggested that lamproites (as well as Group I1 kimberlites) were derived by the partial melting of sub-continental lithosphere,

L A M P R O I T E S 8 U L T R A P O T A S S I C ROCKS

A K I M B E R L I T E S

.-

t +

\

*

FIG 26 Distribution of lamproites ultrapotassic rocks and kimberiites on a map showing a reconstruction of the continents 150-200 Ma ago (Owen 198.3) Lamproites fall along two btoad belts

whereas Group I kimberlites were derived by the partial melting of sub-continental lithosphere or underlying asthenosphere The fact that MARID-suite xenoliths occur in kimberiites, indicating 1amproite.type plutonic-metasomatic processes in sub-continental lithosphere encoun. tered by the host ascending kimberlite magmas, is consistent with both lamproite and kimberlite melts existing in similar areas in the upper mantle

Relationships between lamproites and MARID and other micabrich xenoliths

The similarity between the geochemistry and mineralogy of lamproites on the one hand and the MARID glimmerite and PKP (amphibole- peridotite) suitesof'xenoliths found in kimberlites on the other suggests some type of relationship MARID xenoliths, which aze also known as 'mantle pegmatites' consist of mica, amphibole, rutile, ilmenite and diopside (Dawson & Smith 1977); in addition, compositionally.similar phases (Ti-mica, K-richterite) are observed as metasomatic alteration products of many peri-, dotite xenoliths from kimberlites (Erlank 1970, 1977; Erlank& Rickasd 1977; Erlanketal 1982; Jones & Smith 1985) Haggerty (1983) and Haggerty et a1 (1983) discussed K-Ba--Cs titan- ates from metasomatized peridotite xenoliths from S Africa; these phases are not unlike the priderite-jeppeite phases from lamproites Jones et a1 (1985) presented isotopic data for xenoliths from Kimbesley, S Africa, which indicated that glimmerite xenoliths weIe disrupted pegmatitic segregations of' Group I kimberlites (terminology of Smith (1983a, b)), whereas MARID and PKP xenoliths formed by magmatic-metasomatic processes involving both Group I and Group I1 components However, trace-element and is* topic studies on metasomatized peridotite and MARID xenoliths from the Bultf'ontein kimber- lite mine, Kimberley, S Africa (Kramers et a1 1981) have demonstrated that the Sr-Nd-Pb isotopic featuies are consistent with mixing of a metasomatic fluid from a slightly depleted mantle source with mantle material showing a time- integrated enrichment in incompatible elements Nevertheless, the dominant (albeit extremely rare) amphibole in kimberlites or in the replace- ment zones in their included-mantle xenoliths is the K-rich richterite (slightly depleted in Ti relative to lamproite K-richterites) which is the characteristic (and nearly ubiquitous) amphibole in Iamproites 'The subtle compositional diff'er-

ences between K-.richterites of lamproite, MARID xenoliths and metasomatized peridotite xenoliths can be explained by a variable buffering capacity ofthe host mantleperidotite which may modify the original amphibole composition The presence of K-richterite, combined with the Ti- and phlogopite-rich nature of MARID suite xenoliths, further suggests that 1amproite.like fluids were the agents of patent metasomatism of kimberlite xenoliths; lamproite melts may be responsible for the precipitation of MARID xenoliths However, much remains to be explored in the MARID and metasomatized xenoliths before the extent of this genetic relationship is fully realized Interestingly, the nature of' me ta somatic phases (mica and amphibole) in lherzolite and harzburgite xenoliths from alkali basalts (higher Al, and kaersutite or pargasite rather than richterite (Boettcher & O'Neil 1980; Men.. zies & Murthy 1980b)) substantiates a distinct nature to the mantle source regions of MARID- suite xenoliths and metasomatized alkali basalt xenoliths

Conclusions

Lamproites are recognized as a coherent but variable and exotic petrographic and chemical group of K-rich igneous rocks which border on and share certain petrogenetic aspects with the alkali basalt, kimberlite, lamprophyre and other K..rich rock clans Lamproites should not be included in the lamprophyre clan Lamproites can be effectively distinguished from these other rock types on the basis of mineralogy, mineral chemistry and wholerock major, traceelement and isotope chemistry L.amproites are unparal., leled by other rock types with respect to their compositions Known lamproites occur in 21 suites on six continents Lamproites occur closer to the margins of continents whereas kimberlites are most abundant nearer the ciaton cores; lamproites oiten intrude crust that overlies fossil Benioff zones Lamproites are partial melts of' a metasomatized (i e phlogopite., apatite.bearing) but depleted (in Na, Al, Ca) source-mantle peridotite (harzburgite) A threestage model (depletion-enrichment-melting), at least, is re. quired to explain the evolution of the source regions of lamproite magmas Lamproites diffes- entiate by piocesses including crystal fractiona- tion, fractional resorption and volatile-phase transfer, among others

ACKNOWLEDGMENIS : This ~esearch was supported by the Anaconda

Minerals Company, a division of the Atlantic Richfield

L.arnproltes and K-rzch zgneous rocks 1'7 I

Corporation, in conjunction with their diamond explo- ration programme in the U S and Kalimantan I thank R W Knostman, I. Gemuts and L G Krol lor their continued support Prepiints supplied by R Mitchell, B Scott-Smith, D Colchester, J V Smith, P H Nixon, P Gregory, D Velde, R Vollrner, C Hawkes- worth and M Menzies are gratefully appreciated These workers, as well as L G Krol, N R Baker, M Skinner, D Velde, S Bachinski, P Berendson, M Bickford, K Colleison, F Albarede, K Fraser and F Dodge, participated in many fruitful discussions which

PRA

(GAL)

Bolivar 1977; Gogineni el a1 19'78; Williams 1891; Scott-Smith & Skinner 1984a, b ; Bergman, unpublished data Matson 1960; Velde 1975; Bergman, unpublished data Hawkins 1976 Van Kooten 1980 Dodge & Moore 1981 Ross 1926b Allen er al. 19'75

served to improve the content of this report. Two days ( H M ) weed & pirsson 1896; pirsson 1905; with D and B Velde in Ayron proved enlightening. Pat Bickford generously supplied unpublished mineral

Osborne & Roberts 1931; Wolff 1938;

chemical data on the Hills Pond rocks, Peter Nixon Hurlbut & Griggs 1919; Buie 1941;

provided samples of the Mnrcia-Almeiia larnproites, Tappe 1966; Witkind 1969, 1973; Pieter Berendsen provided samples of the Hills Pond Woods 1975; Bergman, unpublished Iamoroites and B Scotc-Smith suoolied samoles of the data . . Holsteinsborg lamproites I thank R Baker, D Dunn, J Crann and W Turner for logistical support and assistance in the field in the U S A,, Indonesia and Australia S Self greatly assisted in the interpretation of the piperno and other pyroclastic rock textures L Noodles and Maggie clarified many confusing concepts An exceedingly constructive review by Sharon Bachin.. ski was invaluable; D Velde, L Krol and J G Fitton additionally provided useful criticisms on an earlier draft I thank J G Fitton and B G J . Upton for only requiring a 25% reduction in the length of the original manuscript. I thank G W DeArmond, G. McEntire, D Schraeder, I Auvermann and I Martinez for peribrming many arduous literature searches and for obtaining many 01 the obscure references cited in the text I thank 1. Toney and D J Henry ior much invaluable help in the microprobe work The rock and mineral chemistry data bases were compiled with the able assistance of V Mount, S R Yang, F Stiff and E Kinsel to whom I express sincere thanks The manu- script was typed by S Epperson and the graphics were professionally produced by N Murray

APPENDIX 1

Sources of whole-rock major and trace-element analytical data in Tables 4-7 and associated figs 20-22

EVE) L~bby 1975 HOL Scott 1979 H P Flanks et a1 1971, Meri~llet a1 1977 KAM Best eta1 1968, Bergman, unpublished

data L.H Carmichael 1967; Kuehner 1980,

Kuehner et a1 1981; Schultz & Cross 1912; Yagi & ~Matsumoto 1966; Berg- man, unpublished data

(KNX) Bastin 1906 (NHB) Williams 1936; L.ewis 1973; Schmitt el

a1 1974; Rogers et a1 1982 (SEW) Miller 1972 (SFC) Temoleman-Kluitt 1969 (TB) ' Cros's 1906 (CHIN) Arculus & Smlth 1979, Schulze &

Helmstaedt 1979

Australia

WKB Wade & Proder 1940; Prides 1960, 1982; Atkinson et a1 1984a; Jaques el a1 1984b; Nixon et a1 1984; Bergman, unpublished data

ARG Atkinson er a1 1984a (NSW) Cundari 197:3

Europe

MAP Osann 1906; Washington 1917; Parga Pondal 1935; Fuster & Pedro 1951; Borley 1967; Fuster et a1 1967; Nixon et a1 1984: Venturelli el a1 1984a

NWI Dal P ~ a z et a1 1979, Venturelli el a1 1984b

PEN Hall 1982 HLM T~dmarsh 1932, Knill 1969 COR Velde 1967 (TUSC) Gallo 1984 (SUNN) Furnes el a1 1982 (BOH) NEmec 1972 (LAC) Duda & Schminke 1978

Africa

BOB Bardet 1973 PPS (Swaitiuggens only) Skinner & Scott

1979, Bergman, unpublished data

('IAN) Holmes & Harwood 1937; Holmes leucite, A analcime, J priderite and jeppeite, A 1950; Higazy 1954; Sahama 1974; amphibole, I ilmenite, G garnet (suite abbrevia- Mitchell &Bell 1976 tions are as given in appendix 3)

(AZZ) Vila et a1 1974 ARG Atkinson et a1 1984a (G, H, C); Scott..Smith & Skinner 1984b (P)

Anta~ctica C.? S B Sheraton & Cundari 1980 (I, S, H,

GSB Sheraton & Cundari 1980 0, p , C)

MBAY, HOL Scott 1981 (A, S, 0, P, C)

PP Sheraton & England 1980 HP Merrill et a1 1977 (A, P, C); P

Bickford, personal communication 1984 (A, C, P, S); Mitchell 1985 (P,

Asia and Indonesia

COC L.acroix 193.3a, b CHE Bergman & Baker 1981 GDW Sarkar eta1 1980; Guptaetal 1983 (BAL) Kostyuk 1983 (KAJ) Brouwer 1909 Abbreviations are given in Tables 2 and 3 and in the text

Average compositions

The major- and trace-element data for lamproite senru stritto are cited above; the major-element data fbr lamprophyres, kimberlites and 'alkali basalts were compiled on a computerized data bank that is a combination of the Mutchler et a1 (1973) PETROS data bank and a literature compilation by Bergman (File DIROC) Individ- ual r.eferences can be obtained by writing to Bergman Traceelement data for kimberlites and alkali basalts are taken from Wedepohl & Muramatsu (1979) and data forlamprophyres are taken from Rock (1954, 1986) The estimated composition oi'the primitive mantle comes from Taylor & McL.ennan (1981) or Mason (19'79)

APPENDIX 2

Sources of mineral chemical data of Table 10 and Figs 23-25

The mineral chemical data used in these figures and table have been compiled in a computerized data file DIMIC that comprises over 137,000 analyses of phases from kimberlites, lampro- phyres, lamproites, alkali basalts and their in- cluded xenoliths and megacrysts (S C Bergman, unpublished) Since it is unreasonable to tabulate all the data sources here, a copy of the sources can be obtained by writing to Bergman Only sources containing lamproite mineral chemical data will be summarized The abbreviations are as follows : P phlogopite, O olivine, C clinopyrox- ene, H orthopyroxene, S spinel, F sanidine, 1.

S) L.H Carmichael 1967 (A, S, 0, P, (1, J,

F, L); Barton 1979 (L, F, C, P); Kuehner 1980 (A,S, 0 , P, C);Barton & van Bergen 1981 (H, 0, P, C); Kuehner et a1 1981 (A, S, 0, P, C); Mitchell 1985 (S, J)

MAP Borley 1967 (P, C); Carmichael1967 (P, F, 0 , C, A); Fustor et a1 1967 (P); Lopez Ruiz & Rodriguez Badi- ola 1980 (A, 0 , P, C); Venturelli et a1 1984a (A, H, S, P, P, C); Mitchell 1985 (P, F,I)

MBAY, P P Sheraton & England 1980 (A, P, I, F)

PEN Hall 1982 (A, P, F) PRA Lewis et a1 1976 (G, S, 0 , P, C);

Gogineni et a1 1978 (A, G, S, 0 , P, C) ; Mitchell & Lewis 1981 (A, C, P, J): Scott-Smith & Skinner 1984a, c (A, S, 0 , P, C); Mitchell 1985 (1)

SB Velde 1975 (A, S, P, C); Mitchell 1985 (P, 0, N, F, S), Henry & Bergman, unpublished data (A, P, c , 0 , S)

WKB Carmichael 1967 (C, P, A, F, L, J); Mitchell 1981 (P); Mitchell & Lewis 1983 (A, P, C): Atkinsonetal 1984a (G, H, S, C); Jaques et a1 1984a, b (A, G, H, S, 0, C); Pryce et a1 1984 ( J ) ; Scott-Smith & Skinner 1984b (A,P,S);Mitchell1985(P,A,C,L. , s, J )

APPENDIX 3

Alphabetical listing of rock suites discussed in the Paper ARG Argyle, W Australia (AZZ) Azzaba, Algeria, Africa (BAL) Baikal Rift-Aldan Shield, U S S R. BOB Bobi and Seguela, Ivory Coast, Africa (BOH) Bohemian Massif, Czechoslovakia CHE Chelima, Andhra Pradesh, India

Lamprozte5 and K-rzch zgneozls rocks

(CHN) (C J) (COC) (COL) COR (CSN) DSV - -

(FOR) (GDW) GSB I ILM (HM) HOL

K A M (KNX) (LAC) L.II LTJ A M A P MBAY (NHB) (NSW) N W I

Channel Islands, U K Campos de Jordao, Brazil Coc Pia, N Vietnam Colima Graben, Mexico Sisco, Corsica, France Central Sierra Nevada, California Deep Spring Valley, California Enoree Vermiculite, S Carolina Fortification Dyke, Colorado Gondwana Coalfields, India Gaussberg, Antarctica Holmeade Farm, U K Highwood Mountains, Montana Holsteinsborg, W Greenland Hills Pond, Kansas Kamas, U tah Knox County, Maine Laacher See Province, Germany Leucite Hills, Wyoming Luangwa Graben, Zambia Murcia-Almeria province, Spain Mount Bayiiss, Antarctica Navajo-Hopi Buttes, Arizona Lake Cargelligo Area, NSW, Australia N W Italy

P A M Pamir, U S S R P E N Pendennis, U K . PIS Orciatico, Pisa, Italy P D Piedade, Brazil P P Priestly Peak, Antarctica PPS Postmasburg, Pneil etc S Africa P R A Prairie Creek, Arkansas (RP) Roman Province, Italy (SAB) Santo Antonia d a Barra, Brazil (SAC) Sacramento, Br

az

il SB Smoky Butte, Montana (SEW) Seward Peninsula, Alaska (SRE) Srednogorie, Bulgaria (SUNN) Sunnfjord, Norway (TAN) Toto-.Ankole, Birunga, Uganda (TB) Two Buttes, Colorado (TUSC) Tuscany, Italy W K B W Kimberley, Fitzroy Basin, W Aus-

tralia

Those suites in parentheses are not lamproites but merely K-rich rocks; those not in parentheses conform to the present definition of lamproite renru rlricto

Refer enses

ALIEN, D G , PANIELEYEV, A & ARMSIRONG, A T 1975 Porphyry copper deposits of the Alkalic Suite Can Inst M n Spec 15,402-14

ANDERSON, 0 L , BREED, W 1 , BREED, C S , CHIDESIER, A H , MCGEICHIN, T R & SHOE- MAKER, E M 1970 Field guide to kimberlite- bearing diat~emes of northern Arizona-southern Utah including stops at Hopi Buttes, Monument Valley and Grand Canyon In! Symp on hfechan- icalPropert~es and Procerrer of the Mantle June 24- 28 1970, Flagstaff, Arzzona, 52 pp

ANDREWS, J R & EMELEUS, C 1971 Preliminary account of kimberlite intrusions trom the Freder- ikshab district SW Greenland Geol S u ~ u Green-. land Rep 31,26 pp

AOKI, K I & KURASAWA, H 1984 Sr-isotope study of the tephrite series from Nyamuragira volcano, Zaire Geochem 1 18,95-100

APPARADHANULU, K 1962 Minette arid riebeckite- kalisyenite dykes in some Upper Cuddapah rocks, Kulnool district, Andhra Pradesh Rec geol Siau Ind~a, 94(2), 303--4

APPLEION, T D 1972. Petrogenesis of potassium-rich lavas trom the Roccamonfina volcano, Roman Region, Italy J Petrol 13, 425-56

A ~ c u r o s , R J & SMIIII, D 1979 E:clogite, pyroxenite and amphibolite inclusions in the Sullivan Buttes latite, Chino Alley Yavapai County, Arizona In: BOYD F R & IMEYER, H 0 A (eds) The Mantle Sample Inclusions in Krmberliter and Other Volcan- icr Proc ?ndfnr Kimberlite Conf Vol 2 pp 309-

17 American Geophysical Union, Washington, % n UL,

ARIMA, M & EDGAR, A D 1980 Stability of wadeite (Zr,K,Si,O,,) under upper mantle conditions: petrologicalimplications Contrlb Mineral Petrol ,,

72, 191-5 - & - 1981 Substitution mechanisms and

solubility of titanium in phlogopites from rocks of probable mantle origin Contrib Mineral Petrol 77, 288--95 - & - 1983 High pressure experimental studies

of a katungite and their bearing on the genesis of some potassium-rich magmas of the West Branch of the African Rift I. Petrol 24, 166-87.

ATKINSON, W 1. 1982 Diamond discoveries in the Kimberley, Western Australia Tranr hzrt Min Metal1 91A, 135-7

-, HUGHES, F E & SMITH, C B 1982 A review of the kimberlitic locks of'western Australia Term Cognira, 2, 204

-- & - 1983 A revlew of the k~mberlrt~c rocks of Western Australia Proc 6th A~irtrahan Geology Conf , pp 284-5 Geological Society of Australia, Sydney - , -- & -- 1984a A review of the kimberlitic

rocks of western Australia In: KORNPROBSI, T (ed ) Kimberliter I Kimberlirer and Related Rockr, pp 195-225 Elsevier, Amsterdam

- , SMIIH, C B &BOXER, G L . 1984b Thediscovery and evaluation of the Ellendale and Argyle Lamproite diamond deposits, Kimberley region,

Western Australia Soc Min Erig AIME Preprint 84-384

BACMINSKI, S W & SCOII, R B 1979 Rare-earth and other trace element contents and the origin of minettes (mica-lamprophyres) Geochim cosmo- chim. Acta, 43,9 3-100

- & SIMPSON, E L 1984 Ti.phlogopites of the Shaw's Cove minette: a comparison with micas oi other Iamprophyres, potassic rocks kimherlites and mantle xenoliths Am Mineral 69,41-56

BAGSHAW, A N., DORAN, B H , WHITE, A H & WIIIIS, A C 1977. Crystal strccture of a natural K.bearing hexatitanate isostructural with K,Ti,O,, Atist I. Chem 30, 1195-200

BAILEY, D K 1974 Continental rifting and alkaline magmatism Iri: SGJRENSEN, H (ed ) The Alkallne Rocki, pp 148- 59 Wiley, New York

- 1982 Mantle metasomatism-continuing chemi- cal change withir the Earth Nature Lond 296. 95-30

BALASUBRAHMANYAN, M. N , MIJRIY, M K , PAUL, D K & SARKAR, 1978 Potassium-argon ages of Indian kimberlites I Geol Soc India, 19(12), 584- 5

BANERJEE, S 1953 Petrology of the lamprophyres and associated rocks of Raniganj coal field Indian Mineral I l,9-29

BARBERI, F , BIZOUARD, H , CAPALDI, G , FERRARA, G , GASPARINI, P , INNOCENII, F , JORON, J L., LAMBREI, B , TREUII, M & ALLEGRE, , C 1978 Age and nature of basalts from the Tyrrhenian AbyssalPlain InztzalRep DeepSeaDriN~ngProject, - ~

12 (part I), 509-14 -- & INNOCENII, F 196'7 Le rocce Selagitiche di

arciatico e Montecatini in Val di Cecina Atti Soc Tosc PisaSci Nar Mem P V Ser A, 74, 139-80

-- , FERRARA, G , KELIER, & VILLARI, L 1974 Evolutronof Aeolian arc volcan~sm (southern Tyrrhenian Sea) Earth planer Sci Lett 21, 269- 76 - , SANIACROCE, R & VAREI, J 1982 Chemical

aspects of rift magmatism In: PALMASON G (ed.) Continental and Oceanv Rifts, pp 223-58. Ameri., can Geophysical Union, Washington, DC

BARBERI, M , PENIA, A & I'URl, B 1975. 0 and Sr isotope ratios in some ejecta from the Alban IIills volcanic area, Roman comagmatic region Conrrib Mineral Petrol 51, 12'7-33

BARDEI, M G 1977 Geologie du Diamanr, Vol 1 Editions BRGM no 83, Paris

-- 1974 Geologie du Diamant, Vol 2 Editions BRGM no 83, Paris

- 197'7 Geologie du Diamant, Vol 3 Editions BRGM no 81, Paris

-- & VACHEIIE, M. 1966 Determination of the ages ofkimherlitesof West Africa 3rdSymp on African Geology, Rep GCL.0 88, pp 15-17 Common- wealth Geological Liaison Office

BAREN, F A VAN, 1948 On the petrology of the volcanic area of the Geonoeng Moeria (Java) Meded Aig Proefitn Landb Buitenzorg lava 60

BARION, M 1976 Melting relations of some ultrapotas- sic volcanic rocks Prog Erp Petrol VERCPubl Ser D, Vol 6, pp 91-4

-- 1979 A comparative study of some minerals occurring in the potassium-rich alkaline rocks of the Leucite Hills, Wyoming, the Vico Volcano, western Italy, and the Toro-Ankole Region, Uganda Neues ib Mineral Abh ,137(2), 11 3-34

-&VAN BERGEN, M J 1981 Green clinopyroxenes and associated phases in a potassium-rich lava fromtheLeuciteHills, Wyoming Conrrib Mineral Petrol 7'7,101-14

--&HAMILTON, D L 1978 Water-saturatedmelting ielations to 5 kilobars of three Leucite Hills lavas Contrib Mineral Petrol 66, 41-9 - & - 1979 The melting relationships of a

madupite from the Leucite Hills, Wyoming, to 30 kb Contrib. Mineral Petrol 69, 133-42

-&- 1982 Water saturatedmeltingexperin~ents bearing upon the origin of potassium-r ichmagmas Mineral Mag 45,267-78

- & WOOD, B 1 1976 Equilib~ation of orendite with lherzolitic mineral assemblages: a combined experimental/theoretical approach Prog Exp Petrol, NERC Piibl Ser D, Vol 6, pp 90-1

BASIIN, E S 1906 Some unusual rocks from Maine, 1 Geol 14, 173-87

BASU, A R. & TAISUMOIO, M 1980 Nd-isotopes in selected mantle-derived rocks and minerals and their implications for mantle evolution Cbnrrib Mineral Perrol 75,43-54

BEGER, P J 1923 Der chemismus der lamprophyre In: NIccrr, P (ed,)Geiteins.undMineralProu~nzen, Vol, 1 pp 448-51 Verlag Gebruder Borntraeger, Berlin.

BELL, K & POWELL, J L 1969 Strontium isotopic studies of alkalic rocks: the potassium-rich lavas of the Birunga and Taro-Ankole regions, east and central equatorial Africa 1 Petrol 10, 536-72 - & - 1970 Strontium isotopic studies ot alkalic

rocks: the alkalic complexes of eastern liganda Geol Soc Am Bull 81,3481-90

BELION, H 1981 Chronologique radiometrique (K- Ar) des manifestations magmatiques autour de la Mediterranke occidentale entre 13 Ma et 1 Ma Proc In: Cbnf CJrbino Un~versity Italy, pp 341- 60

- & LEIOUSEY, J 1977 Volcanism related to plate tectonics in the Western and Eastern Mediterra. nean, In: BYU D U ~ A L B & MONIADERI L . ( c ~ s ) Int. Symp. on Mediterranean Basins, pp 165-84 Editions Techniq, Paris

BERENDSEN, P., CUIIERS, R L , MANSKER, W L & COLE, (; P 1985 Late Cretaceous kimberlite and lamproite occurrences in E. Kansas, IJ S A Geol Soc Am Abstr Progrn 17, 151

BERGMAN, S C & BAKER, N . R 1984 A new look at the Proterozoic dikes from Chelima, Andhra Pradesh, India: diamondiierous lamproites? Geol Soc Am Abstr Progrri 16(6),444

-- & The Chelima dikes, Andhra Pradesh, India: diamondiierous lam~roites? Submitted to Nature Lond

- , DIJNN, D P & KROL, L G 1985 Petrology and eeochemlstrv of the Llnhalsal Mlnette. Karamu Elver, cential Kal~mantan Abitr Geol 4rsoc Can Proqm 10, A4

BESI, M G 1975 Migration of hydrous fluids in the upper mantle and potassium variation in calc- alkaline rocks Geology, 3,429-32

-- , HENAGE, L. F & ADAMS, J A S 1968 Mica peridotite, wyomingite, and associated potassic igneous rocks in northeastern Utah Am .Minerai 53, 1041-8

BESWICK, A E 19'76 K and Rb relations in basalts and other mantle derived materials Is phlogopite the key? Geochim cormochrm. Acra, 32 1167-84

BICKFORD, M E , MOSE, D E , WEIHERILL, G W & FRANKS, P C 1971 Metamorphism of Precam. brian graniticxenoliths in arnica periodite at Rose Dome, Woodson County, Kansas Part I , Rb41 isotopic studies Geol Soc Am BUN 82, 286.3--8

BLAXLAND, A B 1976a Geochronology and isotope geochemistry of the Gardar Alkaline complex, South Greenland PhD Theris, University of Edinburgh (unpublished)

- 1976b Rb-SI isotopic evidence for the age and origin of the Ivigtut granite body and associated cryolite body, Sourh Greenland Econ Geol 71, 864-9

BOCCALE~II, M , MANEIII, P , PECCERILLO, A & SIANISHEVA-VASSILEVA, G 1978 Late Cletaceou~ high potassium volcanism in E . Srednogorie, Bulgaria Geol Soc Am Bull 89,439-47

BOEIICHER, A L , MYSBN, B 0 & MODRESKI, P J 1975 Melting in the mantle: phase relationships in natural and synthetic peridotite-H20 and peri- dotite-H,O-CO, systems at high pressures Phyr Chem Earth, 9,855-68

- & O'NEK., J R 1980 Stable isotope, chemical and petrographic studies of' high-P amphiboles and micas: evidence for metasomatism in the mantle source regions of alkali basalts and kimbes- lites Am J. S C I BOA, 594-621

BOLIVAR, S L 1977 Geochemistry of the Prai~ie Creek, Arkansasand Elliott County, Kentucky intrusions PhD Thesis, IJniversity of New Mexico (unpub- lished). - 1982 'The P~air ie Creek kimberlite, Arkansas In:

MCF~RLAND, J D , 111 (ed ) Conr~ibutions to the Geoloyy of Arkanrar Stare o,f Arkanrar Geological Commirsion Mirc Pub1 18, pp 1-21

- 1984 Anoverview of the Prai~ie Creek intrusion, Arkansas Soc Min Enz .AIMEEallMeet October 1984, Preprrnt 84-346

- & BROOKINS. D G 1979 G e o ~ h ~ s i c a l and Rb.Sr study of the' prairie Creek, A R kimberlite i n : BOYD, ?I R & MEYER, H 0 A (eds) Kimberlirer Diatren,er and Diamondr . their Geology Petrology and Geochemistry, Proc 2nd Ini Kimberlrte Conf, Vol 1, pp 289-99 American Geophysical Union, Washington, DC

BORLEY, G D 1967 Potassium-rich volcanic rocks from Southern Spain Minerul Mag 36, 164-79.

BORSI, S , FERR~RA, G & TONGIORGI; E 1967 Determinazioni con il metoda K/Ar delle rocce magmatiche della Toscana Boll Soc Geol Italy, 86,401-10

BOUIWELL, I M. 1912 Geology andoredepositsof the Park City District, Utah U S Geol Suru Prof Pap 77,231

BOWEN, C F 1915 Possibilities of oil in the Porcupine Dome, Rosebud County, Montana U S Geol Suru BUN 621,61-70

BOWEN, N L 1928 Evol~ition of the Igneour Rockr Princeton University Press, Princeton, NJ

BRADLEY, W ?I 1964 Geology of Green River Formation and associated Eocene rocks in SW Wyoming and adjacent parts of Colorado and Utah U.S Geol Surv P ~ o f Pap 496A, A1-A86

BRANNER, J C &BRACKEII,R N 1889Theperidotite of Pike County, Arkansas Am. I. Sci 38, 50-9

BRAVO, M S & O'HARA, M J 1975 Partial melting of phiogopite-bearing synthetic and garnet..lherzo- iites Phyr Chem Earth, 9 , 845-54

BRIQIIEU, L.., BOUGAULI, H & JORON, J L 1984 Quantification of Nb, Ta, Ti and V anomalies in magmas associated with subduction zones: petro- genetic implications Earth planet Sci Lett 68, 297-308

BROOKINS, D G , D ELLA VALLE, R S & BOLIVAR, S L . 1979 Significance of uranium abundance in United States kimberlites: In: BOYD, H R & MEYER, H 0 A (eds) Kimberiiter Diairemer and Dramondr Their Geology Petrology and Geochem- istry Proc 2nd Inr. Kimberlite Conf, Vol I, pp 280-8 American Geophysical Union, Washing- ton, DC

BROOKS, C K , FAWCEII, 1 J , GIITINS, J G & RUCKLIDOE, J C 1981 The Batbjerg complex, east Greenland: auniqueultrapotassicCaledonian intrusion Can J EarthSci 18,274-85 - , NOE-NYGGARD, A , REX, D C & ROENSBO, J C

1978 An occurrence of ultrapotassic dikes in the neighborhood of' Holsteinsborg, West Greenland Bull geol SOL Denmark, 27,l-8

BROUWER, H A 1909 Glimmerleucitbazalt van Oost- Borneo Verrl Kon Aknd Wetenrch Amrterdam wir Nat Afd 18,8,851.

BTJCKING, H 1899 Ber Naturforrch Ger Freibu~g, i(1l) 78

BUIE, B F 1941. Igneous rocks of the Highwood Mountains, Montana, 111, Dike and related intru-. sives Geol S O L Am BUN 52, 1754-807

- & STEWARI, 0. F 1954 Origin of vermiculite at Tigeiville, S Carolina Geol Soc Am BUN 65, 13 56-7

BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEO-. PHYSICS, 1976 Geological Map of Australia (1/2,500,000 scale, 4 sheets), Canberra, A C 1

CARABALLO, J M 1975 Geoquimica de las rocas Iamproiticas espanolas PhD Thesis, University of Madrid (unpublished)

CARMICHAEL, 1 S E 1967 The mineralogy and petrology of the volcanic rocks from the Leucite Hills, Wyoming Contrib Mineral Petrol 15, 24- 66

-- , NICHOLLS, I , SPERA, F J , WOOD, B J & NELSON, S A 1977 High temperature properties of silicate liquids: application to the equilibration and ascent of basic magma Phil 7ranr R Soc Land Se, 11,286,373-431

- , TURNER, F S & VERHOOGEN, J 1974 Igneous Petrology, ivlcGraw.HilI, New York

CARR,S G &OLLIVER, J G 1980 Olivine basaltdyke

near Terowie Or Geol Noter Geol Sirrv 5 4urt - 73, 2-7.

CARRARO, F & FERRAR, G 1968 Alpine 'Tonalite' at ~Miagliano, Bielia (zonadiorite-Kinzigitica) Schwetz Mineral Pet~ogr Mttt 48, 75-8

CHAIIERJEE, S C 1974 Petrography ofthe Igneous and Meranrorphic Rockr of irtdla, 391 pp Macmillan, Bombay

CHAYES, F 1976 Independen! exploration of the database and reduction repertoire of the petro. gra~hicinformation system Carnea~e Inrtn Warh ?b -75,79 1

-

CIVEIIA, L., INHOCENTI, F., M ~ N E I I I , P , PECCERILLO, A & POLI. G 1981 Geochemical characteristics of potassic volcanics Gom Mts Ernici (southern Latium, Italy). Contrib Mineral Petrol 78, 37-47

- , ORSI, G 8: SCANDONE, G 1978 Eastwards migration of the Tuscan anatectic magmatism due to anticlockwise rotation of the Appenhines, Nature Land. 276,604-6

CLARK, F W & WASHINGION, H S 1924 The composrtion of the earth's crust Prof Pap U S G S 127

CLEMENI, C R , SKINNER, E M W & SCOTT, B H 1977 Kimberlite redefined Extended Abrtr 2nd Klmberlite Con/ Santa F e N M

COLCHESIER, D M 1982 Geology and petrology of some kimberlites near lerowie, S Australia M Sc Thes~r, New South Wales Institute of Technoi. ogy (unpublished)

- 1983 The geology and petrology of some kimber-, litesnear Ierowie,S Australia,Proc 6thAzistralian Geoloav Conv , pp 282-3 Geological Society of ~ust ra l ra , sydn&

C OLLERSON. K D & MCC~JLLOCH M 1982 Nd and . Sr isotope geochemistry of leucite-bearing lavas from Gaussberg, Eastern Antarctica J geoi Soc Ausr. 30.

CONDIE, K C 19'76 Plate tectonics andcrurralevoiur~on Pergamon Press, Inc , New York.

CORNELISSEN, A K & VERWOERD, W J 1975 The Bushmanland kimberlites and related locks Phys Chem Earth, 9,71-SO

COSGROVE, M E 1972 Geochemistry of the potassium- rich Peimian volcanic rocks of Devonshire, Eng- land Conrrib Mineral Petrol. 36, 155-70

Cox, K G , HAWKESWORIH, C J , 0 NIONS, R. K & APPLETON, J D 1976 Isotopic evidence for the derivation of some Roman region volcanics from anomalously enriched mantle Conrrib Mineral Petrol 56, 173-80

CRAWFORD, A R 1969 India, Ceylon and Pakistan: new age data and comparisons with Australia Natlire Land 223, 780-4.

- & COMPSION, W 1970 Age of the Vindhyan SystemsofPeninsular India Q J Geol Soc Lnnd 125, 351-71

- & 1973 An age of the Cuddapah and Kurnoolsystems, southernIndia J geol Soc Aurt 19, 4

CRIIIENDEN, M D & KIRSILER, R W 1966 Isotopic dating of intrusive rocks in the Cottonwood area, Utah Geol Soc Am Spec Pap 101,298-9.

CROSS, C W 1897 The igneous rocks of the Leucite

Hills and Pilot Butte, Wyoming Am J Sci 4 , 1 15--41 - 1906 Prowersose (syenitic lamprophyre) from

Two Buttes, Colorado J Geoi. 14, 165-72 CULLERS, R L., FUMAKRISHNAN, S , BERENDSEN, P &

GRIFFIN, 'I 1985 Geochemistry and petrogenesis of lamproites, late Cretaceous age, Woodson County, Kansas, ZJ S A Geochim cosmochim Acta 49, 1388-402

CUNDARI, A 1973. Petrology of the leucite-bearing lavas in New South Wales J geol Soc Aust 20, 465-92

-- & FERGUSON, A K 1982 Significance of the pyroxene chemistry from leucite-bearing and re- lated assemblages Tschermaks Mmerai Petroar M ~ t r 30, 189--264

- & O'HARA, M. J 1976 Experimental study at atmospheric and high pressures of a mafic leucitite from New South wi les , Australia Prog ~ r p Petrol 3rd Rep NERCPub Ser D, 6, 260-1 - , RENARD, 7 G R & GLEADOW, A J W 1978

IJranium-potassium relationship and apatite fis.. sion track ages tor a differentiated leucite suite from New South Wales (Australia) Chem Geol 22, 11-20

CURRIE, K L , CURTIS, L W & GIIIINS, J 1975 Petroiogv of the Red W ~ n e alkaline com~lexes ~ e n t r a r ~ a b r a d o r and a compa~ison with the llimaussaq complex, SW Greenland Geol Suru Can Pap 75(1A), 271-80

DAL PI .~z , G V , HUNZIKER, J C & MARTINOIII, G 1973 Excursion to the Sesia zone of the Schw mineral.petrograph gesellschaft, September 70th to October 3rd, 1971 Schweiz Mineral Petrogr w t t 53,447-90

-, VENIUREIL,~, G & SCOLARI, A 1979 Calc.. alkaline to ultrapotassic postcollisional volcanic activity in the internal northwestern Alps Mem S ~ I . Geol 32

DALY, R A 1910. Origin of alkaline rocks Geoi Sac .Am Bull 21,87-118

- 1914 Igneous Rocks and their Or~gm, 1st edn McGraw-Hill, New York

- 1933 Igneous Rockr and the Depthr of the Earth, 598 pp Hafner, New York

DAWSON, J B 1967a A review of the geology of kimberlite In: WYLLIE, P J (ed ) Ult?arnafi~ and RelatedRocks,pp 241-51 Wiley, New York 1967b Geochemistry and origin of kimberlite i n :

WYLLIE P J (ed) Ultrnmafic and Related Rocks, pp 269-78 Wiley, New York.

- 1970 'The structural setting of African kimberlite magmatism i n : CL~FFORD, T N & GASS, I. G (eds) Afiican Magmatirm and I'ecronics, pp 321- 35 Oliver & Boyd, Edinburgh - 1979 New aspectsof diamondgeology In: FIELDS,

7 E (ed ) Diamondr, pp 539-54 Academic Press, New York

- 1980 Kirnberi~ter and therr .Xenolith,, 252 pp Springer New York - 1981 Contrasting types of upper mantle metaso.

matism? In: KORNPROBSI, J (ed.) Kimberlites II The illanile and Crust-Mantle Reiationships pp 289-94 Elsevier, Amsterdam

Lamproites and K

1987 The kimberlite clan: relationship to olivine

B G J (eds) Alkaline I,neous Rocks Geol So< Spec pub/ 30, pp 95-10i

& SMIIH. J. V 1977 The MARID (mica- amphibolerutile.ilmenite-diopside) suite of xen- oliths in kimberlite Geochlm rormochim Acta, 41, 309-23

DE MARCO, L 1959 Su alcuni filoni lamprofirici radioattivi del complesso Sesia.L.anro Stud Rich Dm Geomin Cnen, 1, 1-30

DE ROEVER. W P 1075 Belts wrth scattered leucrte occurrences indicate direction of' dip of coeval subduction zones Petrologie, 1, 37-42

DERRICK, G M & GELLAILY, D C 1972 New leucite lamproites from the west Kimberley, western Australia Bur Mi11 Rerourcer Aus t , BUN 125, 103-19.

DODGE, F C W & MOISRE, J G 1981 Late Cenozoic volcanic rocks of the southern Sierra Nevada, California: 11 Geochemistry Geol Soc Am Bull 92, 1670-761

DOLFI, D. , FARINAIO, R , IR lGlLA, R & HAMILION, D L 1976 Some experimental and thermodynamic evidences bearing on the origin of potassic volcan- ics from central Italy. P ~ o c Int Congrers Thermal Waterr, Geothelmal Energy and Volcanism of the Mediierranean Area, Vol. 3 Natl Tech Univ , Athens, Greece pp 43-59

DORI. W 1972. L.ate Cenozoicvolcanismin Antarctica In: ADIE, R J (ed) Antarctrc Geol Geophys , pp 615-52 Universitetsforlaget, Oslo

DRYGALSKI, E YON 1904 The German Antarctic Expedition Geogr 1 24, 129-52.

DIJBEAU, M I & EDGAR, A D 1985 The stability of priderite up to 30 kb: inferences on its potential as a reservoir for K , Ba and Ti in mantle sources for lamproitic magmas Geol Assoc Can Progm ~ b s ; , 10, A15 -

DIJDA. A & SCHMINKE. H V 1978 Quaternary basanites, melilite nephelinites and tephrites from the Laacher See area (Germany) Neuer i b Mineral Abh 132, 1--33

EDGAR, A D 1979 Mineralchemistry andpetrogenesis of ultrapotassic-ultramafic volcanic rocks Conirib Mineral Petrol 71, 1'71-5

-- 1983 Relationship of ultrapotassic magmatism in the western U S A, to the Yellowstone plume Ne~ier i b Mineral Abh 147, 15-46

- & ARIMA, M 1981 Geochemistry of three potassium-rich lavas from the west branch of the African rift: inferences on their genesis Neues Jb Mineral Monatsh 539-52

- & - 1983 Conditions of phlogopite crystalli- zation in ultrapotassic volcanic rocks Mineral Mag. 47, 11-19 & CONDLIFFE, E 1978 Derivation of K-rich

ultramafic magmas from a peridotitic mantle source Narure Land. 174,639-40 -- , , BARNEI.I, R L & SHIRRAN, R 1 1979 An

experimental study of an olivine ugandite magma and mechanisms f o r the formation of its K-. enriched derivatives i Pet101 21,475-97

-rzch zgneous rocks I77

-, GREEN, D H & HIBBERSON, W 0 1976 Experimental petrology of a highly potassic magma i Petrol. 1'7, 339-56

EGGIER, D H 197'7 The principle of the zone of invariant vapor composition: an example in the system Ca0-Mg0-Si0,-C0,-H,O and implica- tions for the mantle solidus Carneaie Inrtn Warh "

Yb 76,428 -33 ERLANK, A J 1970 Distrrbut~onof potassrum ~nmafic

and ultramafic nodules Carnepie Insin Warh Yb - 68,433 - 1973 Kimberiite potassium richterite and the

distribution of potassium in the upper mantle Int Conf on Kimberlztes Cape Town Extended Ab-. rlracts, pp 103-6 Univ Capetown Rondebosch

-&RICHARD, R S 1977 Potassicrichterite hearing peridotites from kimberlite and the evidence they providefot upper mantlemetasomatism Extended Abstr 2nd Kimberlite Con/ Santu Fe, N M ,

-,ArrsoP~, H L , HAWKESWORIH, C T & MENZIES, M A 1982 Chemical and isotopic characteriza- tion of upper mantle metasomatism of' peridotite nodules from the Bulfontein Kimberlite Terra Cognita, 2, 261-3

ESCHER A 1970 Iet~onic/Geolog~cai map o j Greenland 1112,500000 rcalel. Geological Survey of Green i a h , Copenhagen

-

-& WAITERSON, J. 1973 Kimberlitesandassociated rocks in the Holsteinsborg-Ssndre Stromfjord Region, Central West Greenland Grwzland Geol Underr Rapp 55

ESKOVA, E M & KAZAKOVA, M. E 1955 Shcherba- kovite-a new mineral Am Mrneral 40, 788

ESPERANCA, S & HOLLOWAY, J R 1985 An experi- mental study of a mafic minette from Buell park, Arizona Geol Arroc Can Progm Abrtr 10, A17

EWARI, A 1982 The mineralogy and petrology of Tertiary-Recent orogenic volcanic rocks: with special reference to the andesitic-basaltic compo- sitional range. I n THORPE, R S (ed ) Anderires, pp 25---95 Wiley, New York & LEMAIIXE, R W 1980 Some regional compo-

sitional ditierences within Tertiary-Recent oro- genic magmas In: LEMAIIRE, R W & CUNDARI, A (eds) Chemical Characterzzatzon of Tectonic Provmce. Chem Geol 30,257-83

FALLOI, P. & JEREMINE, E 1932 Remarque sur une varit-t& nouvelle de jumillite et sur I'extension des laves de ce groupe C R Cong? Narl Soc Savanter 1929,l-13

FARQUHARSON, R. A 1920 Petrologic work Annu Rep geol Sirrv PV Aust 1919,42

- 1922 Petrologic work Annzi Rep Geol Suro W A~crt 1921, 56

FAURE, G 1977 Prmciples o / I ~ ~ t o p e Geology, 464 pp Wrlev. New York

- & P ~ W E L L , 1. L 1972 Strontrum Isorope Geology, 188 pp Springer, New York

FERAUD. I . FORNARI. M . GEFFROY, T & LENCK, P . . 197'7 ~ inha l i sa t ions arsenit-es et ophiolites: le filon a reaigar et stibine de Matra et sa place dans le district a Sb..As-Hg de la Corse alpine BUN B R G M 2,11,91-112

FERGUSON, A K & CUNDARI, A 1982 Feldspar

178 S C Bergmnn

crystallization trends in leucite-bearing and related assemblages Contrib. Mineral Petrol 18,212-8

FERMOSO, M L 1967a Composition quimica de las sanidinas de las rocas lamproiticas espanolas Esrud Geol 23,2940

- 1967b El diopsido de las rocas volcanicas de lumilla Estud Geol 23, 31-3,

FERNANDEZ, S & HERNANDEZ.PACHECO, A 1972 Lamproitic rocks of Cabezo Negro, Zeneta, Mur- cia E:rtud Geol Inrt Inuert Geol Lucar Mallada, 28,267-76

FERRARA, G , LAIJRENZI, M A , TAYLOR, H P , TONARINI, S & TURI, B 1985. An oxygen and strontium isotope study of the Alban Hills volcanic complex, Italy Earth planet Sci Lett 75, 13- 72 ""

, MARIINEZ, M P , TONARIN~, S. & IURI, B 1980 Oxygen and strontium isotopic correlation in volcanic rocks from Mt Vulsini district (N Latium, Italy) Int. Conf on Geochronology COY.. mochrono1og)i and Isoroprc Geochemistry Extended Abrtracrr, pp 95-6 U S Geol Survey, Washing-

County Kansas Part 2, Petrologic and mineralogic studies Geol Sac Am Bull 82,2869-90

FRANISESSON, E V 1968 The Petrology ojrhe Kimber- liter, 194 pp (Translated by D A Brown, Australian National University, Canberra, 1970 )

FRASER, K J , HAWKESWORIH, C J , ERLANK, A 3 , MIICHELL, R H & SCOTT-SMIIH, B H 1985 SI, Nd and Pb isotope and minor element geochemis- try of' lamproites and kimberiites Earth Planet Sci Lett 76, 57-70

FRIEND, C R I . & JANARDHAN, A S 1984 Mineral chemistry of coexisting phases from shonkinitic rocks, Salem, Tamil Nadu, India, Mineral Mag 48, 181-93

FROMAGEI, J I933 SUI la presence de roches intrusives alkalines dans la zone charsiee neotriasique des plateaux calcaires du Tonkin occidental C R Acad Sci Parir, 197, 651-3

FURNES, H , MIICHELL, J G , ROBINS, B , RYAN, P & SKJERLIE, F . J . 1982 Petrography and geochemis- try of peralkaline, ultrapotassic syenite dykes of Middle Permian age, Sunnfjord, W Norway

ton Norsk Geol ~idrrkr-62, 147-59 FIIZGERALD, W Y 1907 Reports on portions of the FI,SIER, 1956 Las erupciones delleniticas del

Kimberieys (1905-6) W Aurt~alia Parliamentary Torciario superior de la Fosa de Vera (provincia Paper 19 de Almeria) Ertud Geol 20,299-314

FODEN, J D 1983 The petrology of the calcalkaline lavas of Rindjani Volcano, East Sunda Arc; a

- & D E PEDRO, F 1953 Estudio petrologico de las rocas volcanicas lampioiticas de Cabezo Maria model for island arc petlogenesis J Petrol 24,98- . - - (Almeria) Eeiud Geol Inst Lucar Malluda Inuert

15U. FOLEY, S F 1982 Mineralogy, geochemistry, petroge-

nesis and structural relationships of the Aillik Bay alkaline intrusive suite, Labrador, Canada M Sc Theris, Memorial University Newfoundland (un- published)

-- 1984 Liauid immiscibilitv and melt segregation - - in alkaline lamprophyies from Labradoi Lithos, 17 177-17 . , . - . - .

.- 1985 The oxidation state of lamproitic magmas Tschermaks Mineral Petrol Mitt., 3, 217-38

-- , 'TAYLOR, W R & GREEN, D I1 1986a The role of fluorine and oxygen fugacity in the genesis of the ultra~otassic rocks Contrib Mineral Petrol, 94, 183-62

-, TAYLOR, W R &GREEN, D H 1986b Theeffect of fluorine on phase relationships in the system K A ~ S ~ O , - M ~ , S ~ O , . . S ~ ~ , at 28 kbar and the solu- tion mechanism of fluoiine in silicate melts Contrib Mineral. Petrol 93, 46-55.

-, VENIURELII, G , GREEN, D H & IOSCANI, L in review The ultrapotassic rocks: characteristics, classification and constiaints for petsogenetic . - models

Fox, C S 1930 The Jhar~aCoalfield Mem Geol Suru India 56 255

FRANKS, P C 1959 Pectolite in mica peiidotite, Woodson C;ounty, Kansas Am Mineral 44, 1082- 6 - 1966 Ozark Precambrian-Paleozoic ielations:

discussion of igneous rocks exposed in E Kansas Bull A m Arroc Petrol Geol 50, 1035-42

- , BICKFORD, M E & WAGNER, H C 1971 Metamorphism of Precambrian granitic xenoliths in a mica peridotite at Rose Dome, Woodson

\. .... ~ ~ - ~ ~ ~ , -~

Geol Pub1 20, pp 477--508 - & GASIESI, P 1964 Estudio petioiogico de las

rocas lamproiticas de Barqueros (provincia de Murcia) Eriud Geol 20, 299-331

-. - , SAGREDO, J . & FERMOSO, M L . 1967 Las rocas Iamproiticas del S E de Espana Eriud Geol 23,35-69

- , IBARROLA, E & LOBAIO, M P 1954 Analvsis quimacos de rocas espanolas publicados hosta 1952 C 5 I C hlonogr Inrt Lucur Mallada In~er t Geol 14

GALLAGHER, M J 1963 Lamprophyre dykes from Argyll Mineral Mag 33,415-30

GALLO,F 1984 TheKamafugitic rocksof SanVenanzo and Cuppaello, Cential Italy, ~Veuer Jb Mineral Monatsh 115, 198-210

GARLICK, G D 1966 Oxygen isotope fractionation in igneous rocks Earthplanet Sci. Lett 1, 361-8

GARLICK, H 1 1979 Australian diamond prospects The story so fai Indust Miner (Feb) 137, 17- ?9

GATES, 0 1959 Breccia pipes in the Shoshone ranges, 1

Nevada Econ Geol 54,790-815 GEOLOGICAL SURVEY O t IIALY, 1961 Carla Geoiogieo

D Iiaiin (ill 000 000 rcale Zsheets), Rome GESI,D. E & MCBIRNEY, A R 197'7 Geneticrelations

of shoshonitic and absarokitic magmas, Ahsaioka Mountains, Wyoming J Volcano1 geotherm Rrr 6,85-104

GHOSE, C 1949 Apetrochemicaistudy of lamprophy~es and associated intrusive rocks of' the Jhaiia coalfield Quart J Geol M n MetaN Soc India, 21,133-47

GIARDINI, A A & MELION, C E 1975a The nature of

Lamprortes and K

cloud.iike inclusions in two Arkansas diamonds Am M~neral 60,931-3

-- & -- 1975b Chemical data on a colorless Alkansas diamond and its black amorphous C- Fe-Ni-S inclusions Am Mineral 60,934-6

-- &- 1975c Gases released from natural and synthetic diamonds by crushing under high vac-. uum at 200°C, and their significance to diamond genesis Fortrchr Mineral 52, 455-64

-- , FIURSI, V J , MEIION, C E. & STORMER, J C 1974 Biotite as a primary inclusion in diamond: its nature and significance, Am Mineral 59, 783.. 0

GILBERI, G K. 1896 Laccolites in S E Colorado I Geol 4,816-25

GILL, J B 1981 Orogenlc ande~ites andplate tectonics Springer.Verlag, New York

GII'IINS, 1 1979. 'The feldspathoidal alkaline rocks In: YODER, H. S , JI (cd ) The Euolut~on o/the Igneo~rr Rocks, Fifrierh Ani~iuersary Perspecf~ves, pp 351- 9 0 Pxinceton University Press, Princeton, NJ

-. , FAWCETI, J J , BROOKS, C. K & RUCKLIDGE, J . C 1980 Intergrowthsofnepheline-K-.feldspar and kalsilite-.K.feldspar: a reexamination of the useudo-leucite ~ rob lem Contrib Mineral Perrol 73,119-26

- , MACINIYRE, R M & YORK, D 1967 The ages of carbonatite complexes in eastern Canada Can I Earth SCI 4,651--5

GIAZNER, A F 19'79 Geochemistry of ultrapotassic metasomatism in the Sleeping Beauty volcanic area, central Mojave Desert, California Geol Sac Am Abrzr Progm. 11,79-80

- & SIORK, A L 1976 Ultrapotassic, silica. rich Tertiary volcanic necks from the Mojave Desert, California Geoi Soc Am Abrtr Progm 8, 886

GOGINENI, S V , MELION, C E & GIARDINI, A A 1978. Some petrological aspects of the Prairie Creek diamond-.bearing kimberlite diatreme, Ar- kansas C o n t ~ ~ b Mineral. Petrol 66, 251-61

GOLDscHMm1, V M 1933 Grundlagen der quantita- tiven Geochemie Fortschr Mineral Krirt Perrog 17, 112-56

GO1 Es, G G 1967 Trace elements in ultramafic rocks In: WYLLIE, P , J (ed.) l/itrarna/ic andrelatedrocks, I Wiley and Sons, New York, 352-62

GRAPES, R H 1975 Petrology of the Blue mountain Complex, Marlbolough, N Z I Petrol 16, 371- 428

GREGORY,G P 1969 Geochemicaldispersionpatterns related to kimberlite intrusives in N America. PhD 7heris, Royal School of Mines, Imperial College, London (Unpublished)

- & T o o ~ s , J S 1969 Geochemical prospecting for kimberlite Q J Colorado Schooi Mines, 64, 265- 105

GROZDANOV, L 1979 Chemistry and genesis of biotite from lamnroites in the vicinitv of the villaee of Svidnya, histrict of Sofia (~u l i a r i a ) , Doki >ole ~ k a d . N a u k , 32,341-4

-

Gnuas, P L C 1965 Undersaturated potassrc lavas and hv~abvssal rntrnsives in N Johore Geol Mae

GUMEEL, C W YON, 1874 Die Palaolithischen Erup- tn~gerteinedes Fichtelgebirges. Franz, Munich

GUPIA, A K & YACI, K 1980 Per~ology and Genesis oJLeucite-bearing Rocks, Springer, New York

- , YAGI, K , HARIYA, Y , ONIJMA, K 1976 Experi- mental lnvestigatron of some synthetic leuc~te rocks under water oressures Proc Iau Acad Sci 52,469-72

-- , LEMAIIRE, R W , HAUKKA, M I & YAGI, K 198'3 Geochemical studies on the carbonated apatite glimmerites from Damodar Valley, India Proc lap Acad Sci 59B, 113-16

HAGGERIY', S E 1976 Opaque mineral oxides in terrestrial igneous rocks In: RUMBLE, D (ed.) O i ~ d e s Mineral Soc Am Short Course Notes, Vol 7, pp 101-300

- 1983 The mineralchemistry of new titanatesfrom the Jagersfontein Kimberiite, S Africa: implica- tions for metasomatism in the upper mantle Geochim cormochim .Acra, 47, 1833-854 - , SMYIH, I R , ERLANK, A. J , RICHARD, R S &

DANCHIN, R V 1983 Lindsleyite (Ba) and mathiasite (K): two new chromium-titanates in the crichtonite series from the upper mantle Am Mine~ul. 68,494-505

HALL, A 1974 Weir Cornwaii. Geol Assoc. Guide Book 19 Banham & Co , Colchester, England 39

.- PP, 1982 The Pendennisperalkaline minette Mineral Mag 45,257-66

H ALL, A E. & SMIIH, C B 1985 Lamproitediamonds: are they different? In: GIOVER, J &HARRIS, P G (ed ) Kimberlire Occurrence and Oririn (1n11, W - Austraiia Pub1 8, pp 167-21 1

HARGR~VES. R B & ONSIOII, T C 1980 Paleomae- netic results Lrom some southern African kimber.. lites, and their tectonic significance I geophys Res 85, 3587-97

HARRIS, P G 1957 Zone refining and the origin of potassic basalts Georhrm cosmochirn Acra, 12, 195-208 - 1984 Kimbeilite volcanism In: GIOVER, J E &

IIARRIS, P G . (eds) Kimberlrte Occurrence and Origin Unm W .Au~lraiiaPubl 8, pp 125-42 - & MIDDLEMOSI, E A 1969 'The evolution of

kimberlites Lithor 3, 77-88 HAWKESWORIH, C J , ERLANK, A J , MARSH J . S ,

MENZIES, M A & VAN CALSIEREN, P 1983 Evolution of'tKe continental lithosphere: evidence from volcanics and xenoliths in southern Africa In: HAWKESWORIH, ' J & NORRY, M J (eds) ContinentalBasnIts and Mantle Xenoliths, pp Ill-, 39 Shiva, Orpington

-. , FRASER,K 7 PI ROGERS, N W 1986 Kimberlites and lamproites: extreme products of mantle en- richrnentprocesses Spec Pub Geol Soc S Aj? in press

HAWKINS, D W 1976 Emplacement, petrology and geochemistry of ultrabasic to basic intrusives at Allik Bay, Labrador M Sc. Thesis, Memorial University Newfoundland, St Johns (unpub- lished)

HAWIHORNE, J B 1975 Model 01 a kimberlite pipe Phyr Chem Earth, 9, 1-16

HEALD, K C 1926 Geology of the Ingomar anticline, Treasure and Rosebud counties, Montana U S Geol. Survey Bull 786,l-37

HEARN, B C J: 1968 Diatremes with kimberlitic affinities in north-central Montana Science 159, 622-5 - 1979 Preliminary map of diatremes and alkalic ultramatic intrusions, Missouri River Breaks and vicinity, North Central Montana [i 5 Geol Suru Open File Rep 79-1128 & MCGEE, E S 1982 Garnets in Montana

diatremes: a key to prospecting for kimberlites U S Geol Suru Open File Rep 82-722

-. & -- 1984 Garnet peridotites from Williams kimberlites, north-cent~al Montana, U S A In: KORNPROBSI, J (ed ) Kimberlites 11: The Mantle andCrust-Mantle Relationship, pp 55-70 Elsevier, . . Amsterdam

HEINRICH. E W. 1966 The Geoioevof Carbonatites. 555 pp Rand McNally, New YO-r"k.'555 pp

-- & MOORE, D G TI 1970 Metasomatic potash feldspar rocks associated with igneous alkalic complexes Can Mineral 10, 571-84

HELMSIAEDI, H & GIJRNEY, J J 1984. Kimberlitesof southern Africa--are they related to subduction processes? In: KORNPROBSI, J (ed) Kimberlites I Kimberirter and Related Rocks, pp 425-34 Elsev-. ier, Amsterdam

HENAGE, L F 1972 A definitive study of the origin of lamproites M S Thesis, University of Oregon (unpublished)

HERNANDEZ-PACHECO, F I935 Estudio fisiographico y geologico del territoriocomprendido entre Hellin y Cieza An Uniu Madrid (Cienc ), 4, 1-38

- 1965 Una richterita potasica de rocas volcanicas aicalinas, Sierra de las Cabras (Albacete) Esfud Geol 20, 265.-'70

HERIOGEN, J , LOPEZ-RUIZ, J , RODRIGUEZ-BADIOLA, E., DEMAIFFE, D & WEIS, D 1985 Petlogenesis of ultrapotassic rocks from S.E Spain: trace elements and SI-Pb isotopes Geol Arsoc Can Progm Abstr 10, A26

HIGAZY, A 1954 Trace elements of volcanic and ultrabasic potassic rocks of south-western Uganda and adioining part of Belgian Congo Geol Soc Am ~ : ; l l 65,j9-70

HINIZE, L F 1980 Geological map of Utah (1/500,000 scale. 2 sheets! Utah Geol M~neral Surv , Salt ~ a k e ~ i t ~

HOBSON, B 1892. On the basalts and andesites of Devonshire, known as 'feldspathic traps' Q I Geol Soc 48,496-507

HOEFS 7 & WEDEPOHL, K H 1968 Stroiltiurn isotope studies on young volcanic rocks from Germany and Italy Contrib Mineral Petrol 19, 328-38

HOFMANN, A W , WHIIE, W M & WHIIFORD, D J 1978 Geochemical constraints on mantle models: the case for a layered mantle Yb Carnegie Instn Wash Y b 77, 54-61

HOLM, P M & MUNKSGAARD, N C 1982 Evidence for mantle metasomatism: an oxygen and stron- tium isotope study of the Vulsinian district, central Italy Earrhplanet Sci Lett 60, 376-88

HOLMES, A 1932 The origin of igneous rocks Geol Mag 69, 543-58

- 1950. Petrogenesis of katungite and its associates Am Mineral 35,772-92

--&HARWOOD, H F 1932 Petrology of thevolcanic fields east and southeast of Ruwenzori, Uganda Q I Geol Soc. 88,170-442

- & -- 1937 The volcanic area of Bufumbira Pt I1 Mem Geol. Suru Uganda, 3

HOIUB, F V 1977 Petrology of inclusions as a key to petrogenesis of the Durbachitic rocks from Czech- oslovakia T~chermakr Mineral Petrogr Mitt 24, 13 3-50

HUNZIKER, J C 1974 Rb-SI age determination and the alpine tectonic history of the western Alps Mem Lst Geol Mln Untu Padoua, 31, 1-54

HURLBUI, C S & GRIGGS, D 1939 Igneous rocks of the Highwood Mountains, Montana: Part I, the Laccoiiths Geol Soc Am Bull 50, 1043-112

HURLEY, P. M , FAIRBAIRN, H W & PINSON, W H. 1966 Rb-.Sr isotopic evidence in the origin of potash-rich lavas of western Italy Earth planet Sci Lett 1, 301--6

INNOCENII, F , MANETII, P , MAZZUOII, R , PASQUARE, G & VILLARI, L 1982 Anatolia and NW Iran In: THORPE. R S (ed) Andesites, pp 327-49 Wiley, . . . . London

JANSE, A J A 1984 Kimberlites-where and when In: GLOVER, 7 E & HARRIS, P G (eds) Kimberlite Occurrence and O~igln A Barir for Conceptual Models in Exploration IJniv W Australia Pub1 8, pp 19-62 Perth, W Australia

JAQUES, A L 1983 The ultrapotassic rocks of the West Kimberley region, W A : products of deepseated intraplate volcanism Proc 6th Geological Socrety of Australia Conu , Vo1 9 Geological Society of Australia, Sydney

- & FOLEY, S F 1985 The origin of Al-rich spinel inclusions in leucite from the leucite lamproites of western Australia Am Mineral , '70, 1141--50

- GREGORY, G P , LEWIS, J D & FERGTJSON, J

1982 Theultra-potassicrocksofthe W Kimberley region, W Australia and a new class of diamondi- ferous kimbeilite Terra Cognlta, 2, 251-2

-- , LEWIS, 7 D , GREGORY, G P , FERGUSON, 1 , SMIIH, C B , CHAPPELL, B W & MCCULIOCH, M T 1983 The ultrapotassic, diamond-bearing rocks of the West Kimberley legion, Western Australia Proc 6th Geological Society of Auslral~a Conu , Voi 9, pp 286-7 Sydney

- - - -- -- , & -- 1984a The diamond bearing ultrapotassic (lamproitic) rocks of the West Kimberley region, Westem Australia In: KORNPROBSI, J (ed ) Kimberlrter I Kimberliles and Related Rocks, pp 225--54 Elsevier, Amster-. dam - , & SMIIH, C B 1986 The kimberlites and

lamproites of Western Australia Geol Suru Western Australia Bull 132, Perth, W A

-, WEBB, A. W., FANNING, C M , BLACK, L. P , PIDGEON, R. T , FERGGSON, J , SMIIH, C B & GREGORY, G P 19841, The age of the diamond bearing pipes and associated leucite lamproites of

the west kimberley region, western Australia Bur Mineral Res Aurr Geol Geophys 9, 1-7

JENSEN, H I 1908 The distribution, origin and relationships of alkaline rocks Proc Linn Soc N S W 33,491-588

JEREMINE, E & FALLOI, P 1929 Sur la presence d'une vari&tt de jumillite aux environs de Calasparra (Mnrcia) C R Acad Sci Parir, 188, 800

JEWETI, J M 1964 Geologic map of Kansas (11 500,000 scale) State Geol Surv Kansas

JOHANSSEN, A 1931 A De~criptme~etrography o/Igneour Rockr, Vol 1, University of Chicago Press, Chicago, IL

- 19.33 A Dercripti!ie Petrography oj Igneour Rocks, Vol 2, University of Chicago Press, Chicago, IL,

- 1935 A Dercriptive Petrography of Igneous Rocks, Vol. 3, University of Chicago P~ess, Chicago, IL

- 1939 A Dercriptiut: Petrography of lgneous Rocks Vol 4, University of Chicago Press, Chicago, IL

JOHNSTON R H 1959 Geology of the Northern Lencite Hills, Sweetwater County, Wyoming M . A . Theris, University of Wyoming, Laramie, WY (unpub- lished)

JONES, A. P & SMIIH, J V 1983 Petrological significance of mineral chemistry in the Agathla Peak and the Thumb minettes, Navajo volcanic field J Geol. 91,647-56

- & -- 1985 Phiogopite and associated minerals from Permian minettes in Devon, S England Bull Geol Soc Finland, 57,89-102

JOPLIN, G A 1965 The problem of the potash-rich basaltic rocks Mineral Mag 34,266-75 - 1968 'The shoshonite as so cia ti or^: a review I Geol Soc Ailst 15,275-94

KAPLAN, G , FAURE, D , ELLOY, R & HEILAMMER, R 1967 Contribution Q l'ttude de l'origine des lamproites Bull Centre Rech PA V'SNPA, 1, 1% 9.

KAY, R W & GASI, P W 1977 Therareearthcontent and origin of alkali-rich basalts J Geol 81, 65.3- 82

KAY, S. M , K ~ Y , R W , HANGAS, J 9: SNEDDEN, T 1978 Crustalxenolithsfrompotassiclavas,Leucite hills, Wyoming Geol Soc Am Absir Progm 7, 432

K ELLER, 1 1983 Potassic lavas in the orogenic volcanism of the Mediterranean aiea I Voic Geoth. Res 18, 321-35

KEMP, J F 1897 The Leucite Hills of Wyoming Geol Soc. Am BUN 8, 169-82.

---&KNIGHT, W C 1903 LeuciteHillsof Wyorning Geoi Soc Am Bull 14, 305-36

KENNEDY, G C. 1955 Some aspectsof theroleof watel in rock melts Geol Soc Am Spec Pap 62, 489- 507

KNIGHI, G.L. &LANDES,K K 1932 Kansaslaccoliths J Geol 40, 1-18

KNILL, D C 1969 i h e Permian igneous rocks of Devon Bull Geol Suru Gt Br 29,115-38

-- 1982 Permian volcanism in Southwestern Eng- land, In SUIHERIAND, D S (ed ) Igneour Rocks o/ the BritOh Isles, pp 729-32 Wiley, London

KNOPF,D 1970 Les Kimberliter etles Rocher Apparenter de Cored Ivoire Sodemi, Abidjan

KOGARKO, L N 1980 Significance of chemical bond polarity in the geochemistry of magmatism Geo- khimlya 9, 1?86-97

- , KRIGMAN, L D & SHARUDILO, N. S 1968 Experimental investigations of the eff'ect of the alkalinity of silicate melts on separation of fluorine into the gas phase. Geokhqya 8,948-56

KOSIY~IK, V P 1983 The potassic alkalic magmatism of the Barkal Aldan Belt Sou Geol Geophys 24, 31-38

KRAMERS, J D , RODDICK, J C M & DAWSON, J B 1983 Trace element and isotope studies on veined, metasomatic and "MARID" xenoliths from Bnlt- ibntein, S Africa Earth planet Sci Lett 65, 90~- 106

KRANCK, E 1953 Bedrock geology of the seaboard of Labrador between Domino and Hopedale Bull Can Geol Suru. 26

KRAVCHENKO, S M , VLASOVA, E V. & PINEVICH, V. S 1960 Batisite, a new mineral, Dokl Akad Nauk S S S R 133, 657-8

KRESIEN, P , PRINIZLAU, I . , REX, D , VARIIAINEN, H. & WOOLLEY, A 1977 New agesof carbonaticand alkaline ultramafic rocks from Sweden and Fin- land Geol FurenStockh Forh 99, 62-65.

KRUMMENACHER, D & EVERNDEN, J F 1960 D6te1- mination d'ige isotopique fautes sur quelques roches des Alpes par le m&thode K-Ar Schweiz Mineral Petrogr. Mitt 40,267-77

KUEHNER, S M. 1980. Petrogenesis of ultrapotassic rocks, Leucite Hills, Wyoming M Sc Thesis, University of Western Ontario, London, Ontario (unpublished)

-. , EDGAR, A D & ARIMA, M 1981 Petrogenesis of the ultrapotassic rocks from the Leucite Hills, Wyoming Am Mlneral 66,663-7

KUSHIRO, I & AOKI, K 1968 Origin of some eclogite inclusions in kimberiite. Am Mmeral 53,1747--67

KYSER, T K , 0 NEIL, 1 R & CARMICHAEL, I S E 1981 Oxygen isotope thermometry of basic lavas and mantle nodules Contrib Mineral Petrol 77, 11-23 -- , & - 1982 Genetic relations among basic

lavas and ultramafic nodules: Evidence from oxygen isotope compositions Contrib Mineral Petrol 81, 88-102

LACROXX, A 1926 La systkmatique des ioches leuci- tiques: les types de la famille syenitique C R Acad Sci Paris 182, 597--601

- 193)a Contribution Q la connaissance de la composition chimique et mineralogique des roches eru~tives de I'Indochine BUN Seru Grol Indo- chine. 20, 3, 1-208

- 1977b Lesroches&ruptivespotassiquesleucitiq~~es ou non du Tonkin occidental C R Acud Sci Parir 197, 625-7

LANGFORD, R E 1973 A study of the orrgln of Arkansas diamonds by mass spectrometry PhD Thesis, university o f ~ i o r g i a , ~ i h e n s , ~ ~ ( u n p u b - lished)

LANGWORIHY, A P &BLACK, L P 1978 The Mordor complex: a highly diiierentiated potassic intrusion with kimberlitic affinities in central Australia Contrib Mrnrral Petrol 67, 51-62

LARSEN E S 1940 Petrographic province of central Montana Geol Soc. Am BUN 51,887-948

-- , HURLBUI, C S , BURGESS, C H & BUIE, B. F 1941 Igneous rocks of Highwood Mountains, Montana Geol Soc Am Bull 52,1857-68

L,ARSZN, L M , REX, D C & SECHER, K 1983 Age Of

carbonatites, kimberlites and lamprophyres from southern W Greenland: recurrent alkaline rnag- matism during 2500 million years L.~thor 16, 215- e , L1

LARSEN, W N 1954 Precambrian geology of the W Uinta Mountains, Utah, M S Therir, University of Utah, Salt L,ake City, UT (unpublished)

LASSERRE, J L 1976 Amphibolites and alkaline gneisses in the midland tbrmations of Nepal; petrography, geochemistry-geodynamic involve- ments. In : Je:;r, C (ed ) Himalaya sciencer de la rerre, Fr Cenr Natl Rech Sci , Colloq Int 268, 2, 21'3-36

LEES, G J 1974 Petrochemistry of the mica lampro- phyres (minettes) of Jersey (CI) Proc Lirrher Soc 3, 149-55

LEMAIIRE, R W 1976 The chemical variability of some common igneous rocks 1 Petrol 17, 589- 637

LEWIS, H C 1887 On a diamondiferous peiidotite and the genesis of the diamond Geol Mag 4,22-4

LEwn, P H 1973 Mica pyro.xenire mclusionr in lirrlburgite Hopi Butter Volcanic field Arizona unpubl M Sci Thesis, Brigham Young IJniv , lltah

LEWIS, R D 1977 Mineralogy, petrology and geophys- ical aspects of Prairie, Creek kimberlite, near Mur freesboro, Arkansas. M 5 Therii, Depart-. ment of Geoloay, Purdue University (unpub- .. lished) , MEYER, H 0 A ,BOLIVAR, S L. & BROOKINS, D B 1976. Mineralogy of the diamond bearing "kimberlite", Murfreesboro, Arkansas EOS 57, 761 (abstract only)

LIBBY, S C 1975 Origin of K-ultramafic rocks in the Enoree 'vermiculite' districts, S Carolina PhD Thesir, Pennsylvania State University (unpub- lished).

LLOYD, F E , ARIMA, M & EDGAR, A D 1985 Partial melting of a phlogopite clinopyroxenite nodule from south-west Uganda: an experimental study bearing on the originoi'highly potassiccontinental rift volcanics Cbntrib Mineral Perrol 91, 321-9

LOPEZ RUIZ, J & RODRIGIJEL BADIOLA, E 1980 La region volcanica Neogena del Sureste de Espana Errild Geol 36, 5-63

LOVE, J D , WEIIZ, J L & flOSE, R K 1955, Geological map of Wyoming (1/500,000 scale) U S deol surv-, Washington.

LUHR. J F & CARMICHAEL. I S E 1980. The Colima volcaniccomplex, Mexico1 Post calderaandesites from Volcan Colirna Contrib Mineral Petrol '71, 343-'72

-. & -- 1981 The Colima volcanic complex, Mexico: I1 Late Quaternary cinder cones Contrib Mineral Pefrol '76, 127-47

L.u'IH, W . C 1967 Studies in the system KAlSi0,- Mg,SiO,-Si02-H1O I : Inferred phase relations

and petrologic applications i Peffol 8, 372- 416

M ~ c D o w E r r , F W 1966 Potdssium-Argon dating 01 Cordilleran intrusives PhD Theru, Columbia University, New York (unpublished)

M&CANDLESS,T E 1982 The mineralogy, morphology and chemistry of detrital minerals of a kimberlitic and eclogitic nature, Green River Basin, Wyo- ming M S Theiir University of iltah, Salt Lake City, UT'(unpub1ished)

- 1984 Detrital minerals of mantle origin in Green River Basin, Wyoming Soc Min E'ng AIME, Preprint 84-395.

MCCLIJRE, W C 1963 Geology of the Enoree area: S Carolina M S c Thesis, University of South Caro- lina, Columbia, SC (unpublished).

M c C u r r o c ~ , M. T , JAQUES, A I. , NELSON, D R & LEWIS, J D 1983a Nd and SI isotopes in kimberlites and lamproites iiom W Australia: an enriched mantle origin Nature, Lond 302, 400-3

- , NELSON, D R., .TAQUES, A L & LEWIS, J D 1983b Nd and Sr isotopic systematics in kimber., lites and lamproites from West Kimberley, West- ern Australia Proc 6th Geological Society of Aurtralia Conu , Val. 9, pp 287-8 Geological Society of Australia, Sydney

MCKIE, 0 1966 Fenitization In TUSILE, C F & GIIIINS, J (eds) Carbonatrres, pp 261-94 Wiley- Interscience, New York

MADIGAN, R 1983 Diamond exploration in Australia Indmqua, 35, 2'7-38

MAKHERJEE, K K 1961 Petrology of lamprophyies of the Bokaro coalfield Qr I Geol Min Mefall Soc India 33,69-87

MAKSIMOV, E P 1982 The Mesozoic magmatism of the Aldan shield as an indicator of its tectonic regime. Sou Geol. Geophyr 23,9-14

MANSON, V 1967 Geochemistry of basaltic rocks: major elements In HESS, I I It3 , & POLDERVAARI, A (eds)Baralts Wiley, New York, 215-70

MARINELLI, G & MIIIEMPERGHER, M. 1966 On the genesis of some magmas of typical Medite1.ranea.n (potassic) suite. Bull Volcano1 29, 11 3-40

MARTHUR, S M & SINGH, H N 1971 Petrology of the Majgawan pipe sock: Geol Suru India hfirc Pub1 19,78-85,

MARVIN, R F,, HEARN, B C , JR., MEHNERI, H H , NAESER, C W , ZARTMAN, R E & L.INDSEY, D A 1980 late Cretaceous-Paleocene igneous activity in north-central Montana Irochron/Wesr 29, 5- L J

MASON, B 1967 Meteorites Am S C I 55,429-55 - 1977 Elemental distribution in minerals from the

Wolgidee Hills intrusion, Western Australia N Z DSIR B~ll l 218,114-20

- 1979. Cosmochemistry, Part I, Meteorites Pro/ Pap U S G S 440B-I

MAISON, R E 1960 Petrography and petrology of Smoky Butte Intrusives, Garfield County Mon- tana M S therzr Montana State University, Missoula, M I (unpublished)

ME4XINS. A 1987 Geology and genesis of the Argyle alluvial diamond deposits, Kimberley region, W Australia In DAVY R , BUSIE, C. R M &

Lamproztes and K

BALLINGER, 1 A (eds) Geochemical Exploratron in Arid and Deeply Weathered Environments Geo- chemistry and Genesis of Ore Deposits Associated with Weathering, Aust Reg Meet, Assoc Expi Geochem Perth, Abstracts volume 54-6

MELION, C E & GIARDINI, A A 1976 Experimental evidence that oxygen is the principal impurity in natural diamond Nature Lond 263, 309.- 10 - & -- 1980 The isotopic composition of Ar

included in an Arkansas diamond and its signifi- cance Geophp~ Rer Lett 7,461-4 - , Salotti, C A & GIARDINI, A. A 1972 The

observation of N,, H 2 0 , CO,, CH, and Ar as impurities in natural diamonds Am Mineral 57, 1518-23

MENZIEs, M & MURIHY, V R 1980a Enriched mantle: Nd and Sr isotopes in diopsides from kimberlite nodules Nature L,ond 283, 6:34-6

-- & 1980b Nd and Sr isotope ~eochemistry of hydrous mantle nodules and their host alkali basalts: implications for local heterogeneities in metasomatically veined mantle Earth planer Sci Lett 46, 323-34

MERRILL, R B., BICKFORD, M E & IRVING, A 1 1977 TheHills Pond Peridotite, Woodson County, Kansas: A ricbterite-bearing Cretaceous intrusive with kimberlitic affinities Extended Abrtr 2nd Kzmberlite Conf 5anta Fe NM

MESEGUER PARDO, 7 1924 Estudio de 10s yacimlentos de azufre de las provincias de Murcia y Albacete Bol Inst Geol E:rp 45, 1'31-214

MEYER, H O A 1976 Kimberlites of the continental United States: a review I. Geol 84,377-403

- & MIICHELI, R H 1985 Sapphire-bearing lamprophyre from Yogo Gulch, Montana Geol Asroc Can progm abrtr 10, A39.

- , LEWIS, R D , BOLIVAR, S & BROOKINS, D G 1977 Prairie Creek Kimberlite, Murfreesboro, Pike County, Arkansas. Extended Abrtr 2nd Int Kimberllte Conf: Sonia Fe, NM

MIDDLEMOSI, E. A K 1975 The basalt clan Earth 5cr Rev 11, 337-64

MILLER J A & M o m , P A 1964 K-Ar measurements on the granites and some associated rocks from Southwest England Geol I Liverpool 4, 105-26

MILLER, K C 1982 Paleornagnetism of Indian Kimberlites B A Them, Princeton University, Princeton, NJ (unpublished)

MILLER, T P 19'70. Petrology of the plutonic rocks of west-central Alaska U 5 Geol SLOO Open File Rep. 545 1972 Potassium-rich alkaline inttusive rocks of

Western Alaska Geol Soc Amer BUN 83. 21 11- 28.

MINEYEVA, I G 1972 Principal geochemical charac- teristics of potassic alkalic rocks Geochem Inr 9,

-rzch zgneou, rocks 183

the leucite lamproites of the W Kimberley Area, W. Australia Contrib Mineral Petrol '76,243-51

- 1985 A review of the mineralogy of lamproites Trans Geol So(. SA 88,411-437

- &BELL, K 1976 Rare earthelement geochemistgv of potassic lavas from the Birunga and Tolo.. Ankole regions of Uganda. Africa Contrib Min- eral. ~ e t r o T 58,293-63 - & HAWKESWGRTH. C J 1984 Geochemistrv of potassrc lavas from Smoky Butte, Montana Geol SOL Am Abrtr Progm 16,597

- & Lewis, R D 1983 Pndertte-bearing xenoliths from the Prairle Creek mlca per~dotlte, Arkansas Can Mineral 21, 59-64

MOD RE SKI,^ J &BOEI?CHER,A L 1972 Thestability of phloaooite + enstatite at high pressurei: a model f o r micas in the inte~ior of tihe earth Am 7 Scr 272, 852-69

- & - 1973 Phase relationships of phlogopite in the system K,O-MgO-CaO--A1,0,-Si0,-H,O to 35 kilobars: a better model for micas in the interior of the earth Am. J Sci 273, 385%414

MOODY, C L. 1949 Mesozoic igneous rocks ot Northern Gulf Coastplain,Bull Am Arroc Petrol Geol 33, 1410-28

MORRIS, E C. 1953 Geology of the Big Piney area, Summit County, Utah M S Thexi?, University of Utah, Salt Lake City, IJT (unpublished)

MORRISON, G W 1980 Characteristics anstectonic setting of the shoshonite rock association Lithor, 13.97- 108

MULLEN, E D & MURPHY, S 1985 Mmeralogy and petrology of lamprophyric and carbonatite dikes, centralArkansas Geol Soc Am Abrtr Proam 17. "

185. -- & PEIIY, W B 1985 Petrologic relations among

syenites and lamprophyric rocks, Arkansas alkalic Province Geol.Arsoc Can Progm Abrt? 10, A42

MIIRIY, M K 1980 Tectonics and geochemistry of the diamondiferous kimberlites of the Jungle Valley, Merzapur District, U P -an evolutionary model. Proc C'onf onD~amonds GeologicalSurvey of India, Bombay

MURIY, Y G K , RAO, M. G., MISRA, R C & ,4111 K~JMAR REDDY, T 1980 Kimberlite diatremes of Andhra Pradesh-their assessment and search for concealed bodies Prof Conf onDiamondr, Geolog. ical Survey of India, Bombay

MUICEILER, E. E , ROUGHON, D 1 & LAVIN, O P 1976 PETROS: a data bank of major-.element chemical analyses of igneous rocks for research and teaching Comput Geol. Sci 2, 51-7

MYSEN B O & BOEI.ICIIER, A L , 197% Melting of a hydrous mantle: I Phase relations of natural peridotite at high pressures and temperatures with controlled activities of water, carbon dioxide, and

173-9 hydrogen J . Petrol 16, 520-48 MISER, N D & PURDUE, A H 1929 Geology of the - &- 1975b Melting of a hydrous mantle: I1

De Queen and Caddo Gap quandrangle, Arkansas Geochemistry of crystals and liquids formed by U 5 Geol Survey Bull 808, 195 anatexis of mantle peridotite at high pressures and

- & Ross, C: S 1920 Diamond-bearing peridotite high temperatures as a function of controlled in Pike County, Arkansas U 5 Geol Suruey BUN activities of water. hvdrogen, and carbon dioxide , - 735-1,279-32-2 J Petrol 16, 549-93

MIICHEIL, R H 1981 Titanrferous phlogop~tes from NELSON, D R , MCCUILOCH, M I &SUN, S -S 1986

1 84 S C B

The origins of ultrapotassic rocks as inferred irom Sr, Nd and Pb isotopes Geochim cormochim Acta 50,23 1-46.

N ~ M E C , D 1972 Micas of the lamprophyres of the Bohemian Massif Neuer Jb Mineral Abh 117, 196-216

-- 1973 Amphibole der lamprophyrischen und lamproiden Gestine in Ostfeil der Bohmischen Masse Car hfineral Geol 18, 31-46

- 1974 Petrochemistry of the dyke rocks of the Central Bohemian Pluton Neuer J Mineral Monntrh 193-209

- 1985 Ba and its carriers in dvke rocks of the minette serizs Geol Arroc Cdnada Progm Abrtr 10, A43.

NICH~LLS, J & CARMICHAEL, I S E 1972 The equilibrium temperature and 'pressure of various lava types with spinel. and garnet-peridotites Am Mineral 57,911-59

NIELSEN, B L , 1976 Economic minerals diamonds, olivine, garnets in Greenland In ESCHER, A & WAII, W. S (eds) Geology ojGreenIand, pp 481- 6 Geological Survey of Greenland, Copenhagen

N I G G L I , ~ 1921 Gesreinr-icndMinera1provrnzen Gebru- der Borntraeger, Berlin

NIXON, P H , THIRWALL, M F & BUCKLEY F 1982 Kimberlite-lamproite consanguinity T e r ~ a Cog- nita 2, 252-54

---. -- & DAVIES, C J 1984 Spanish and Western Australian lamproites: aspects of' whole rock geochemistry i n : KORNPROBST, I. (ed) Kimberlites I : Kimberlites and Related Rocks, pp 285-96 Elsevier, Amsterdam

NOBEL, I; A , ANDRIESSEN, P A M , HEBEDA, E H PRIEM, H N A & RONDEEL, H E 1981 Isotopic dating of the post.Alpine Neogene volcanism in the Betic Cordilleras, southern Spain Geol Monbouw 60,209-14

NOCKOLDS, S R 1940 Petrology of rocks from Queen Mary Land Azrrtralian Antarctic E,~pedztion 1911- 14,'Rep Ser A IV, Part 2, pp 15-86

-. 1954 Average chemical composition of some igneous rocks Geol SOL Am BziN 65, 1007-32

NOE-NYGAARD, A & RAMBERG, H 1956 Geological reconnaisance map of the country between lati- tudes 69"N and 63"45'N, West-Greenland, (1/500,000 scale) Geological Survey of Greenland, Copenhagen & - 1961 Geological reconnaissance map of

the country between latitudes 69"N and 63"45'N, W Greenland Meddr Gronland 123, 3

NORRISH, K 1951 P~iderite, a new mineral from the leucite-lamproites of the West Kimberley area, Western Australia Mineral Mag 24, 496-501

NOUGIER, J 1970 Contribution i l'htude gkologique et ghomorphologique des iles Kerguelen (Territoire des Teires Australes et Antarctiques Fran~aises) Corn Natl Fr Rech Anrarct 27,696 pp

O'BRIEN, H E ,IRVING, A. J & MCCAILUM, I S 1985 Complex zoning of ciinopyroxene in shonkinites and mafic phonolites, Highwood iMtns Montana: evidence 1'01 periodic mixing with a K.rich basa- nitic magma Geol Sac Am Ab,rtr P ~ o g m 17, 187

OGDEN, P R , Js 1979 I h e geology, major element geochemistry and petrogenesis of the Leucite Hills volcanic rocks, Wyoming PhD The,rzr, University of Wyoming, Laramie, WY (unpublished) , ~ P E R F \ , J 7 , GUNIER, W D & PAJARI, G E , TR. 1978 Morphology of a recent ultrapotassic volcanic field, Leucite Hills, SW Wyoming Geol Sac Am Abstr Progm 10, 140 , VOLLMER, R & SCHILLING, J G 1980 Leucite Hills revisited EOS 61, 412

OSANN, A 1889 Beitrage Zue Kentniss der Eruptive- gesteine des Cabo de Gata I Z dch Geol Ger 41, 297-3 11 - 1906 Uber einrge Alkaligerrzne arrr Spanien

Festchritte, Rosenbusch, Stuttgart OSBORNE, F F & ROBERIS, E J 1931 Differentiation

in the Shonkin Sag laccolith, Montana Am J 5'1 5th set 22. 331-53

OWENH G 1983 Atlay ~Jcontinentnldi~placemen~ 200 million yearr to thepresent Cambridge Univ Press, Cambridge

OYAWOYE, M 0 1976 The origin and evolution of the potassic rocks of SW Nigeria 2.5 Int Geological Congr Abrtr Vol 21,10A, pp 424-5

PAGEL, M & LEIERRIER, 7 1980. The subalkaline potassic magmatism of the Ballous Massif (S Vosges, France); shoshonitic affinity L.ithor 13, 1- ~n A"

PAROA PONDAL, 1 1935 Quisismo de las manifesta- ciones magmaticas Cenozoicas de la Peninsula lberica Trah Mur Nac C Nar Se? Geol 39

PAUL, D K , REX, D C & HARRIS, P G 1975 Chemical characteristics and K-AI ages of Indian kimberlites Geol Sac A m Bull 86,364-6

PELLICER, M J 1973 The petrology and geochemistry of new lamproite rocks near Aljorra, Murcia, Spain Eustud Geol Init invert Geol Lucar ~fal lade. 29,99-106

PHILLIPI, E 1912 Geologische Beschreibung des Gassbergs Deutsche Siidpolar Expedition 1901- 1903 Geogr Geol 11,47-71.

PIRSSON, L V 1905 Petiography and geology of the igneous rocks oi the Highwood Mountains, Mon- tana Bull U S Geol SLOU Bull 237

POLANSKI, A 1949 The alkaline rocks of the East- European Plateau Bull Soc Amzr Sci Lett Poznan Ser B 10,119-84

POLDERVAARI,A I955 Chemistry of the Earth'scrust Geol SOL Am Spec Pap 62, 119-44

Powsrr , J L & BELL, K 1970 Strontium isotopic studies of alkalic socks Localities from Australia, Spain, and the Western United States Contrzb Mineral Petrol 27, 1-10

- & - 1974 Isotopic composition of Sr in alkalic rocks In SORENSEN, H (ed ) Ttie Alkaline Rockr, pp412-21 Wiley, New York

PRIoeR, R T 19.39 Some minerals from the leucite- rich rocks of the West Kimberley area, Western Australia Mineral Mag 25, 173-87.

- 1960 The leucite lamproites of the Fitzroy Basin, Western Australia. J Geol SOL 4urt 6: 71-1 18

- 1965 Noonkanbahite, a potassic barisire irom the lamproites of Western Australia mineral Mag 34,403-5

- 1982 Aglassy lamproite from the West Kimberiey area, Western Australia Mineral Mag 45, 279- 82

-- & COLE, W F 1942 the alteration products of olivine and leucite in the leucite-lamproites from the West Kimberley area, Western Australia Am mineral 27,373-84

PRIMAL, L 1963 Etude gkologique et mt-tallogt-nique de la partie m&ridional du cap Corse PhD Therir, University of Paris (unpublished)

PROSIKA, H J 1973 Hybrid origin of the absarokite- shoshonite-banakite series, Absaroka volcanic field, Wyoming Geol Soc Am BUN 84,697-702,

PRYCE, M W , HODGE, L C & CRIDDLE, A J 1984 leppeite, a new K-Ba-Fe titanate from Walgidee Hills, Western Australia Mineral Mag 48, 261- 6

RADULESCU, D P 1966 Rhyolites and secondary ultrapotassic rock:; in the subsequent Neogene volcanism from the E Carpathians BUN Volcano1 29, 425-34

RAVICH, M G & KRYIOV, A H 1964 Absolute ages of rocks from E Antarctica In ADIE, R 1 (ed.) Antarcrrc Geology pp 578-89 North-Holland, Amsterdam

REINISCH, R 1912 Petrographische-Beschreibungder Gaussberg-Gesteins Deutsch Siidpolar..Expedi. tion 1901-03 Geogr Geol 11,73-8

RIOU, R , DUPUY, C &DOSIAL, T 1981 Geochemistry of co-existing alkaline and calc-alkaline volcanic rocks from Northern Azerbaijan (N W Iran) J Volc Geoth, Res. 11, 253-75

RII.IMANN. A 1933 Die eeoloeisch bedinete Evolution - " - und Differentiation des Somma-Vesuvius magma Z Vukanol 5,s-94

- 1951 Magmatic character and tectonic position of the Indonesian volcanoes Nomenclature of volcanic rocks Bull. Vol~.anol 12, 75-109

ROBINS, B , FURNES, H & RYAN, P 1981 A new occurrence of dalyite Mineral Mag 47,93-4

R o s l ~ s o ~ , E- C 1976 Geochemistry of lamprophyric locks of the eastern Ouachita Mtns, Arkansas M S . Thesis. IJniversit~ of Arkansas, Favetteville, . . AR (unpublished)

ROCK, N M S 1976 The comparative Sr isotopic comoosition of alkaline rocks: new data fiom south Portugal and East ~ f r i c a Contrib Mineral Petrol 56,205-28

- 1977 The nature and origin of lamprophyres: some definitions, distinctions and derivations Earth Sci Reo 13, 121-69

-- 1984 Nature and origin of calc-alkaline lampro- phyres: minettes, vogesites, kersantites, spessar- tites Tranr R Soc Edinburgh 74, 193-227

- 1986 The nature and origin of lamprophyres: alnoites and allied rocks (ultramafic lampro. phyres) J Petrol 27, 155-96

- 1987 The nature and origin of lamprophyres: an overview In F1rroi.i. 1 G & UFION, B G J (eds).Alkaline Igneour Rockr Geol Soc Spec Publ 30, pp 191-226

RODEN, M F 1981 Origin of coexisting minette and ultramafic breccia, Navajo volcanic field Conrrib Mineral Petrol 77, 195-206

-rzch igneous rocks 185

- , SMIIH, D & MCDOWELI, F W 1979 Age and extent of potassic volcanism on the Colorado Plateau Earthplanet Sci Lett 43,279-84

ROEDDER, E 1984 Fluid inclusions Rev Mtneral 12, S06-511

ROGERS, N W BACHINSKI, S W HENDERSON, P & PARRY, S J 1982 Origin of potash-rich basic lamprophyres; trace element data fiom Arizona minettes Earthplaner Sci Lett 5'7, 305-12 - , HAWKESWORTII, C 1 , PARKER, R 1 & MARSH,

J. S 1985 The geochemistry of potassic lavas tiom Vulsini, central Italy and implications for mantle enrichment processes beneath the Roman region Contrib. Mineral Petrol 90, 244-57

RONOV, A B & YAROSHEYSKY, A A 1969 Chemical composition of the Earth's Crust Am Geophyr Unron Monogr 13, 77-57

ROSENBUSCH, H 1877 Mikrorkopirchr Phyrzographze, 1st edn Schweizerbart, Stuttgart

-. 1887 Mikrorkoprrche Phyriograpie, 2nd edn Schweizerbart, Stuttgart

Rosi, M 1980 'The island of Stromboli Soc Ira1 Mineral Petrol Rend 36, 345--68

Ross, C P , ANDREWS, D A & WIIKIND, I J 1955 Geological map of ' Montana (1/500;000 scale) Montana Bureau of Mines and Geology, Helena

Ross, C S 1926a Nephelite-hauynite alnoite from Winnett Montana Am J Sci 11,218-27 1926b A Coloradolamprophyreoftheverite type, Am J SCI . 12,217-29 , MISER, H O & SIEPHENSON, L W 1929 Water laid volcanic rocks of early Upper Cretaceous age in SW Arkansas, SE Oklahoma and NE Texas U S Geol Surv Prof Pap 154F, 175-202.

ROWELL, W F. & EDGAR, A D 1983. Cenozoic potassium-rich mafic volcanism in the western U S.A : its relationshio to deep subduction J Geol 91,338-41

ROY, B C 1962 Geological Map of India (1/5,000,000 scale) Geol Surv India

ROY CHAUDHURY, M K 1973 Geological and mineral map of Andhra Pradesh (1/2,250,000 scale) Geol Surv I n d ~ a

RUDDOCK, D I &HAMILTON, D I 1978a Stab~lrty of carbonate in a slmple potasslum-rich rock model Prog Exp Petrol NERC Publ Ser D 11, 7.8- " 3 > I

- & -- 1978b The system KAISi,O,-CaMg Si,O,-SiO,at4 kb Prop E X D Petrol NERCPubl " . sei b i i , i5-27

RYABCHIKOV, I D & BOEIICHER, A L 1981 Experi- mental evidence at high pressure for potassic metasomatism in the mantle of the earth Am Mineral 65, 91 5-9 & GREEN, D H 1978 The role of CO, in the

petrogenesis of highly potassic magmas Tr. Inrt Geol Geojz Akad Nauk S S S.R No 403,49-64 - , SCHREYER, W & ABRAHAM, K 198% Composi-

tion of aqueous fluids in equilibrium with pyrox- enes and olivines at mantle pressures and temperatures Conrrrb Mineral Petrol 79, 80-4

SAEIHER, E 1950 On the genesis of peralkaline rock provinces. 18th Int Geology Congr London Part 11, pp 123-30

SAHAMA, T h G 1974 Potassium-rich alkaline' rocks In S~RENSEN, H (ed ) The Alkaline Rockr, pp 96- 109, Wiley London

SALTERS, V. J M , & BARTON, M 1985 The geochem- istry of ultrapotassic lavas from The Leucite Hills, Wyoming EOS: 66, 1109

SAN MIGIJEL DE L A CAMERA, M 1935 Una erupcionde jumillita en la Sierra de las Cahras (Alhacete) Bol R Soc Esp ,?Hist Nat 35, 147-54

- , ALMELA, A 81 FIJS'IER, J M 1952 sobre un volcan de veritas recientemente descuhierto en el Miocene de Barqueros (Murcia) Ertud Geol 7, 41 1--29.

SANYAL, S P 1964 Petrology of certain lamprophyres from the Jharia Coalfield Bihar, with a discussion on the differenttiation of the Sudamdih Sill Mirc Pub1 Geol Si~ro India. 8,27-44

SARKAR, A , PAUL, D K., BALASUBRAHMANYAN, M N a SENGUPIA. N R 1980 Lamprophyres from Indian Gondwanas; K-Ar ages and chemistry I Geoi. Soc India, 21, 188-93

SARMA, B S P i983 A report on ground magnetic survey over Chelima dyke (Cuddapah basin) Not Geophyr Res Inrt H~derabad Indra Tech Rep 83-210

SAIHE, R V & S S 1975 Petrogenesisof lamprophyxes of Mt Girnar, Saurahtsa Q 1 Geol Min Metal1 Soc India, 46, 61-7

SAIYANARAYANA RAO, P & PHADIRE, P N 1966 Kimberlite pipe rocks of Wajrakarur Area, Anan. tapur district, Andhra Pradesh I Geol Soc India 7.118-23,

SCHAIRER, J F & BOWEN, N L 1938. The system 1eucite.diopside-silica Am i Sci 235-A, 289-309

SCHEURING, B , AHRENDI, H , H U ~ I K E R , J. C & ZINGG, A 1974 Paleohotanical and Geochronol- ogical evidence fbs the Alpine Age of the met* m o r ~ h i s m in the Sesia Zone Geol Rundrch 63, 305-26

SCHMIII, H. H , SWANN, G A & SMIIH, D 1974 The Buell Park kimherlite pipe, N E. Arizona In: KARLSIRUM, T , SWANN, G A & EASIWOOD, R L (eds) Geology ofivorthern Arrrona, pp 672-98 Northern Arizona Univ , Flagstaff

SCHNEIDER, M E 1982 Major element compositions of silicates dissolved in supercritical fluids at mantle conditions: implications f o r mantle meta. somatism M S Thesis Pennsylvania State Uni- versity (unpublished)

- & EGGLER. D N 1984 Com~ositions of fluids in ~~ -~~

equilibiium with peridotite: implications for al- kaline magmatism-metasomatism In: KORN- PROLSI, J (ed) K~mberliler I Kimberlites and Related Rockr, pp 383-94 Elsevier, Amsterdam

SCHULIZ, A R & CROSS, W 1912 Potash-hearing rocks of the L.eucite Hills, Sweetwater County, Wyoming U S Geol Suru Bull 512, 1-39

SCHULZE, D J & HELMSIAEDI, H 1979 Garnet pyroxeniteand eclogite xenolithsfrom theSullivan Buttes latite, Chino Valley, Arizona I n BOYD, F R & MEYER, H 0. A (eds) The mantle rampie Inclusions in kimberlites and other volcanzcs Proc .?nd Int Kimberlite Con! Vol. 2 pp 318-29 American Geophysical Union, Washington, DC

- , SMI.IH J V , & NBMEC, D 1985 Mica chemistry of lamprophyres from the Bohemian Massif, Czechoslovakia iVeues Iahrb Mineral Ahh 152, 321-34

Scor i , B FT 1977 Petrogenesis of kimberlites and associated potassic lamprophyres from central West Greenland PhD Thesis University of Edin- burgh (unpublished)

- , 1979 Petrogenesis of kimberlites and associated potassic lamprophyres from central West Green- land In: BOYD, H R & MBYER, H O A (eds) Kimberlites Diatremes and Diamonds Their Geol.. ogy Petrology and Geochemirtry Proc 2nd In1 Kimberlite Conj , Vol. I , pp 190-205 American Geophysical Union, Washington, DC

- 1981 Kimberlite and lamproite dykes from Holsteinsborg, W Greenland Meddr Granland, 4, 3-24

SCOTI..S~IIIH, B H &SKINNER, E M W 1982 A new look at Prairie Creek, Arkansas Terra Cognita, 2, 210

-- &- 1984a A new look at Prairie Creek, Ar kansas In: KORNPROBSI, J (ed ) Kiniberlites I Kimberlites and Related Rockr, pp 255-84 Elsev- ier, Amsterdam &- 1984h Diamondiferous lamproites I

Geol 92,433-8 -. & - 1984c Klmberlite and American Mines

~ ~

near Prairie Creek Arkansas In: KORNPROBSI, J (ed ) Kimberlites 111: Documents Ann Sci Univ Clermont-Ferrand I1 74, 27-36

SCULL, B J 1959 'The age of mineralization in the Ouachita Mountains of Arkansas and Oklahoma Symp. on the Geology of the Ozrachita Mounrainr, pp 62-9 Dallas Geological Society and Ardmore Geological Society

SEARLE, M P 1984 Alkaline peridotite pyroxenite and gabbroic intrusions in the Oman Mountains, Arabia Can I Earth Sci 21, 396-406

SEN, S N & NARASHIMA RAO 1970. Chelima dykes Proc 2nd Symp on Upper Mantle Project Session .5, Combined Georuruey$ in Dharwar and Cltddapah Barin Hyderabad India, pp 435-9

SHAFIQULLAH, M , DAMON, P E & L.YNCH, D J 1976 Ultrapotassic trachytes at Pichaco Peak in the southern Basin and Range province, Arizona Geol Soc Am Abstr Progm 8,628

SHAND, S 1 1927 Eruptive Rocks, 1st edn Thomas Murby, London

.- 1971 ?he granite-syenite-limestone complex of Palahora Transvaal Trans Geol Soc 5 Afr 67, 81-92

SHERAION, J W 1983 Geochemistry of mafic igneous rocks 01 the norther11 Prince Charles Mountains, Antarctica i Geoi Soc Aurt. 30,295-300

-- & CUNDARI, A 1980 Leucitites from Gaussberg, Antarctica Contr~b Mineral Petrol '71,417-27 - & ENGLAND, R N I980 Highly potassic mafic

dykesfrom Antarctica 1 Geol Soc .lust 27, 129- 35

- , OFFE L A , TINGEY, R J & ELLIS, D J 1980 Enderhyland, 4ntarctica-anunusualPrecamhrlan h~gh-grade metamorphic terrain I Geol Soc Ausr 27, 1-18

Lamproltes and 1;

SIMPSON, E S 1925 Contributions to the mineralogy of Western Australia Series I J R Soc W Aurt 12,57-66

SKEAIS, E W & RICHARDS, H C 1926 Report of the alkaline rocks of Australia and New Zealand Committee Aurt Arroc Adv Sci 18,36-45

SKINNER, E M W & CLEMENI, C R 19'79 Mineral- ogical classification of Southern African kimber- lites In: BOYD, H R & MEYER, H 0 A (eds) Kimberliter Diatremes and Diamondr Their Geol- 0g.y Pet1olo8,v and Geochemirtry. Pro< 2nd Int Kimberlite Conf , Vol I, pp 129-39 American Geophysical Union, Washington, DC

- & Scor1, B H 1979. Petrography mineralogy and geochemistry of kimberlite and associated lamprophyre dykes near Swartruggens, W Trans- vaal, RSA. Kimberlrre Symp / I Cambridge

SMITH, C B 19838 Pb, Sr and Nd isotopic evidence for sources of Southern African Cretaceous kim. berlites Nature. Lond 304, 51-4

-- 1983b Rb-Sr, U-Pb and Sm-Nd isotopic studies of kimberlite and selected mantle-derived xeno. liths PhD Thesis, University of Witwaterstrand, Johannesburg (unpublished)

- 1984a The genesis of the diamond deposits of the West Kimberley, W A In: PURCEII, P G (ed) The Canning Basin W A Proc Geological Society of Australia and Petrology Exploration Society of Australia Symp , Perth, pp 463--74

- 1984b What i s a kimberlite? In : GLOVER, I E & HARRIS, P G. (eds) Kimberlite Oc<ur,ence and Origin aBasir for Conceprualhfodek inExploration Univ W Aortraha Pub1 8, pp 1-18

SMIIHSON, S B. 1959 The geology of the southeastern LeuciteHills,Sweetwater County, Wyoming M A therir, Univ Wyoming, Laramie (unpublished),

SMYIH, C. H MR 1927 The genesis of alkaline rocks, Am Phil Soc Proc 66, 535-80

SOBOLEV, V. S. 1970 On the genesis of leucite-bearing rocks Dokl Akad Nauk S S S R Earth SCI Sect, 194, 166-8 - , BAZAROVA, I J & YACI, K 1975 Crystallization

temperature of wyomingite tiom Leucite hills Conrrib Mineral Petrol 49, 101-8

S O ~ O V ~ E V , D A 1972 Platform magmatic formations of E:ast Antarctica In: ADIE, R. J (ed) Antarcrk Geolony and Geo~hyricr, DD 531-8 Tjniversitets- . . forlaiet, Oslo .

S~RENSEN, H 1960 On agpa~tlc rocks In OFIEDAHL, C & H J E ~ M Q V ~ ~ ~ , S (eds) Plot 2lrr Int Geol Congr ,Pa i t 13, Petrographrc Provincer, Igneour and Metamorphk Rockr, Det Berlingske Bogtrykkeri, Copenhagen pp 319-2 7

SIAUDICEL, H & ZINDIER, A 1978 Nd and Sr isotope compositions of potassic volcanics from the East Eifel, Germany: implications for mantle source regions Geol Soc Am Abstr Prog 10, 497

SIEELE,K F & WAGNER, G H 1979 Relationship of the Murfrecsboro kimberlite and other igneous rocks of Arkansas USA In: BOYD, H R & MEYER, H 0 A (eds) Kimberlner Diatremer and D~amondr Thezr Geology. Petrology and Geochem- irrry Pmc 2nd Int Kimberlite Con/, Voi I, pp

;-rich Igneous rocks I 8.7

393--9 American Geophysical Union, Nashing- ton, DC

SIEFANINI, G 1934 11 complesso eruttivo di orciatico e Montecatini inprovincia di Pisa Atti So< Torc Scr )Vat Mern 44, 224-300

SIEFANOVA, M & BOYADIIEVA, R 1975 On the geochemistry of Nb and ?a in K-alkaline lampro- itic rocks from the village of Svidnja, district of Sofia Geocham Min Petrol 1, 16-30,

SIEPHENSON, P J 1972 Geochemistry of some Heard Island igneous rocks I n : ADIE, R . J. (ed )Antarctic GeologyandGeophyricr,pp 793-801 Universitets- foriaget, Oslo

SIEWARI, D B 1979 The formation oi siliceous potassic glassy socks In: YODER, H S (ed) 'The Evolution o/ the Igneous Rockr 50th Anniversary Perrpecriver, pp 339-50 Princeton IJnive~sity Press, Princeton, N J

SIEWARI, 0 F 1949 Origin and occurrence of vermiculite at Tigerville, S Carolina MS Thesir, University of South Carolina, Columbia, SC (unpublished)

SIONE, C G & SIERIING, P J 1964 Relationship of igneous activity to mineral deposits in Arkansas SfateojArkansar-Ark Geol Con! LittleRock Ar

S I R ~ C K E , K J , FERCIJSON, J & BLACK, L P 1979 Structural setting of kimberlites in Southeastern Australia In: BOYD, H R & MEYER, H 0 A (eds) Kimberlirer Dratremer and Diamondr, Proc 2nd Kimberlite Conf., Vol 1, pp 71-91 Am Geophys Union, Washington

SIRECKEISEN, A 1967 Classification and nomenclature of igneous rocks-final report of an enquiry Neuer Jb Mineral Ahh 107, 144-214

-. 1980 Classification and nomenclature of volcanic rocks, carbonatites and melilitic rocks IUGS subcommission on the systematics of igneous rocks. Geol Rundrch 69, 194-207

SVISERO, D P HASUI, Y & DRIJMMOND, D 1979a Geologia de kimberlitos de Alto Paranaiba, Minas Gerais (Geology of kimberlites of the Upper Paranaiba, Minas Gerais). Min MetaeiaN. 42,34-38

- , MEYER, H 0 A & HSIAO-MINC TSAI 1979b Kimherlites in Brazil: an initial report In: BOYD, H . R & MEYER, H 0 A (eds) Kimberlites Diatremes and Diamondr . Therr Geology Pet?ology and Geochemirtry Proc 2nd Inr Kimherlire Conf , Vol I, pp 92-100 American Geophysical Union, Washington, DC

- , HARAIYI, N L E & H ~ S U I , Y 1984 A note on the geology of'some Brazilian kimberlites J Geol 92,731-8

TAPPE, J . 1966 The chemistry, petrology and structure of' the Big T'imher complex, Crazy Mountains, Montana PhD Thesis, Univ Cincinnatti (un- pub1 ).

TAYLOR, H P 1968 The oxygen isotope geochemist~y of igneous rocks Contr~b Minela1 Petrol 19, l - 7 1

-. , GIANEIII, B & TURI, B 1979 Oxygen isotope geochemistry of the potassic igneous rocks from the Roccamonfina volcano, Roman comagmatic region Earth planet. Sci Lett 46: 81-106

- &TURI, B 1976 High "0 igneous rocksfrom the

Tuscanmagmaticpsovince,Italy Contrrb ilIinera1 Petrol 55, 34-54

-. .- & CUNDARI, A 1984 r80/'60 and the chemical relationships in K-rich volcanic rocks from Australia, E Africa, Antarctica and San Venanzo, Cupaello, Italy Earth planet Sci Lett 69,267-76

TAYLOR, S R 1979 Lunar and terrestrial potassium and uranium abundances: implications of the fission hypothesis Proc 10th Lunar Sci Cord, 2017-30

- & MCLENNAN, S M 1981 The composition and evolution of the continental crust: rare earth element evidence from sedimentary rocks Phil Trans R Sac Lond A301, 381-405

TEMPLEMAWKLIJI;, D J . 1969 Re-examination of pseudoleucite from Spotted Fawn Creek, West Central Yukon. Can. J Earth Sci 6 , 55-62

TERZAGHI, R D 1935 The origin of the potash..rich rocks. Am I Sci 29,369.

THIBAUI, G , RAOIILCARUBA, M M. & TURCO, G 19'72 Etude expkrimentale du domaine de formation de la dalyite K,ZrSi,O,, et essai de corrklations pktrologiques. C' R , Acad. S c i Paris, 274, 792-5

THOENEN, J R , HILL, R S , HOWE, E G & RUNKE, S. M 1949 Investigation of the Prairie Creek diamond area, Pike County Arkansas U S Bur Mines Rep Inuesr 45-9

THOMPSON, R . N 1977 Primary basalts and magma genesis 111 Alban Hills, Roman Comagmatic province, central Italy Contrrb M~neral Pet101 60,91-108.

- 1985 Asthenospheric source of Ugandan ultra- potassic magma I Geol 93,603-5

.- , MORRISON, M A , HENDRY, G L &PARRY S J 1984 An assessment of the relative roles of crust and mantle in magma genesis: an elemental approach Phil Tranr R Soc Lond Ser A 310, 549--90

'THY, P 1982 Richterite--arfvedsonite-riebeckite-ac. tinolite assemblage from MARID dykesassociated with ultrapotassic magmatic activity in central West Greenland Terra Cognifa, 2,247-9 - 1985 Contrasting crystallization trends in ultra-

potassic lamproites from central W Greenland Geol A.sroc Canada Progm Abstr 10, A63

TIDMARSH, W G 1932 The Permian lavas of Devon Q 7 Geol Soc Land 88,712-3

TIKMONENKOV. I. P . KUKIIARCHIK, M V & PYAIENKO, Yu A 1960. Wadeite from the Khibiny Massif and the conditions of its formation Dokl Akad Nauk. 5 S S R. 134,920-.3

TINGEY, R J 1981. Geological investigations i,n Antarctica 1968-1969: The Pryce Bay-Amery Ice Shelf-Prince Charles Mountains area Aiist Bco Miner Resources Geol Geophyr Rep 1981134

-. ,MCDOUGALL,I &GLEADOW,A 1 W 1983 The age and mode of formation of Gaussberg, Antarc- tica. J geol. SOL. AUSI 30, 241-24

TRAII, D S. 1963 The 1961 geological reconnaissance in the Southern Prince Charles Mountains, Ant- arctica Rec Bur Miner Resourcer Geol Geophys ,lusr 1963-1 55 (unpublished)

TR~~GER, W E 1935 Spczielle pemozraphle der Elup.

tivgerteinr, Deutschen Mineralogischen Geseli- schaft, Berlin,

TRONNES, R G , EDGAR, A D & ARIMA, M 1985 A high pressure-high temperature study of TiO, solubility in Mg-rich phlogopite: implications to phlogopite chemistry Geochim cormochim Acta, 49,2323-9

TUREKIAN, K K & WEDEPOHL, K H 1961 Distribu- tion of the elements in some major units of the earth's crust Geol Soc. Am Bull 72, 1'75-91

T~JRI, B & TAYLOR, I3 P 1976 Oxygen isotope studies of potassic volcanic socks of the Roman Province, central Italy. Cantrib Moleral Petrol 55, 1-31

TURNER, F J & VERHOOGEN, J 1960 Igneous and Metamorphic Petrology, pp. 235-56

Tur l ra , 0 F & GIIIINS, J . 1966 Carbonatites Wiley. Interscience, New Yolk

TWENHOFEL, W. H & BREMER W H 1928 An extension of the Rose Dome intiusives Kansas Bull A m Asrvc Petrol Geol 12, 757-62

ULBRIGH, H H G 1 & COMES, C B 1981 Alkaline rocks from Continental Brazil Earth Sci Reu 17. 135-54.

IJNESCD 1976 Geolog~cal World Arlar , CHOUBERI, G & FAURE- MUREI, A (compilers), UNESCO, Paris

UFION, B G J & THOMAS, J E 1973 Precambrian potassic ultramafic rocks: South Greenland J Petrol 14, 509-34

USSING, N V. 1912 Geology of the country around Julianehib, Greenland Medd~ Grsnland Georri 38, 1-146

VAN KOOIEN, G K 1980 Mineralogy, petrology and geochemistry of an ultrapotassic basaltic suite, Central Sierra Nevada, California, U S A I Petrol 21, 651-84

- 1981 Pb and Sr systematics of ultrapotassic and basaltic rocks from the Central Sierra Nevada, California. Contrib M~neral Perrol 76, 378-85

- & PECK, D L 1977. Highly potassic phonolite of Pliocene age near Metced Peak, central Sierra Nevada, California Geol Soc .dm Abslr Progm 9, 1208-9

VEEVERS, J J 1981 Australian rifted margins In: ScxurION,R. A (ed )Dynamkioj%siiue~Murgmr Geodynam Ser Vol 6, Amer Geophys Union Washington D C pp 72-89

VELDE, D 1967 Sur un iamprophyre hyperalcalin potassique: la minette de Sisco (ile de Corse) Bull Soc Fr ilIin6tal Oistallogr 90, 214-23

- 1968. A new occurrence of priderite ~Mrneral M a g 36 86'7-70

- 1969a Micas from lamprophyres; kersant~tes, minettes and lamproites Bull So< Fr Mineral Cristallogr, 92, 203-23 - 1969b Minettes et kersantites. Une contiibution

A I'ktude des lamprophyres These de Doctorat dEtnt , Faculti des Sciences Univ Paris V1 (unpublished)

-- 1971. A note on an analcite-bearing lamproite from Devonshire Geol Mag 108,201-4

- 1975 Armaicolite-Tikphlogopite-diopside-anal. cite-bearing lamproites from Smoky Butte, Gar- field County Montana Am Mineral 60 566-73

L.arnproztes and K

VENIURELLI, G , BAIESIRA, G , TOSCANI, L & CA- PEDRI, S 1985 The ultrapotassic rocks and the11 geologrcal settlng Geol Arroc Can Progm Absrr 10, A65

- , CAPEDRI, S , Di BAIIISIINI, G , CRAWFORD, A , KOGPRKO, I N & CELESIINI, S 1984a The ultrapotassic rocks from SE Spain Ltihor, 17, 37- 54 - ..

-- , THORPE, R. S , DAL PIAZ, G V , DEL MORO, A & P o n s , P J 1984b Petrogenesis of calc-alkaline, shoshonitic and associated ultrapotassic Oligocene volcanic rocks from the north western Alps, Italy C'ontrib Mme~ol Petrol 86, 209-20

VERWOERD, W J 1966 Fenitization of basic igneous rocks In: TUIIIE, C F. & GISIINS, J (eds) Carbonatiter, pp 295-307 Wiley-Interscience, New York

VILA, J M , HERNkNDEZ, J & VELDE, D 1974 SUI la prhscence d un filon de roche lamproitique (trach- ytepotassiquei olivine) recoupant le flyschdetype (Guerrouch entre Azzaba (ex-Jemmapes) et Ham- mam-Meskoutine dans 1'Est du Constantinois (Algerie)) C R Acad Sci Paris Sir D, 278, 2589-9 1

VOLIMER, R 1976 Rb-Sr and U-Th-Pb systematics of alkaline rocks; the alkaline locks from Italy Geochrm cosmochrm Acta, 40, 281-95

- 1977 Isotopic evidence for genetic relation between acid and alkaline rocks in Italy Contrib Mineral Petrol 60, 109-18 - & HAWKESWORIH, C J 1980. Lead isotopic

composition of the potassic rocks t'rom Roccamon- fina (South Italy) Earth planet Scr Lett 47, 9 1- 101

- & NORR.Y, M H 1983a ilnusual isotopic variations in Nyiragongo nephelinites Nature Lond 301,141-3

-- & -- 1983b Possible origin of K.rich volcanic rocks from Virunga, East Africa, by metasomatism of continental crustal material: Pb, Nd & Sr iso- topic evidence Earth planet Sci Lett 64, 374- 86

-- , OGDEN, P & SCHILIING J G 1981 Nd isotope geochemistry of Leucite Hills ultrapotassic volcan- ism EOS, 62,431

--A , KINGSL.EY, R H & W4GGONER, D G 1984 Nd and Sr isotopes in ultrapotassic volcanic rocks from the Leucite Hills, Wyoming Cbntrib Mineral Prtroi 87, 159-68.

VYAIOV, 0 S & SOBOLEV, V S 1959 (;aussberg, Antarctica hi Geol. Reu 1, 30-40

WADE, A 1917 The geological succession in the west Kimberley district of western Australia Rep Aurt .A.rsoc Adu Sci 73, 93

- & PRIDER, R . T 1940 The leucite-bearing rocks of the West Kimberley area, Western Australia Q I geol Soc Lond 96,39-98

WAGNER, C & VEIDE D 1986a 'The minelalogy of K- richterite-bearing lamproites Am Mineral, 71, 17-77 - & - 1986b Lamproites in N Vietnam? A re-

examination of cocites / Geol 94, 770-6 WAGNER, P A 1914 The diamond fields of' Southern

Africa TranruaalLeader, Johannesburg

-.rzch igneous rocks 189

WAGNER, H C 1954 Geology of the Fredonia Quadrangle Kansas. U S Geol Surv Map GQ49

WAIDMAN, M A, , MCCANDIESS, T E & DUMMEI.I, H '1 1985 Geology and mineralogy of the Twin Knobs # l lamproite, Pike County, Arkansas Geo! Sue. Am Abrtr Progm. 17, 196

WALKER, K R , & MOND, A 1971 Mica lamprophyre (alnoite) from Radok Lake, Prince Charles Moun- tains,Antarctica.Ausr Bur Mine? Resources Geol Geophyr Rec. 1971/108 (unpublished report)

WASHINGION, 11 S 19 17 Chemicalanalysis of igneous rocks, published from 1884-1913 inclusive Prof Pap U S Geo! Surv 99

WAIERS, A. C 1955 Volcanic rocks and the tectonic cycle Geo! SOL Am Spec Pap 62, 703-22

WA~KINSON, D H & CHAO, G Y 19'71 Shortite in kimberlite from the Upper Canada gold mine, Ontario J Geol 81, 229-3:;

WEDEPOHL, K H & MURAMATSKI, Y 1979 The chemical composition of kimberlites compared with the average composition of' three basaltic magma types In: BOYD, F R & MEYER, H 0 A (eds) Diatremes and Diamonds Their Geology Petrology and Geochemirtry Proc 2nd Int. Kimber-. !ire Conf, Vol. I, pp 300-12. American Geophys- ical Union, Washington, DC

WEED, W H & PIRSSON, L. V 1895 Highwood Mountains of ~Montana Geol Soc Am Bull 6, 189-422

- &-- 1896 Missourite, a new leucite rock from the Highwood Mountains, Montana ilm J SLI 2, 315-23

WELIMAN, P 1973 Early Miocene potassium-argon age for the Fitzroy lamproites of Western Aus- tralia I Geol So(. 4ust 19,471-4 , CIJNDARI, A & MCDOIJGALL J 1970 Potassium- argon ages f o ~ lencite..bearing rocks from New South Wales, Australia P?oc R Soc IVS W 103, 103-7

WENDLANDI, R F . 1977a The systemKAISi0,-Si0,- Si0,-CO?: phase relations involving forste~ite, enstatite, sanidine, kalsilite, leucite, vapor, and liquid to 30 k b a ~ Chrnegre Insrn Whrh Yb 76, 435-41 - 19'77b The system K,O-Mg0-A1,0,-Si0,-

H,O-CO,: stability of phlogopite as a function of vapor composition at high pressures and tempera- tures Carneqie Inrtn Wash Yb 76, 441

- & EGGLER, D H 1980a The origins of potassic magmas: I Melting relations in the systems KAISi0,-Mg2Si0,-Si02 and KAlSi0,-Mg0- SO?-CO, to 30 kb Am J Sci 280,185-420

-- & - 1YSOb The origin of potassic magmas I1 Stability of phlogopite in natural spinel iheizolite and in the system KAISiO.,-MgO-SiO,H,O-CO1 at highPand T Am J Sci 280,421-45

-- &- 1 9 8 0 ~ Stability 01 sanidine+torsterite and its bearing on the genesis of' potassic magmas and the distibution of potassium in the upper mantle Earthplaner Sci Lert 51,215-20

WICKHAM, J , ROEDER, D & BRIGGS. G 1976 Plate tectonicsmodelsfor theOuachitaf'oldbelt Geology, 4, 173-6

190 S C Bergman

WILLIAMS, H 1936 Pliocene volcanoes of the Navajo- Hopi country Geol. So< Am Bull 47, 111-72 ,TURNER, F J & GIIBERI, C M 1954 Petrogra- phy: an introduction to the study of rocks in thin sections Freeman, San Francisco

WILL:AMS J F 1891 The igneous rocks oi Arkansas Geol Surv Arkonros, Report I1

WIISON, A N 1982 Diamonds )om Birth to Ererniry, Gemolog Institute of America, Santa Monica, C A

W~MMENAUER. W 1973 Lampsophyse, semilampro- phyre and anchibasaltic dike rocks Forrrchr Mineral 51, 3-67

-- 1974 'The alkaline province of central Europe and Fiance In: SORENSEN, H . (ed )'The AIkalineRockr, pp 238-71 Wiley, New York

WIIKIND, I J 1,369 C1inopl:yroxenes from acid, intermediate and basic rocks, Little Belt Moun tains, Montana Am Mlnerai 54, 13 8-38

- 1973 Igneou!; rocks and related mineral deposits of the Barker Quadrangle, Little Belt Mountains, Montana Pro,< Pap U S Geol Suro 752, 1-58

WOLFF, J E 1938 Igneous rocks of the Crazy Mountains, Montana Geol Soc Am Bull 49, 1569-628.

WONES, D P 1979 The isactionai resorption of complex minerals and the foimation oi strongly femic alkaline rocks In: YODER, H. S. (ed) The Evolurion qf the Igneous Rockr 50th Annluerrory Perrpecriuer, pp 413-22 Princeton University Press, Piinceton, N J

WOODS, M J 1975 Textural and geochemical features

of the Highwood Mountains volcanics, central Montana PhD Therir, University oi' Montana (unpublished)

WYOMING SIATE SURVEY GEOLOGICAL MAP I955 Y ~ G I , K & MAISUMOIO, H 1966 Note on the leucite-

bearing rocks of Leucite Hills, Wyoming, U S A J Fa' Sci Hokkaido Uniu ,l3,301-12

- , ISHIKAWA, H . & KOJIMA, M 1975 Petrology of a lamprophyre sheet in'Tanegashima Island, Kagos- shimaPerfecture, Japan J lap Arroc Win Perrol Econ Geol 70,213-24

YARZA, R A 1895 Roca eruptiva de Fortuna (psovin- cia de Murcia) Bol Comm Mapa Geol E,spana, 20, 349-53

ZARIMAN, R E 1977 Geochronology oi some alkalic rock provinces in eastern and central IJnited States Ann. Rev Earthplanet SCI 5, 257-86 - , BROCK, M R , HEYLE, A V &THOMAS, H H 1967 K-At and Rb-Sr ages of' some alkalic intrusive rocks from central and eastern US Am I SCI 265, 848-70.

ZHUR*IVIEYA, L N , YDRKINA, K. V & RYABEVA Y G 19'78 Priderite, first find in the USSR Dokl flkod Nauk S 5 8' R , Earth Scl. 239, 141-3

ZlNGG, A , HUNZIKER, C , FREY, M & AHRENDI, H 19'76 Age and degree of metamorphism of the Canavese Zone and the sedimentary cover of the Sesia Zone Ehweii &finera/ Pelrogr M ~ t r 56, 761-75

ZIRKEL, F 1870 Unrerruchungen iibe~ die M~krosko- pirche Zurnmmenretzung und Srrukrur der Baralige r trme, Bonn

SIEVEN C BERGMAN, A R C 0 Resou~ces Technology, Exploration and Production Research Center, 2300 W Plano Pkwy, Plauo, Tx 75075 U S A