Igneous rock magma melt - Geology M > 90 % Ultramafic rocks QAPF classification (Streckeisen 1976) Le Maitre ed. (2002) Field classification (Streckeisen 1976) Le Maitre ed. (2002)

1

Vojtěch Janoušek:

Diversity and processes modifying composition of the igneous rocks

Igneous rock ≠ magma ≠ melt

Magma

= melt + crystals + dissolved volatiles (gases)

Why does the chemistry of an igneous rock usually not correspond to that of the parental magma?

• Degassing/volatiles release

• Hydrothermal alteration and low-grade metamorphism

• Crystal accumulation

• Presence of xenocrysts and xenoliths

• Assimilation of such foreign material

• Magma mixing

Photo J. Žák

Geochemical data

Major elements• Expressed in wt. %• Concentration > arbitrary value (0.1 or 1 wt. % depending on the authors)• Usually quoted in the order Si, Ti Al, Fe, Mn, Mg, Ca, Na, K and P• Form the main rock-forming minerals• Controlled by mineral stability limits (P–T conditions), simple mass balance

Trace elements• Concentration < 0.1 %, usually expressed in parts per million, ppm • Substitute in major phases and/or occur as accessory minerals where

they often form essential structural components (zircon ZrSiO4)

Volatiles• H2O+, H2O–, F, Cl, CO2 vs. Loss on ignition, LOI

• Sometimes are distinguished also minor elements (Ti, Mn, P…)• Some elements could be major in some systems, traces in other (K in mantle)

Qualitative parameters

• Average grainsize of the groundmass: coarse-, medium-, fine-grained, glassy

• Observation of minerals present (occurrence of Qtz implies silica saturation)

Classification of igneous rocks

Gill (2010)

2

Quantitative parameters

• Percentages of minerals present (modal composition):colour index: ultramafic, mafic, felsic

melanocratic, mesocratic, leucocratic (but relative terms)


Gill (2010)

Quantitative parameters

• Chemical composition:silica contents: ultrabasic, basic, intermediate, acidTotal Alkali (Na2O + K2O) – Silica diagram (TAS) normative composition


Gill (2010)

Modal vs. normative compositions

Modal composition

= ‚real‘ proportions of minerals in vol. %

• Point counting of standard thin sections or polished (stained) slabs

• Image analysis

• Powder X-ray diffraction

Modal vs. normative compositions

Modal composition= real proportions of minerals in vol. %

Normative composition

CIPW norm (Cross, Iddings, Pirsson and Washington 1902)

• proportions of ideal mineral end-members in wt. %

• need to be divided by density and recast to 100% to get percentages in vol. % to (some extent) comparable with mode

• calculation involves a hierarchical list of rules that tend to be often ambiguous

• does not include hydrous minerals, yields phases often not matching modal mineralogy in the studied igneous rocks, especially acidic ones

‚Improved Granite Mesonorm’ (Mielke and Winkler 1979)

Numerical techniques (least-squares or linear programming)

• Using real (averaged) mineral analyses and recombining them to match – as much as possible – the whole-rock composition

3

Ternary plots

70 % X, 20 % Y, 10 % Z

Q = quartzA = alkali feldsparP = plagioclase (An >5)F = foids(nepheline, leucite,kalsilite, sodalite, nosean, haüyne, cancrinite, analcime…)

M = mafic minerals(micas, amphibole, olivine, pyroxene, accessories…)

Q + A + P + F = 100

M < 90 %

Le Maitre ed. (2002)

Modal (QAPF) classification of plutonic rocks (Streckeisen 1976)

Remarks3 granite = syeno- (a) + monzo- (b)

5 tonalite (M > 10)trondhjemite, plagiogranite (M < 10)

9 monzodiorite (An < 50)monzogabbro (An > 50)

10 anorthosite (M < 10)diorite (An < 50)gabbro (An > 50): separate schemegabbro, troctolite, norite, …

9* quartz monzodiorite (An < 50)quartz monzogabbro (An > 50)

10* quartz anorthosite (M < 10)quartz diorite (An < 50)quartz gabbro (An > 50)

M < 90 % QAPF classification (Streckeisen 1976)


Gabbroic rocks

QAPF classification (Streckeisen 1976)


4

M > 90 %

Ultramafic rocks

QAPF classification (Streckeisen 1976)


Field classification (Streckeisen 1976)


Devising full petrographic name

Root name

Qualifier(s)

• Type mineral(s) present:muscovite–biotite granite (muscovite < biotite)do not list those that correspond to the rock type definition (e.g., diopside in basalt)

• Textural:vesicular, porphyritic, spherulitic, ophitic…

• Nature of phenocrysts:plagioclase-phyric andesiteolivine-augite-phyric basalt

• Chemical features:low-K basalt, peraluminous granite

y = Na2O + K2Ox = SiO2

Analyses have to be recast to 100% anhydrous(volatile-free) basis !!!

ol = CIPW normative olivine q = CIPW normative value:

TAS classification of volcanic rocks (Le Bas et al. 1986)


100 / ( )Q Q or ab an

5



MacDonald (1974)


Irvine and Baragar (1971)

Saturation line

Ol- and foid-normative= undersaturated

Qtz-normative= saturated

Subdivision to alkaline/alkali and subalkaline/subalkaliseries

http://academic.sun.ac.za/earthSci/honours/modules/igneous_petrology.htm

Subdivision of the subalkaline series

Irvine and Baragar (1971)

Definition of tholeiitic and calc-alkaline series

A = Na2O + K2OF = FeOtM = MgO

All in wt. %

Subdivision of the calc-alkaline magmas

Peccerillo and Taylor (1976)

y = K2Ox = SiO2

Both in wt. %

6

Subdivision of the calc-alkaline magmas


Alternatives for weathered samples

Winchester & Floyd (1977) modified by Pearce (1996)

Alternative to TAS

Alternatives for weathered samples

Hastie et al. (2007)

Alternative to the SiO2–K2O plot

B basalt

BA/A basaltic andesite and andesite

D/R* dacite and rhyolite*

* latites and trachytes also fall in the D/R field

Al vs. (Ca) + Na + K balance

Shand (1943)

A/CNK > 1: Peraluminous rocks• have excess Al over the amount

needed to form feldspars• contain biotite, muscovite,

alumosilicates (kyanite, sillimanite or andalusite), cordierite, garnet, tourmaline, topaz or corundum

A/CNK < 1 and A/NK < 1:Metaluminous rocks• presence of Ca- and/or alkali-rich

phases such as amphiboles and pyroxenes indicates an Al deficit

A/CNK ~ 1: Subaluminous rocks

A/NK < 1: Peralkaline rocks • contain aegerine, riebeckite,

arfvedsonite or aenigmatite

2 3

2 2

/ [ .%]Al OA CNK molCaO Na O K O

2 3

2 2

/ [ .%]Al OA NK molNa O K O

Feldspars

KAlSi3O8 – 1/2K2O : 1/2Al2O3

NaAlSi3O8 – 1/2Na2O : 1/2Al2O3

CaAl2Si2O8 – 1CaO : 1Al2O3

7

Al vs. (Ca) + Na + K balance Simple recalculations

2 30.89981 [ .%]FeOt FeO Fe O wt

# 100 [ .%]MgOmg molFeO MgO

# 100 [ .%]MgOMg molFeOt MgO

Niggli (1948) defined simple cationic values. Several of them, si, al, fm, c, alk, k, mg, ti, p, c/fm, and qz are still in use.

Mg# or mg# represent useful index of fractionation for binary plots showing differentiation trends.

Multicationic classifications

De la Roche et al. (1980)Batchelor and Bowden (1985)

1000Cmilli nMW

Millications

MWα molecular weight

nα

number of atoms in the oxide formula (e.g., 2 for Na2O, and again 2 for Al2O3)


De la Roche et al. (1980)Batchelor and Bowden (1985)

Wt. % MW nCationic

proportions

Millications

(per 100 g

of rock)

SiO2 73.60 60.09 x1 1.225 1225

TiO2 0.10 79.90 x1 0.001 1

Al2O3 13.17 101.96 x2 0.258 258

Fe2O3 0.99 159.69 x2 0.012 12

FeO 1.61 71.85 x1 0.022 22

MgO 0.06 40.30 x1 0.001 1

CaO 0.70 56.08 x1 0.012 12

Na2O 3.69 61.98 x2 0.119 119

K2O 5.38 94.20 x2 0.114 114

R1 = 4Si - 11 (Na + K) – 2 (Fe + Ti) = 4900 - 11(233) – 2(12 + 22 + 1) = 2267R2 = 6 Ca + 2 Mg + Al = 72 + 2 + 258 = 332

Example of calculation

8


De al Roche et al. (1980)


P = K–(Na + Ca) proportion of K-feldspar among feldspars

Q = Si/3–(K+Na+2Ca/3) quartz contents

Label Plutonic rocks

go gabbro, diorite, anorthosite

mzgo monzogabbro, monzodiorite

mz monzonites syenite

dq qtz diorite, qtz gabbro, qtz anorthosite

mzdq qtz monzodiorite, qtz monzogabbro

mzq quartz monzonite

sq quartz syenite

to tonalite, trondhjemite

gd granodiorite, granogabbro

ad adamellitegr granite

Debon and Le Fort (1984)


I

Peraluminous domain

muscovite > biotite

II biotite > muscovite

III biotite (± minor amphibole)

IV

Metaluminous domain

biotite, amphibole, ±pyroxene

V clinopyroxene, ±amphibole, ± biotite

VIunusual mineral associations (carbonatites...)

A = Al – (K + Na + 2Ca) peraluminosity

B = Fe + Mg + Timaficity




Wt. % MW n

Millications

(per 100 g

of rock)

SiO2 66.95 60 x1 1116

TiO2 0.35 80 x1 4

Al2O3 16.16 102 x2 317

Fe2O3t 2.95 160 x2 37

MnO 0.10 71 x1 1

MgO 0.68 40 x1 17

CaO 3.96 56 x1 71

Na2O 4.27 62 x2 138

K2O 2.97 94 x2 63

Q = Si/3 – (K + Na + 2Ca/3) = 124P = K – (Na + Ca) = –146A = Al – (K + Na + 2 Ca) = –26B = Fe + Mg + Ti =58

Example of calculation

9

• Partial melting• Segregation• Ascent• Emplacement/

extrusion

• Modal and chemical composition of the source

• Partial melting (+ restite unmixing)

• Differentiation(e.g., fractional crystallization, crystal accumulation)

• Assimilation (or AFC)• Hybridization• Interaction with fluids,

alteration and weathering

Processes determining/modifying the composition of magmatic rocks

Main factors determining the melt chemistry• composition of the source,

• depth ( pressure),

• presence/lack of fluid phase and its composition (H2O, CO2, F, Cl etc.)[fluid-present vs. dehydration melting of Amp, Bt, Mu],

• composition of the restite and/or peritectic phases (Amp/Crd/Grt),

• mechanism of partial melting (equilibrium/batch vs. fractional; in the latter process small amounts are continuously drained from the source),

• degree of partial melting,

• temperature,

• oxygen fugacity.....

Partial melting

Melting can be triggered by:

• Rise of temperature

• Decompression

• Volatile influx

• Dehydration of a water-bearing phase

Migmatite terrains

https://www.geol.umd.edu/facilities/LCP/lcp.htm

Partial melting

Kriegsman (2001)

Partial melting

• leucosomes seldom represent pure melt compositions “back-reactions” with melanosome, or cumulates after melt removal…

• complete removal of solid phases from melt is difficult to achieve:– ‚restite unmixing‘ –

Chappell et al. (1987)

– peritectic phase entrainment –Clemens and Stevens (2012)

https://www.geol.umd.edu/~jmerck/nature/specimens

10

• Thermogravitational diffusiondriven by thermal contrast as well as buoyance (Hildreth 1979)

• Thermal (Soret) diffusion driven by thermal gradient lighter elements concentrate at the hotter interface (Walker a DeLong 1982)• Liquid immiscibility, liquatione.g. immiscible sulphidic and silicate melts

Differentiation

http://www.whitman.edu/geology/winter/JDW_PetClass.htm

Equilibrium (“batch”) crystallizationseparation of newly formed crystals from magma (in a single event)

Fractional crystallizationcontinuous separation of newly formed crystals from the residual magma• Gravity settling

density contrast between the crystals and the melt

• Convectionthermally-induced movement of magma in the magma chamber

• Filter pressing, compactionmelt is expelled from the residual crystal mush mechanically

• Flowage differentiationdriven by the melt movement (typically in a narrow conduit or dykes)

Differentiation

http://www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/

Skaergaard

• Formation of cumulatesMutually touching phenocrysts with interstitial crystallized residual melt

Differentiation

http://www.whitman.edu/geology/winter/JDW_PetClass.htm

• Assimilationo AFC = Assimilation, Fractional Crystallization, o MASH = Melting Assimilation Storage Homogenization),o Zone refining.

• Hybridizationo Homogeneous mixing o Exchange of crystals (xenocrysts)o Mingling

• Interaction with fluidso Volatile strippingo Alterationo Weathering

Open-system processes

11

Xenoliths

• (Accidental) enclaves coming from country-rock complexes

• Evidence for stoping

Assimilation/magma contamination

Sierra Nevada, photo J. Žák

Hudčiče, Central Bohemian Plutonic Complex (CBPC; Czech Republic)

Combined assimilation and fractional crystallization (AFC)

The AFC model assumes that the extra heat needed for assimilation (which is an endothermic process) is provided by the latent heat of crystallization(DePaolo 1981).

De Paolo (1981)

c

a

MM

r

Important is parameter r (the rate of assimilation to fractional crystallization):

The parameter r is determined by the thermal state of the assimilated country rock (will be lower for cold, upper crustal lithologies)In any case it is unlikely to exceed unity.

Late syn-plutonic dykes – Pitcher (1993)

Interaction of magmas with contrasting composition

12

Fernandez & Barbarin (1991)

Interaction of magmas with contrasting composition Mafic microgranular enclaves (MME)

• Hybrid between mafic and felsic magmas (exchange of xenocrysts and co-mingling)

• Often show chilled margins against the host acid magma

• Elliptical, some have lobate contacts• Common in I-type tonalites,

granodiorites, granites…• Missing in S-type leucogranites Sierra Nevada, Photo J. Žák

Teletín and Vepice,CBPC


Field evidence• presence of MME• chilled margins in a mafic magma at

its contact with a felsic one• round or lobate liquid–liquid contacts• net veining with a relatively mobile

felsic magma invading a nearly solidified mafic one, “silicic pipes”

• late syn-plutonic dykes often disrupted into enclave swarms

• exchange of crystals (xenocrysts) e.g., ocellar quartz, rapakivi Fsp

a b

Enclave accumulations– ‘enclave swarms‘

13

1. The initial quenching and multistage crystallization of the presumed hybrids

• Boxy cellular/dendritic plagioclase crystals• Acicular apatite and blade-like biotite • Quartz and K-feldspar oikocrysts

enclosing numerous tiny plagioclase laths and other early formed phases


Hibbard (1995)

• Rapakivi and antirapakivi feldspars, • Plagioclases with resorption surfaces and

thin calcic zones • Ovoid K-feldspars mantled by biotite and/or

amphibole• Quartz ocelli with amphibole rims

2. Exchange of xenocrysts, their resorption & formation of overgrowths


Hibbard (1995)

• Electrons impacting on a luminescent material cause the emission of photons which may have wavelengths in the visible spectrum

• Usually caused by trace-element impurities (activators) or lattice defects

• Suppressed by the so-called quenchers

Cathodoluminescence

Ca-Pl KfsQtz

Bt

Pl

Janoušek et al. (2000, 2006)

• Non-destructive (and uses normal polished thin sections),

• Helps to distinguish phases that look similar under normal petrographic microscope (Fsp, Qtz),

• Enables quick mapping of distribution of some mineral phase (or even different generations thereof) in the thin section,

• Discloses oscillatory and discontinuous growth zoning, resorption surfaces and overgrowths,

• Shows effects of brittle or ductile deformation, alteration and metasomatism.

Cathodoluminescence

mol. % A n40

60

80

100

Nac.A

B0.5 mm

CL dc

Janoušek et al. (2004)

14

I S M A

SiO2 53–76 % 65–74 % 46–70 % High

K2O/Na2O Low High Low Na2O high

Shand‘s index

A/ CNK < 1.1 A/ CNK > 1.1 A/ CNK < 1.0 A/ CNK > 1.0

(87Sr/86Sr)i < 0.705 > 0.707 < 0.705 variable

δ18O < 9 ‰ > 9 ‰ < 9 ‰ variable

Special geochemical

features

Low CaO, high Fe/Mg, Ta, Nb, Zr, REE, F

Source rocks Basic to intermediate

igneous rocks, usually

subduction-related

Sedimentary rocks

Partial melting of subducted oceanic crust,

fractional crystallization from basaltic

magma

Anorogenic settings, variable models, e.g. remelting of granulitic residue left behind by extraction of (normal)

granitic melt

Chappell & White (1974, 1992...), Whalen et al. (1987), Eby (1990), Pitcher (1993), Chappell (1999)…

OKONaCaOOAl

CNKA22

32/

OKONa

OAlNKA

22

32/

[mol. %][mol. %]

Petrogenetic classification of granitoid rocks

Clarke (1992)

Problems of the I-S-M-A classification:

• A mixture of classification according to the source(I, S), process/source (M), geotectonic position (A)

• Some criteria are equivocal(peraluminous granite may form also by fractional crystallization from I-type magmas, Miller 1985)

• Within each of the groups can originate the whole spectrum of compositions, as a function of P–T–X

• Oversimplification(e.g.. hybridization, rock from mixed sources)


Classification of Ishihara (1977):

• ilmenite series – reduced due to the presence of the organic matter

• magnetite series – oxidized

a) Magnetic susceptibility measurement (by hand-held kappameters)

b) Magnetite presence established by the hand-held magnet

c) Biotite colour: oxidized is chocolate or green-brownreduced is bright red

d) K-feldspar colour: oxidized granitoids: Kfs pinkreduced: Kfs white


BATCHELOR, R. A. & BOWDEN, P., 1985. Petrogenetic interpretation of granitoid rock series using multicationic parameters. Chemical Geology, 48, 43-55.

CASTRO A., DE LA ROSA J.D. & STEPHENS W.E. 1990. Magma mixing in the subvolcanic environment: petrology of the Gerena interaction zone near Seville, Spain.– Contrib. Mineral. Petrol.105: 9–26.

CASTRO, A., MORENO-VENTAS, I. & DE LA ROSA, J.D. 1991. H(Hybrid)- type granitoids: a proposed revision of the granite-type classification and nomenclature. Earth-Science Reviews, 31, 237–253.

CHAPPELL, B. W., 1999. Aluminium saturation in I- and S-type granites and the characterization of fractionated haplogranites. Lithos, 46, 535-551.

CHAPPELL, B.W. & WHITE, A.J.R. 1974. Two contrasting granite types. Pacific Geology 8, 173–174.CHAPPELL, B.W. & WHITE, A.J.R. 1992. I- and S-type granites in the Lachlan Fold Belt. Transactions

of the Royal Society of Edinburgh, Earth Sciences, 83, 1–26.CHAPPELL, B.W., WHITE, A.J.R. & WYBORN, D. 1987. The importance of residual source material

(restite) in granite petrogenesis. Journal of Petrology, 28, 571–604.CLARKE, D.B. 1992. Granitoid Rocks. Chapman & Hall, London.COX K.G., BELL J.D. & PANKHURST R.J. 1979. The Interpretation of Igneous Rocks.

George Allen & Unwin, London. CLEMENS, J. D. & STEVENS, G., 2012. What controls chemical variation in granitic magmas? Lithos,

134-135, 317-329.

References and further reading

15

DEPAOLO, D.J. 1981. Trace element and isotopic effects of combined wallrock assimilation and fractional crystallization. Earth Planet. Sci. Lett., 53, 189–202.

DE LA ROCHE, H. et al. 1980. A classification of volcanic and plutonic rocks using R1R2-diagram and major element analyses – its relationships with current nomenclature. Chemical Geology, 29, 183-210.

DEBON, F. & LE FORT, P., 1983. A chemical-mineralogical classification of common plutonic rocks and associations. Transactions of the Royal Society of Edinburgh, Earth Sciences, 73, 135-149.

DEBON, F. & LE FORT, P., 1988. A cationic classification of common plutonic rocks and their magmatic associations: principles, method, applications. Bulletin de Minéralogie, 111, 493-510.

DIDIER, J. & BARBARIN, B. 1991. Enclaves and Granite Petrology. Elsevier, Amsterdam.EBY G.N. (1990) The A-type granitoids: a review of their occurrence and chemical characteristics and

speculations on their petrogenesis. Lithos, 26, 115–134.FERNANDEZ, A. N. & BARBARIN, B., 1991. Relative rheology of coeval mafic and felsic magmas:

nature of resulting interaction processes. Shape and mineral fabric of mafic microgranular enclaves. In: DIDIER, J. & BARBARIN, B. (eds): Enclaves and Granite Petrology. Elsevier, Amsterdam, 263-276.

GILL, R., 2010. Igneous Rocks and Processes: A Practical Guide. J. Wiley, Chichester.HASTIE, A. R. et al. 2007. Classification of altered volcanic island arc rocks using immobile trace

elements: development of the Th-Co discrimination diagram. Journal of Petrology, 48, 2341-2357.HIBBARD, M. J. 1995. Petrography to Petrogenesis. Prentice Hall, New Jersey.


HILDRETH, W., 1979. The Bishop Tuff: evidence for the origin of compositional zonation in silicic magma chambers. Geological Society of America Special Papers, 180, 43-75.

ISHIHARA, S. 1977. The magnetite-series and ilmenite-series granitic rocks. Mining Geology, 27,293–305.

IRVINE, T. N. & BARAGAR, W. R. A., 1971. A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8, 523-548.

JANOUŠEK, V. et al. 2004. Magma-mixing in the genesis of Hercynian calc-alkaline granitoids: an integrated petrographic and geochemical study of the Sázava intrusion, Central Bohemian Pluton, Czech Republic. Lithos, 78, 67-99.

JANOUŠEK, V. et al. 2006. Low-pressure granulites of the Lišov Massif, Southern Bohemia: Viséan metamorphism of Late Devonian plutonic arc rocks. Journal of Petrology, 47, 705-744.

KRIEGSMAN, L. M., 2001. Partial melting, partial melt extraction and partial back reaction in anatectic migmatites. Lithos, 56, 75-96.

LE BAS, M. J. ET AL. 1986. A chemical classification of volcanic rocks based on the total alkali-silica diagram. Journal of Petrology, 27, 745-750.

LE MAITRE, R. W. (ed.), 2002. Igneous Rocks: A Classification and Glossary of Terms: Recommendations of the International Union of Geological Sciences, Subcommission on the Systematics of Igneous Rocks. Cambridge University Press, Cambridge.

MACDONALD, R., 1974. Nomenclature and petrochemistry of the peralkaline oversaturated extrusive rocks. Bulletin Volcanologique, 38, 498-516.


Použitá a doporučená literatura

MILLER C.F. (1985) Are strongly peraluminous magmas derived from pelitic sources?

The Journal of Geology, 93, 673–689.NIGGLI, P., 1948. Gesteine und Minerallagerstätten. Birkhäuser, Basel.PEARCE, J. A., 1996. A user's guide to basalt discrimination diagrams. In: WYMAN, D. A. (ed.):

Trace Element Geochemistry of Volcanic Rocks: Applications for Massive Sulphide Exploration. Geological Association of Canada, Short Course Notes 12, 79-113.

PECCERILLO, A. & TAYLOR, S. R., 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contributions to Mineralogy and Petrology, 58, 63-81.

PITCHER, W.S. 1993. The Nature and Origin of Granite. Chapman & Hall, London.ROLLINSON H.R. 1993. Using Geochemical Data: Evaluation, Presentation, Interpretation.

Longman, London.SHAND, S. J., 1943. Eruptive Rocks. Their Genesis, Composition, Classification, and Their Relation

to Ore-Deposits with a Chapter on Meteorite. John Wiley & Sons, New York.STRECKEISEN, A., 1976. To each plutonic rock its proper name. Earth-Science Reviews, 12, 1-33.VERNON, R.H. 1984. Microgranitoid enclaves in granites – globules of hybrid magma quenched in a

plutonic environment. Nature, 309, 438–439VERNON, R.H. 1990. Crystallization and hybridism in microgranitoid enclave magmas:

microstructural evidence. Journal of Geophysical Research, 95, 17849–17859.

Použitá a doporučená literatura

WALKER, D. & DELONG, S. E., 1982. Soret separation of mid-ocean ridge basalt magma.Contributions to Mineralogy and Petrology, 79, 231-240.

WINCHESTER, J. & FLOYD, P., 1976. Geochemical magma type discrimination; application to altered and metamorphosed basic igneous rocks. Earth and Planetary Science Letters, 28, 459-469.

WHALEN J.B., CURRIE K.L., CHAPPELL B.W. (1987) A-type granites: geochemicalcharacteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology, 95,407–419.

WILSON M. 1989. Igneous Petrogenesis. Unwin Hyman, London.

16

Web links

• Cornell University - Geochemistry 455 (W.M. White)http://www.geo.cornell.edu/geology/classes/geo455/Geo455.html

• Fifth Hutton Symposiumhttp://www.neckers.siu.edu/ferre/hutton.html

• Igneous and metamorphic geology class materials (J. D. Winter, Whitman University)http://www.whitman.edu/geology/winter/JDW_PetClass.htm

• Advanced petrology (J.-F. Moyen, University of Stellenbosch, South Africa)http://academic.sun.ac.za/earthSci/honours/modules/igneous_petrology.htm

Documents

Igneous rock magma melt - Geology M > 90 % Ultramafic rocks QAPF classification (Streckeisen 1976) Le Maitre ed. (2002) Field classification (Streckeisen 1976) Le Maitre ed. (2002)