Lithos 112S (2009) 806–821

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Lithos

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The diamonds of South Australia

Ralf Tappert a,⁎, John Foden a, Thomas Stachel b, Karlis Muehlenbachs b, Michelle Tappert c, Kevin Wills d

a Geology and Geophysics, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, 5005, South Australia, Australiab Department of Earth and Atmospheric Sciences, 1-26 Earth Science Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E3c Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, 5005, South Australia, Australiad Flinders Mines Ltd., Norwood, 5000, South Australia, Australia

⁎ Corresponding author. Tel.: +61 8 8303 5844; fax:E-mail address: ralf.tappert@adelaide.edu.au (R. Tap

0024-4937/$ – see front matter © 2009 Elsevier B.V. Adoi:10.1016/j.lithos.2009.04.029

a b s t r a c t

a r t i c l e i n f o

Article history:Received 15 September 2008Accepted 20 April 2009Available online 19 May 2009

Keywords:Sublithospheric diamondsFerropericlasePlacer diamondsSouth AustraliaKimberlitesPermian glaciation

Diamonds in South Australia occur in kimberlites at Eurelia (Orroroo), and in placer deposits, which includethe Springfield Basin and the historic Echunga goldfield. To identify the kimberlitic and mantle sources of theplacer diamonds, and to determine any possible connections between the placer diamonds and the diamondsfrom the Eurelia kimberlites, we examined the physical and compositional characteristics, and the mineralinclusion content of 122 diamonds from the Springfield Basin and 43 diamonds from kimberlites at Eurelia.Additional morphological data for three Echunga diamonds are also given. Most of the diamonds from theSpringfield Basin are similar to the diamonds from Eurelia with respect to their crystal shapes, surfacetextures, and colors. The diamond populations from both areas are characterized by a high abundance of low-nitrogen (b100 ppm) diamonds with variable nitrogen aggregation states. The stable carbon isotopecompositions of the Springfield Basin diamonds are similar to the Eurelia diamonds with δ13C values in therange −20.0 to −2.5‰, and a mode at −6.5‰. Ferropericlase inclusions in two diamonds from theSpringfield Basin are consistent with ferropericlase-bearing mineral inclusion assemblages found in theEurelia diamonds and indicate that part of the diamond population from both areas is of sublithosphericorigin. One diamond from the Springfield Basin contained an inclusion of lherzolitic garnet. The overallsimilarities between the Springfield Basin and Eurelia diamonds indicates that the bulk of the SpringfieldBasin diamonds are derived from kimberlitic sources that are similar (or identical) to those at Eurelia.However, three diamonds from the Springfield Basin are markedly distinct. These have well-developedcrystal shapes, large sizes, yellow body colorations, and brown irradiation spots. The brown irradiation spotsand abrasion textures provide evidence that these diamonds are much older than the other diamonds in theSpringfield Basin, and that they are derived from distal kimberlitic sources. The diamonds are most likelyderived from Permian glacigene sediments and may ultimately be sourced from kimberlites on the EastAntarctic craton. Abrasion textures and brown irradiation spots are also present on diamonds from Echunga.This provides a link to the three “old” Springfield Basin diamonds and other alluvial diamonds in EasternAustralia, and suggests that Permian glaciations caused a widespread distribution of diamonds over largeparts of southern Australia, which at that time was part of the supercontinent Gondwana.

© 2009 Elsevier B.V. All rights reserved.

1. Introduction

In South Australia, diamonds occur in kimberlites, placer deposits,and as isolated grains fromunknown sources in surface samples (Fig.1).Most of the known kimberlites in South Australia are located in theAdelaide Fold Belt (Colchester, 1972; Ferguson and Sheraton, 1979;Stracke et al., 1979; Scott Smith et al., 1984), where they occur as a semi-continuous, northwest trending dyke–swarm (Fig. 1). Two additionalkimberlite clusters are present on the adjacent Gawler Craton; these arelocated near Cleve and Elliston/Mount Hope (Atkinson et al., 1990;

+61 8 8303 4347.pert).

ll rights reserved.

Wyatt et al.,1994; Fig. 1). Althoughmore than 150 individual kimberliteoccurrences have been discovered within South Australia, the onlymarginally diamondiferous kimberlites, so far, are restricted to theEurelia area in the Adelaide Fold Belt, ∼20 km north of Orroroo (ScottSmith et al.,1984). A notable feature of the diamonds from Eurelia is thepresence of ferropericlase-bearing mineral inclusion assemblages,which suggests that part of the diamond population from Eurelia is ofunusually deep, sublithospheric origin (Scott Smith et al., 1984; Tappertet al., 2009).

Diamond placer deposits within South Australia are located in theEchungaarea, (∼30kmSEAdelaide), and in theSpringfieldBasin (∼50kmNWOrroroo) (Fig.1). Diamonds at Echungawere first discovered in 1859,as a rare byproduct during placer gold mining. Until around 1900, up to50 diamonds were found at Echunga, with the largest stone weighing

Fig. 1. Locations of diamond and kimberlite occurrences in South Australia.

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∼5.3 carats (Gommers,1988).Onlyfiveof thediamonds fromtheEchungagoldfield are still known to exist. At Echunga, the diamonds wererecovered from auriferous Tertiary conglomerates, which are devoid ofindicator minerals commonly associated with diamonds. The primarysources of the Echunga diamonds are unknown.

The Springfield Basin is a small sedimentary basin (∼9 km2),which unconformably overlies folded sedimentary rocks of theAdelaidean supergroup. Within the Springfield Basin, diamondsoccur exclusively in the basal conglomerate, which is considered tobe Permian in age (Drexel and Preiss, 1995). The conglomerate isoverlain by argillites and partially coal-bearing sediments of approxi-mately Late Triassic age (Amtsberg, 1969). Within the basal conglom-erate of the Springfield Basin, the diamonds occur together with

indicator minerals, including magnesiochromite, picroilmenite,pyrope, and chrome diopside. During bulk sampling in the SpringfieldBasin, around 200 diamonds were recovered from N2000 tons ofconglomerate, with the largest diamond weighting 0.34 carat. Al-though the diamondiferous kimberlites at Eurelia are located less than40 km southeast of the Springfield Basin, they have not been con-sidered to be the source of the Springfield Basin diamonds, because oftheir apparently younger (Jurassic) ages.

In order to gain information about possible kimberlitic sources and themantle origins of the placer diamonds in South Australia, we analyzed thephysical and compositional characteristics aswell as themineral inclusioncontent of placer diamonds from the Springfield Basin and the Echungaarea. In order to determine possible links between the placer diamonds

Table 1Physical, compositional, and isotopic characteristics of diamonds from the Springfield Basin and kimberlites in the Eurelia area, South Australia.

Surface textures

Sample Weight[mg]

Shape Shape comment Color Ir.Spots.

Defor. Sh.Lam.

Trigons Hillocks Terraces Frosting Corr.Sc.

Etch Ruts Other UV-color N-Conc.[atomic ppm]

N-Agg.[%B]

Type Hydrogen δ13C[‰ PDB]

Springfield BasinFLIN2-01 20.2 I DO fragment, broken (new) YL X X X BL 820 27 IaAB −7.13FLIN2-02 14.8 D Broken (old) YL BR, GR X X Inclusion cavity GR 472 1.8 IaA −6.39FLIN2-03 3.7 O Broken (old) CL X X X X BL 25.2 95 IaB −6.64FLIN2-04 4.6 I DO fragment, bloken

(new+old)YL X X X X BL 1820 78 IaAB −5.59

FLIN2-05 3.9 PsA BR X X X X YL–GR 197 2.3 IaA −6.13FLIN2-06 3.6 Ps Distorted BR X X YL–GR

(BL)15.2 46 IaAB −6.63

FLIN2-07 3.4 OA Multiply twinned, one sideconcave

CL X X X Triangular plates BL 955 67 IaAB −3.71

FLIN2-08 10.2 D Fragment, broken (new) BR X X X BL 297 35 IaAB n.a.FLIN2-09 6.3 I Fragment, broken (new) BR X X X YL–GR

(BL)73.1 12 IaAB n.a.

FLIN2-10 6.5 D Fragment, broken (old) PBR X X BL 1079 (785) 63 (59) IaAB n.a.FLIN2-11 3.9 I D fragment, broken (old+new) YL X X BL 1050 63 IaAB n.a.FLIN2-12 6.1 I D fragment, broken (old) BR X X YL–GR 161 42 IaAB n.a.FLIN2-13 3.2 O CL X X X BL 20.2 99 IaB n.a.FLIN2-15 4.8 I O fragment, broken (new) CL X BL 27.9 0.0 IaA −5.37FLIN2-16 9.0 I Fragment, broken (old+new) BR GR X X BL 0.0 II n.a.FLIN2-17 4.3 I Fragment, broken (old+new) CL X X BL 1199 (1071) 63 (61) IaAB −6.79FLIN2-18 14.7 D Flattened YL BR, GR X X GR 594 0.0 IaA −4.71FLIN2-19 7.8 I Fragment, broken (old+new) PBR X X BL 727 (748) 50 (50) IaAB n.a.FLIN3-01 1.4 I O fragment, broken (new) YL X X X BL 9.9 63 IaAB −6.10FLIN3-02 2.2 I Fragment, broken (new) BR X YL–GR 209 3.4 IaA n.a.FLIN3-03 3.2 O CL X X BL 909 16 IaAB −6.91FLIN3-04 11.1 Ps Distorted, broken (old) PBR X X X X X YL–BL 24.1 16 IaAB n.a.FLIN3-05 7.8 I Fragment, broken (old) CL X X BL 680 26 IaAB −5.51FLIN3-06 1.9 I Fragment, broken (new) PBR X X BL 0.0 II n.a.FLIN3-07 4.3 D Broken (old) CL GR X X X X X BL 409 52 IaAB −7.13FLIN3-08 6.7 I Fragment, broken (old), twinned PBR GR X X X X X YL–BL 14.8 16 IaAB −11.47FLIN3-09 7.3 IA Fragment, broken (old) CL GR X X X Enhanced lustre BL 1012 (1133) 63 (59) IaAB −5.25FLIN3-10 9.0 I Fragment CL X X X BL 1243 67 IaAB n.a.FLIN3-11 5.0 O BR X X X YL–GR 93.2 26 IaAB n.a.FLIN3-12 3.3 OA Broken (new) CL X X X BL 30.0 39 IaAB n.a.FLIN3-13 4.2 I D fragment, broken (old) BR X X X X X BL 514 39 IaAB n.a.FLIN3-14 3.9 Ps PBR GR X X X X X BL 17.4 56 IaAB n.a.FLIN3-15 3.8 Ps Flattened PBR X X X X Inclusion cavity BL 7.0 64 IaAB −6.40FLIN3-16 5.0 OA Partially twinned, stepped,

broken (old)PBR X X X X X YL–BL 72.1 19 IaAB n.a.

FLIN3-17 2.4 O Fragment, broken (old) PBR X X X YL–BL 69.3 (53.2) 16 (21) IaAB n.a.FLIN3-18 2.5 O Broken (old), slightly stepped PBR X X X BL 17.8 71 IaAB n.a.FLIN3-19 6.6 I D fragment, broken (old) CL GR X X X X Enhanced lustre BL 0.0 II −20.01FLIN3-20 5.0 I Fragment, broken (old) CL X X X X X BL 1126 90 IaB Very high −10.97FLIN3-21 3.2 OA Stepped PBR GR X X YL–GR 88.1 0.0 IaA −4.83FLIN3-22 4.0 I Fragment, broken (old) PBR X BL 5.0 100 IaB −6.68FLIN3-23 5.0 I Fragment, broken (old+new) BR X X X YL–GR 102 (344) 22 (7.9) IaAB n.a.FLIN3-24 3.6 I D fragment, broken (old) BR X X YL–GR

(BL)58.9 47 IaAB n.a.

FLIN3-25 3.4 I Fragment, broken (old+new) CL X X X X X X Enhanced lustre BL 14.2 46 IaAB n.a.FLIN3-26 3.6 I Fragment, broken (old+new) PBR X X X X X Circular micro pits BL 0.0 II −8.98FLIN3-27 4.9 I Fragment, broken (new) BR X YL–GR 387 0.6 IaA n.a.

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FLIN3-29 3.3 PsA PBR X X X X YL–GR 406 3.5 IaA n.a.FLIN3-30 4.0 I Fragment, broken (old+new) PBR X X X X BL 62.9 69 IaAB n.a.FLIN4-01 0.8 I Fragment, broken (new) BR X X X X BL 0.0 II −2.80FLIN4-02 1.8 PsA PBR X X X X X X BL 51.8 (101) 52 (49) IaAB n.a.FLIN4-03 1.3 Ps PBR X X X X YL–BL 625 (491) 3.8

(5.9)IaA −5.53

FLIN4-04 0.9 O PBR X X X X BL 7.0 100 IaB −6.59FLIN4-06 7.2 D Flattened, half, broken (old) YL X X X BL 17.8 (32.6) 5.0 (31) IaA n.a.FLIN4-07 3.2 D One remnant O face PBR X X X X BL 71.2 16 IaAB n.a.FLIN4-08 1.3 DA Aggregate of two CL X X X X BL 8.9 100 IaB −4.48FLIN4-09 1.7 O Flattened, distorted, stepped BR X Triangular plates YL–GR 78.9 (268) 0.0 (15) IaA −4.00FLIN4-10 1.3 I D fragment, broken (old) PBR X BL 930 27 IaAB n.a.FLIN4-11 3.2 D Broken (old+new) BR X X X YL–GR 63.2 (79.4) 23 (11) IaAB −6.16FLIN4-12 0.5 PsA BR X X X X X BL 745 72 IaAB n.a.FLIN4-13 0.8 O CL X X BL 1054 100 IaB −7.00FLIN4-14 3.6 D Half, one side concave,

broken (old)CL X X X BL 519 (149) 95 (77) IaB Very high n.a.

FLIN4-15 2.4 PsA Fragment, broken (old+new) BR X X X X BL 20.5 86 IaAB −6.08FLIN4-16 2.0 D Flattened, twinned CL X X BL 0.0 II −6.62FLIN4-17 2.2 Ps Fragment, broken old PBR X X X X BL 42.4 60 IaAB −6.83FLIN4-18 4.7 I D fragment, broken (new+old) CL X BL 107 (96.7) 73 (89) IaAB −8.97FLIN4-19 6.5 I D fragment, broken (new+old),

distortedBR X X YL–GR

(BL)30.7 54 IaAB −7.22

FLIN4-20 4.3 I Fragment, broken (new+old) BR X X X X YL–GR 118 (91.1) 12 (0.0) IaAB −6.40FLIN4-21 4.2 I Fragment, broken (new+old) PBR GR X X X X Circular micro pits BL 808 51 IaAB n.a.FLIN4-22 2.6 D D fragment, broken (old) YL X X Enhanced lustre BL 1185 (1076) 62 (60) IaAB n.a.FLIN4-23 4.4 D D fragment, broken (new) CL X X BL 573 (648) 45 (50) IaAB n.a.FLIN4-24 1.2 OA PBR X X X X BL 8.6 92 IaB n.a.FLIN4-25 2.2 Ps PBR X X X X X X Inclusion cavity BL 29.6 25 IaAB n.a.FLIN4-26 1.1 PsA CL X X X X BL 227 100 IaB −4.03FLIN5-01 2.3 I D fragment, broken (new) YL GR X X X X X n.a. 0.0 II n.a.FLIN5-02 3.1 I Fragment, broken (old) YL GR X X X YL–BL 288 (269) 18 (10) IaAB n.a.FLIN5-03 1.8 Ps Distorted, small pertrusion BR X X X X YL–GR

(BL)76.9 50 IaAB n.a.

FLIN5-04 2.5 D Fragment, broken (old) YL GR X X X BL 758 (751) 40 (37) IaAB n.a.FLIN5-05 1.0 O Macle CL X X Triangular plates BL 19.6 71 IaAB n.a.FLIN5-06 4.0 OA Broken (old+new) CL X X X BL 35.0 100 IaB −4.32FLIN5-07 1.7 O Twinned, broken (new) CL X X X BL 22.9 86 IaAB n.a.FLIN5-08 0.6 D Distorted PBR X BL 9.6 100 IaB −3.26FLIN5-09 0.8 D Distorted PBR X X X BL 1.9 100 IaB −5.79FLIN5-10 0.9 Ps PBR X X X X X BL 9.0 83 IaAB n.a.FLIN5-11 0.9 DA Distorted CL X BL 951 (581) 87 (71) IaAB Very high −9.65FLIN5-12 4.3 OA Aggregate of two, broken (new) BR X X X BL 1.3 46 IaAB −6.53FLIN5-13 4.9 I Fragment, broken (new+old) PBR X X X X X BL 68.0 (25.5) 47 (5.5) IaAB n.a.FLIN5-14 3.6 I Fragment, broken (old) YL X X X X X X BL 572 100 IaB n.a.FLIN5-15 3.4 PsA Aggregate of two PBR X X X X X BL 9.0 66 IaAB n.a.FLIN5-16 1.8 O Rounded macle twin PBR X X X X BL 4.2 90 IaB n.a.FLIN5-17 2.5 Ps Broken (old) PBR X X X BL 9.9 100 IaB n.a.FLIN5-18 1.1 D Perfect PBR X X X BL 404 87 IaAB Very high −9.57FLIN5-19 2.8 D Broken (new) BR X X X YL 25.1 49 IaAB n.a.FLIN5-20 1.0 D CL X X X BL 175 98 IaB High −12.09FLIN5-21 1.1 I Fragment, broken (old) PBR X X X BL 36.8 49 IaAB −6.50FLIN5-22 1.1 D Flattened, broken (old) BR X X X YL–GR 353 0.9 IaA n.a.FLIN5-23 1.4 OA Aggregate of two PBR X X X X BL 78.9 47 IaAB n.a.FLIN5-24 0.4 I PBR X X X X BL 27.7 90 IaAB n.a.FLIN5-25 1.3 O PBR GR X X BL 5.7 98 IaB n.a.FLIN5-26 0.5 O Twinned, stepped (rounded) BR X X YL–BL 79.1 18 IaAB n.a.FLIN5-27 1.0 I Fragment, broken (old+new) PBR GR X X X YL–BL 68.0 2.5 IaA −7.01FLIN5-28 0.7 Ps Partly concave PBR X X BL 548 26 IaAB n.a.FLIN5-29 1.0 Ps Fragment, broken (old) PBR GR X X X BL 75.9 74 IaAB −6.49

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Table 1 (continued)

Surface textures

Sample Weight[mg]

Shape Shape comment Color Ir.Spots.

Defor. Sh.Lam.

Trigons Hillocks Terraces Frosting Corr.Sc.

Etch Ruts Other UV-color N-Conc.[atomic ppm]

N-Agg.[%B]

Type Hydrogen δ13C[‰ PDB]

Springfield BasinFLIN5-30 1.6 Ps One side flat PBR X X X X BL 41.4 33 IaAB n.a.FLIN6-01 1.7 O Twinned CL GR X X X BL 641 1.9 IaA n.a.FLIN6-02 2.1 PsA Aggregate of two PBR X X X BL 26.1 49 IaAB n.a.FLIN6-03 0.7 Ps Aggregate of two PBR X X X BL 26.6 94 IaB n.a.FLIN6-04 3.9 D One side remnant O face,

broken (old)PBR X X X X X BL 98 IaB −6.14

FLIN6-05 1.0 D CL X X X X BL 14.1 77 IaAB n.a.FLIN6-06 0.5 I O fragment, broken (new) PBR X X BL 13.6 93 IaB n.a.FLIN6-07 0.7 D Fragment, broken (old) PBR X X X X PI–BL 117 100 IaB −5.81FLIN6-08 2.2 I Fragment, broken (old) PBR X X X X X X BL 41.0 100 IaB n.a.FLIN6-09 2.0 I D fragment, broken (new) PBR X X X BL 14.2 87 IaAB n.a.PBS-01 68.3 D Macle, broken (new) YL BR X X X X Network patterns,

percussion marksGR 417 0.0 IaA n.a.

SL1-01 0.7 I Fragment, broken (new) CL X BL 625 53 IaAB n.a.SL1-02 0.5 I Fragment, broken (new) CL X X BL 1512 72 IaAB n.a.SL2-01 3.5 D Flattened, broken (old) YL GR X X X BL 657 (646) 35 (48) IaAB n.a.SL2-02 0.9 Ps D side flat, broken (new) PBR X X X YL–BL 95.8 6.5 IaA −5.56SL2-03 1.0 O Macle twin, stepped,

broken (old)PBR X X X X BL 23.3 45 IaAB n.a.

SL2-04 0.6 Ps Stepped (rounded) PBR X X X X GR 173 88 IaAB High n.a.SL3-01 5.8 PsA D side flat BR X X X X X YL–GR 189 13 IaAB −4.83SL3-02 0.5 OA Stepped BR X X X YL–GR 157 28 IaAB −2.75SL3-03 0.5 D Fragment, broken (old) PBR X X BL 594 34 IaAB −4.22SL4-01 0.2 D Fragment, broken (old) PBR X BL 1015 35 IaAB n.a.

Eurelia K3 kimberliteFBS-03-01 6.6 I DO fragment, broken

(old+new)BR X X X X X OR 16.6 71 IaAB −6.39

FBS-03-02 1.7 I DO fragment, broken (old) BR X X X X X YL–GR(BL)

18.3 0.0 IaA −8.30

FBS-03-03 5.0 I DO fragment, broken(old+new)

BR X X X X X OR 14.2 71 IaAB −6.32

FBS-03-04 3.0 D PBR X X X BL 7.1 97 IaB −4.35FBS-03-05 5.0 D PBR X X X X BL 181 56 IaAB −8.60FBS-03-06 4.3 DOA Aggregate of two PBR X X X X X BL 8.6 73 IaAB −1.88FBS-03-07 2.7 Ps PBR X X X X BL 5.5 69 IaAB −6.22FBS-03-08 7.9 OD Broken (old+new) BR X X X Triangular plates PI–BL 238 (50.9) 100

(100)IaB n.a.

Eurelia K2 kimberliteFBS-04/1-01 3.2 D Broken (old) PBR X X X X X Shallow

depressionsBL 232 79 IaAB −9.40

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FBS-04/1-02 6.8 DOA PBR X X X X X BL 9.6 100 IaB −5.23FBS-04/2-01 3.1 D One face remnant O CL X X X X X X BL 660 16 IaAB −3.96

Eurelia K7 kimberliteFBS-05-01 13.8 I PBR X X X X X YL 31.2 40 IaAB −15.74FBS-05-02 6.6 DOA PBR X X X X YL–GR

(BL)32.4 42 IaAB −7.24

FBS-05-03 5.0 DO PBR X X X X X BL 21.9 93 IaB −4.54FBS-05-04 13.0 DA Slightly distorted CL X X X BL 27.2 84 IaAB −6.46FBS-05-05 3.7 OD Stepped PBR X X X X Triangular plates YL–GR 280 1.5 IaA −5.45FBS-05-06 2.8 I CL X X X X YL–GR 54.1 46 IaAB −15.75FBS-05-07 11.6 DA PBR X X X X BL 556 51 IaAB −6.96FBS-05-08 17.6 I CL X X X X X X X Corrosion

sculpturesBL 759 (823) 52 (53) IaAB n.a.

FBS-05-09 2.5 I D fragment, broken (new) BR X X X YL–GR 240 2.8 IaA −5.87FBS-05-10 1.8 O Partly twinned (macle) CL X X BL 21.8 55 IaAB −4.35FBS-05-11 1.8 O Twinned (macle) CL X X BL 24.9 92 IaB −3.75FBS-05-12 1.7 O Twinned (macle) CL X X Inclusion cavity BL 39.0 84 IaAB −2.45FBS-05-13 3.8 DO Elongated fragment,

broken (old)CL X X X X X BL 13.5 100 IaB −6.05

FBS-05-14 1.8 DO Broken (old) PBR X X X X X Inclusion cavity BL 14.8 36 IaAB −4.59FBS-05-15 1.7 Ps PBR X X X Triangular plates YL–GR 116 1.0 IaA −4.87FBS-05-16 0.9 D Broken (old) PBR X X X PI–BL 856 25 IaAB −4.65FBS-05-17 1.0 D Elongated CL X X BL 19.6 82 IaAB −6.09FBS-05-18 1.5 I D fragment, broken (old+new) BR X X X X YL–GR 71.8 29 IaAB −6.14FBS-05-19 0.9 PsA CL X X X X YL–GR 446 0.0 IaA −4.85FBS-05-20 1.0 Ps PBR X X X X Triangular plates YL–GR 218 0.0 IaA −5.95FBS-05-21 0.7 O Broken (old) CL X X BL 51.0 2.7 IaA −6.05FBS-05-22 0.9 D Flattened, distorted PBR X YL–GR 23.6 17 IaAB n.a.FBS-05-23 0.6 DO Fragment, broken (new) PBR X YL–GR 37.8 4.8 IaA −4.16FBS-05-24 1.5 D Broken (old) CL X X X YL–GR 249 5.4 IaA −5.57FBS-05-25 0.5 I Skeletal fragment CL X BL 1311 50 IaAB −5.94FBS-05-26 0.8 OA CL X X BL 24.2 28 IaAB −3.08FBS-05-27 0.4 I DO fragment, broken (new) BR X X X YL–GR 253 8.4 IaA −6.18FBS-05-28 0.8 OA CL X X BL 45.2 11.9 IaAB −6.09FBS-05-29 0.8 OA CL X X BL 52.9 (66.9) 25 (27) IaAB −6.05FBS-05-30 1.6 C Distorted GRY YL 862 13 IaAB −4.30FBS-05-31 0.1 I Fragment, broken (old) CL X X n.a. 2568 (2853) 39 (40) IaAB −6.03FBS-05-32 6.2 Ps One side concave BR X X X X n.a. 10.8 50 IaAB −7.02

Abbreviations: O—Octahedral, D—Dodecahedral, I—Irregular, Ps—Pseudohemimorphic, A—Aggregate, YL—yellow, CL—colorless, BR—brown, PBR—pale brown, GRY—grey, GR—green, BL—blue, PI—pink.Ir.Spot.—Irradiation spots, Defor.—Derformation Lines, Sh.Lam.—Shield Laminae, Corr.Sc.—Corrosion Sculpture, N-Conc.—Nitrogen concentration, N-Agg.—Nitrogen Aggregation, ()—rim composition/color, n.a.—not analyzed.

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Fig. 2. Distribution of crystal shapes of diamonds from the Springfield Basin and Eureliakimberlites.

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and known kimberlite derived diamonds, we also included a comparisonto diamonds from Eurelia kimberlites.

2. Samples and analytical techniques

One hundred and twenty-two diamonds from the Springfield Basinand 43 diamonds from three different kimberlite dykes in the Eureliaarea (K2, K3, and K7) were examined (Table 1). The diamonds wererecovered by Flinders Diamonds Ltd. during sampling programsbetween 1998 and 2007. An additional three diamonds from theEchunga goldfields were provided by the South Australian Museumand the Department of Primary Industries and Resources SouthAustralia (PIRSA) for a morphological study.

All diamonds were visually examined and their physical char-acteristics were documented (Table 1). UV fluorescence character-istics of the diamonds were analyzed using a Leica MZ16FA stereomicroscope attached to a HBO mercury short arc lamp. Concentrationand aggregation state of nitrogen impurities in the Springfield Basinand Eurelia diamonds were determined by Fourier transform infrared(FTIR) spectroscopy using a Thermo Nicolet Nexus 470 FTIR spectro-meter equipped with a Nicolet Continuum infrared microscope at theUniversity of Alberta. Spectra were collected in transmittance mode,between 650 and 4000 cm−1 (2.5–15.4 µm), at a resolution of 4 cm−1,and a spot size of 100×100 µm. After conversion to absorptioncoefficients, the spectra were de-convoluted into the A, B and Dcomponents. Concentrations of nitrogen in A- and B-centers werecalculated using the absorption strength at 1282 cm−1 (Boyd et al.,1994; Boyd et al., 1995). The detection limits depend strongly on thequality of the fragments, but are generally in the range 5–20 ppm. Therelative errors for concentration and aggregation state for eachmeasurement are in the range 10–20%. If a high-quality spectrumcould not be collected through the whole diamond, the diamond wascrushed, and clear, inclusion free fragments selected for analysis.Multiple analyses through different parts of the diamond (core–rim)have been performed whenever possible, in order to detect variationsof the nitrogen content and the aggregation state (Table 1). Thepresence of atomic hydrogen as impurity in the diamonds, whichcauses a sharp absorption band at 3107 cm−1 in the FTIR spectrum(Runciman and Carter, 1971), has been monitored. The carbon isotopecompositions of selected samples from the Springfield Basin andEurelia were determined with a Finnigan MAT 252 gas flow massspectrometer at the University of Alberta, after combusting 0.5–1.5mgof inclusion free diamond fragments together with ∼1 g CuO as anoxygen source in a sealed and evacuated quartz tube at 1000 °C for∼12 h. The results are given relative to the V-PDB standard (Coplenet al., 1983). Instrumental precision and accuracy is on the order of±0.02‰.

Mineral inclusions within the diamonds were released from thehost diamonds by crushing. Completely released inclusions weremounted in brass rings and then polished. Partially exposed inclusionswere analyzed in-situ. The major and minor element compositions ofthe inclusions were determined with a CAMECA SX-51 electronmicroprobe at the University of Adelaide. The measurements weremade using a 15 kV acceleration voltage and 20 nA probe current, witha detection limit for oxide species of ∼100 ppm (except Na2O:200 ppm). Accuracy and precisionwere tested on secondary standardsand are within ∼1.0% relative for the major elements.

3. Results

3.1. Diamond sizes and crystal shapes

The diamonds from the Springfield Basin and the Eureliakimberlites range in size from 0.5 to 5 mm in diameter and weighbetween 0.1 and 68.3 mg (0.0005–0.34 carat), with an averageweightof 3.9 mg (0.02 carat) (Table 1). Diamonds from both areas present a

range of crystal shapes, but the relatively small number of diamondsmay not fully represent the entire diamond population. Diamondswith predominantly octahedral shapes are present in similar propor-tions in the Springfield Basin and Eurelia kimberlites (Fig. 2).Dodecahedral diamonds are less abundant in the Springfield Basin(23%) than in the Eurelia kimberlites (40%). Diamonds classified asirregular (i.e., diamonds with less than half of their crystal facesdeveloped) aremore abundant among the Springfield Basin diamonds(36%) compared to the diamonds from the Eurelia kimberlites (26%).Irregular diamonds were further distinguished based on the presenceor absence of etch marks on fracture surfaces (Table 1). Pseudohe-mimorphic diamonds are present at both locations (Springfield Basin:24 diamond=21%, Eurelia: 5 diamonds=12%, see Fig. 3A,B). Onediamond cube was recovered from the K7 kimberlite at Eurelia.Twenty-one diamonds from the Springfield Basin and eight diamondsfrom Eurelia formed aggregates of two or more individual crystals.Twinning was observed on eleven diamonds from the SpringfieldBasin and three diamonds from the Eurelia area, with most of thediamonds forming macle twins.

The three diamonds from the Echunga goldfield weigh 1.0, 0.84,and 0.46 carat. The two larger diamonds have octahedral shapes withrounded edges; the smallest diamond is a rounded dodecahedron.

3.2. Diamond surface textures

Most of the surface textures, which were classified based onRobinson (1979), are restricted to octahedral or dodecahedral crystalfaces (Table 1). The presence of deep ruts and etch pits on many of thediamonds from the Springfield Basin (41%) and the Eurelia area (51%)causes some of the diamonds to appear brittle (Fig. 4A). The ruts andetch pits are likely caused by exposure of the diamonds to theoxidizing host kimberlite during transport to the Earth's surface.Deformation lamellae (Fig. 4B), which were observed exclusively ondodecahedral crystal faces and are caused by plastic deformation ofthe diamond within the Earth's mantle, were present on 46% of thediamonds from the Springfield Basin and 28% of the diamonds fromEurelia. Less commonly observed surface textures include, e.g.,microdisc patterns (Fig. 4C).

The largest diamond from the Springfield Basin, PBS-01 (“TheSpringfield”), and all three Echunga diamonds exhibit surface texturesthat are diagnostic for abrasion during transport on the Earth's surface.These textures include percussion marks (Fig. 3F) and networkpatterns (Fig. 4D). Percussion marks are the result of the impact of

Fig. 3. A and B: Diamonds with pseudohemimorphic crystal shape from Springfield Basin (A) and K3 kimberlite, Eurelia (B). The diamond from the Springfield Basin exhibits a smallgreen irradiation spot on its surface (arrow). C and D: Diamonds with octahedral crystal shape from Springfield Basin (C) and K7 kimberlite, Eurelia (D). E: Dodecahedral diamondfrom Springfield Basin (FLIN2-18) with brown and green irradiation spots. F: Crescent-shaped percussion marks on the surface of diamond PBS-1, Springfield Basin.

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particles on the diamond surface. These impacts are restricted to highenergyenvironments, such as fastflowing rivers, where transportationallows mineral grains to saltate. Network patterns are caused by thesteady abrasion of the diamond surface and develop typically onplastically deformed dodecahedral diamonds during transport influvial environments (Robinson, 1979).

3.3. Diamond colors

Only a small proportion of the diamonds from the Springfield Basinand the Eurelia area are characterized by intense body colors, withbrown being the most common. Twenty-six diamonds from theSpringfield Basin (21%) and eight diamonds (19%) from the Eureliaarea have an intense brown coloration (Fig. 5). More common,however, are diamonds with a very pale brown tinge. A large portionof the Springfield Basin diamonds (52 diamonds=42%) and of thediamonds from the Eurelia area (17 diamonds=40%) fall in this

category. Thirty diamonds from the Springfield Basin (25%) and 17diamonds (42%) from Eurelia were classified as colorless. Diamondswith a yellow body color are restricted to the Springfield Basin, where14 diamonds (12%) have pale yellow colorations. Yellow diamonds arenot present in the set of diamonds from Eurelia. One diamond fromEurelia is grey. This grey diamond is also the only cube shapeddiamond within the present sample set.

Nineteen diamonds from the Springfield Basin and the two smallerdiamonds from Echunga had green or brown colored surface spots.None of the diamonds from Eureliawas found to have surface spots. Ofthe nineteen Springfield Basin diamonds, sixteen had only greenspots, one had only brown spots, and two had green and brown spots.Green spots were present on both of the Echunga diamonds, but onlythe smallest diamond from Echunga had an additional brown spot.The spots on the diamonds ranged in intensity from pale to dark, andthey are present as single spots and as clusters covering large areas ofthe diamond surface (Fig. 3E, Table 1). Green surface spots form as a

Fig. 4. Secondary electron images of surface textures of diamonds from the Springfield Basin. A: Deep ruts (dotted line), etch marks, and trigons on the surface of diamond FLIN3-11.B: Deformation laminae on a dodecahedral crystal face of diamond FLIN5-18. C: Microdisc patterns on the surface of diamond FLIN4-21. D: Network patterns on a dodecahedralcrystal face of diamond PBS-1.

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result of damage to the diamond surface by α-particle irradiation(Meyer et al., 1965). Irradiation damage on diamonds can occur withinthe host kimberlite, particularly within the upper oxidized zoneswhere radioactive-element enriched groundwater can infiltrate thekimberlite (Harris, 1992). Irradiation spots are also commonlyobserved on the surface of diamonds from placer deposits, wherethey have been attributed to the presence of radioactive minerals(Vance et al., 1973). In this case, irradiation results in the formation of

Fig. 5.Distribution of colors of diamonds from Springfield Basin and Eurelia kimberlites.

green surface spots or clusters of variable color intensities. Becauseirradiation spots are not present on the surface of any diamonds fromthe Eurelia kimberlites, it is likely that the Springfield Basin diamondswere exposed to radioactive minerals, such as detrital zircon, withinthe Springfield Basin itself. Green surface spots may become brownwhen heated to temperatures N500 °C (Vance et al., 1973), which canresult from regional metamorphism or contact metamorphism in thevicinity of a magmatic intrusion. The presence of green and brownsurface spots on the same diamond implies that after an initialirradiation and heating event the diamond was moved to a differentlocation and subsequently received additional irradiation damage.

Fig. 6. Relative frequency of nitrogen concentrations in diamonds from the SpringfieldBasin (dashed line) and diamonds from Eurelia. The Eurelia diamond with the highestnitrogen content (2568 ppm) is not represented.

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3.4. Nitrogen concentrations and aggregation states

The nitrogen concentrations of the diamonds from the SpringfieldBasin and Eurelia range from below the detection limit (Type IIdiamonds) to a maximum of 2853 ppm for a diamond from the K7kimberlite at Eurelia. The concentrations of nitrogen in diamonds fromthe Springfield Basin do not exceed 1820 ppm. The majority of thediamonds from the Springfield Basin (56.6%) and Eurelia (60.5%) havenitrogen concentrations below 100 ppm (Fig. 6). This includes sevendiamonds from the Springfield Basin, which have been classified asType II diamonds (no detectable nitrogen). The distribution ofnitrogen among the nitrogen-rich (N100 ppm) diamonds from theSpringfield Basin is characterized by two discrete modes at 600–700 ppm and at 1100–1200 ppm (Fig. 6).

The aggregation state of the nitrogen impurities in the diamondsfrom the Springfield Basin and Eurelia is variable and ranges from lowaggregation levels, with nitrogen mainly in A-centers (Type IaAdiamonds) to highly aggregated nitrogen (Type IaB diamonds) (Fig. 7).

3.5. UV fluorescence

All diamonds from the Springfield Basin and from Eurelia fluoresceat various intensities in response to UV illumination. The observed UVfluorescence colors include blue, yellow, pink and orange, and green.Eighty-seven diamonds from the Springfield Basin (71%) and twenty-two diamonds from Eurelia (51%) have blue UV fluorescence colors ofvariable intensities and shades (Fig. 8A). The blue UV fluorescencecolor, in most cases, correlates with the presence of nitrogen inelevated aggregation states (Type IaAB and IaB diamonds). However,four blue fluorescing Type IaA diamonds are present (Table 1). YellowUV fluorescence colors (Fig. 8B) were observed on twenty-ninediamonds from the Springfield Basin (24%) and fifteen diamonds fromthe Eurelia area (35%). The shades vary from yellow blue to yellow–

green (Fig. 8C), and yellow–green UV colors are commonly associatedwith diamonds of brown body coloration. Most diamonds with yellowUV fluorescence colors have nitrogen in low aggregation states (TypeIaA diamonds, Type IaAB diamonds with b30% B-centers). Fivediamonds from the Springfield Basin and two diamonds from Eureliahave a yellow fluorescing rim around a blue fluorescing core. Threediamonds, one from the Springfield Basin and two from Eurelia, havepink fluorescing cores, which in all cases are enclosed by a bluefluorescing rim (Fig. 8D). Two diamond fragments from Eurelia (FBS3-01 and FBS3-03) exhibit orange UV fluorescence (Fig. 8E). Based ontheir distinct brown color and very similar nitrogen characteristics, itis likely that these fragments are part of the same diamond. Adistinctive emerald green UV fluorescence color (Fig. 8F) wasobserved on four diamonds from the Springfield Basin. These

Fig. 7. Distribution of nitrogen aggregation states for Springfield Basin and Eureliadiamonds.

diamonds are the three Type IaA diamonds that also have brownradiation spots. The fourth green-fluorescing diamond (SL2-04)contains nitrogen in a highly aggregated state. This diamond alsocontains a high amount of hydrogen.

3.6. Carbon isotopes

The stable carbon isotope compositions (δ13C) of 52 diamondsfrom the Springfield Basin range from −2.8 to −20.0‰ relative to V-PDB (Fig. 9). Most of the Springfield Basin diamonds, however, fallbetween −2 and −10‰. This is similar to the isotopic range of thediamonds from Eurelia (−2.5 to −15.8‰, see Tappert et al., 2009).The distribution of carbon isotope values for diamonds from theSpringfield Basin has amode at−6.5‰, which is similar to the−6.0‰mode of Eurelia diamonds (Fig. 9). Obvious correlations between thephysical characteristics of the diamonds (crystal shape, surfacetextures, colors) and their carbon isotope composition were notobserved.

3.7. Diamond inclusions

The most common inclusion in diamonds from the SpringfieldBasin and from Eurelia is graphite, which occurs as small flakes, oftenalong fractures. One lherzolitic garnet, ∼250 mm in diameter, wasrecovered from diamond FLIN4-11. This garnet has a Cr2O3 content of9.04 wt.%, a CaO content of 7.39 wt.%, and a TiO2 content of 0.26 wt.%(see Table 2). It is compositionally similar to garnet xenocrysts fromkimberlites at Eurelia, which are also predominantly lherzolitic (ScottSmith et al., 1984). Diamond FLIN2-18 contained a ∼50 µm purplish-red inclusion, which was lost during the crushing of the host diamond.This inclusion, which was likely a peridotitic garnet, was the onlyinclusion within any of the brown spotted diamonds from theSpringfield Basin. Ferropericlase inclusions were found in twodiamonds from the Springfield Basin (FLIN5-7, FLIN6-4). In bothcases, multiple individual crystals were recovered, ranging in sizefrom around 30 to 100 µm. The ferropericlase inclusions in bothdiamonds are compositionally similar, with Mg-numbers in the range85–86, and NiO contents of 1.25–1.47 wt.% (Table 2). An additionalcrystal with olivine stoichiometry has been identified in diamondFLIN5-07 as a small (b20 µm) inclusion fragment, which was exposedon a diamond cleavage surface after crushing. Because of its small sizeit was not possible to recover the inclusion for polishing. Therefore,only a poor quality in-situ analysis could be attained (Table 2).

The composition of the ferropericlase inclusions from the SpringfieldBasin diamonds is almost identical to the ferropericlase inclusions indiamonds from the Eurelia kimberlites, for which a sublithospheric,possibly lower mantle origin has been established based on theirassociation with MgSiPvk (Tappert et al., 2009; Table 2). An inclusionwith olivine stoichiometry, similar to the one in the Springfield Basindiamond FLIN5-07, was also found in diamond FBS5-12 from Eurelia(Table 2). Even though theolivine-bearingdiamond fromEurelia did notcontain additional ferropericlase, a possible sublithospheric origin forthis diamond has been inferred based on its low-nitrogen concentrationand high nitrogen aggregation states (Tappert et al., 2009).

4. Discussion

4.1. Springfield Basin and Eurelia: a comparison

The physical characteristics (crystal shape, color, and surfacetextures) of the placer diamonds from the Springfield Basin resemblethose of the diamonds from the Eurelia kimberlites (Figs. 3 and 5).Both have a high abundance of diamonds with pseudohemimorphicshapes, pale brown coloration, and deep ruts or etch pits (Table 1).Diamonds from both deposits also have similar nitrogen character-istics. They have a high abundance of low-nitrogen (b100 ppm)

Fig. 8. Fluorescence colors of diamonds from the Springfield Basin and Eurelia kimberlites. A: Blue fluorescence (FLIN4-13, Springfield Basin) B: Yellow fluorescence (FBS5-01, K7kimberlite, Eurelia) C: Yellow–green fluorescence (FBS5-09, K7 kimberlite, Eurelia) D: Blue fluorescing rim with pink fluorescing core (FBS3-08, 41C kimberlite, Eurelia) E: Orangefluorescence (FBS3-01, 41C kimberlite, Eurelia) F: Green fluorescence (FLIN2-02, Springfield Basin).

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diamonds, which have variable nitrogen aggregation states (Fig. 10).The carbon stable isotope compositions of the diamonds from theSpringfield Basin and Eurelia have similar ranges, and a similardistribution of isotope values (Fig. 9). The modes of δ13C values ofaround −6.0‰ in both deposits distinguishes the South Australiandiamonds from other diamond populations worldwide, whichcommonly have δ13C modes of around −5.0 to −4.0‰ (Deines,1980; Cartigny et al., 1998). Diamonds with isotopic modes of around−5.0 to −4.0‰ are usually linked to primordial carbon reservoirswithin the upper mantle (Deines, 2002).

A small portion of the diamonds from the Springfield Basin and fromEurelia has an isotopically light composition, with δ13C values rangingfrom −8.5 to −20‰ (Fig. 9). Diamonds with similarly light composi-tions have been identified in numerous other deposits worldwide,

where they are almost exclusively associated with eclogitic inclusionassemblages (Sobolev et al., 1979; Kirkley et al., 1991). It is possible thateclogitic sources were also involved in the formation of the isotopicallylight diamonds from South Australia, but at this point it cannot beproven, because of the lack ofmineral inclusions in these diamonds. Thenature of the isotopically light carbon reservoirs for eclogitic diamonds iscontroversial; it has been proposed that low δ13C values of diamondsreflect fractionated mantle carbon (Cartigny et al., 2001), but othermodels favor the involvementof subducted organicmatter,which is alsoisotopically light (Frank, 1969; Sobolev and Sobolev, 1980).

Strong evidence for a close relationship between the diamondpopulations from the Springfield Basin and Eurelia comes from thepresence of ferropericlase-bearing mineral inclusion assemblages indiamonds from each area. Ferropericlase has been identified as an

Fig. 9. Carbon stable isotope composition (δ13C) of diamonds from the Springfield Basin(A) and Eurelia kimberlites (B).

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inclusion in diamonds from several deposits in the world, but itsoccurrence is generally restricted to a small number (b5) of diamonds(Liu, 2002). Only some diamond deposits in western Brazil, includingthe São Luiz/Juina area, and in the Kankan district in Guinea haveyielded a larger number of diamonds (N15) with ferropericlaseinclusions (Wilding, 1990; Harte and Harris, 1994; Hutchison, 1997;Harte et al., 1999; Stachel et al., 2000; Kaminsky et al., 2001; Bulanovaet al., 2008; Kaminsky et al., this issue). The presence of ferropericlase

Table 2Composition of mineral inclusions in diamonds from South Australia (given in weight perce

Deposit Springfield Basin

DiamondID

FLIN4-11

FLIN5-07

FLIN5-07

FLIN5-07

FLIN5-07

FLIN5-07

FLIN5-07

FLIN6-04

Mineral Garnet Fper Fper Fper Fper Fper Olivinea Fper

P2O5 0.03 ≤0.01 ≤0.01 0.02 ≤0.01 0.02 0.01 ≤0.01SiO2 40.44 ≤0.01 ≤0.01 0.03 0.02 0.02 44.85 0.03TiO2 0.26 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.02 ≤0.01Al2O3 16.09 0.04 ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.04 0.03Cr2O3 9.04 0.31 0.16 0.15 0.19 0.14 0.00 0.50MgO 19.15 73.74 75.19 76.67 73.16 74.97 55.76 74.81CaO 7.39 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.04 ≤0.01MnO 0.39 0.17 0.17 0.17 0.13 0.18 0.13 0.17FeO 6.79 23.60 22.28 22.75 23.25 23.03 4.91 22.02NiO 0.02 1.47 1.29 1.25 1.25 1.45 0.12 1.21Na2O ≤0.02 0.03 ≤0.02 0.03 0.00 ≤0.02 0.00 0.03K2O ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.01 ≤0.01 0.00 ≤0.01Total 99.6 99.4 99.1 101.1 98.0 99.8 105.9 98.8Mg# 83.4 84.8 85.7 85.7 84.9 85.3 95.3 85.8

Abbreviations: Fper—ferropericlase, MgSiPer—MgSi perovskite.a Poor quality in-situ analysis.

inclusions is an indicator of an unusual deep origin for a diamond,because ferropericlase, in a typical peridotitic mantle environment(pyroxene saturated under upper mantle conditions), is only stable atpressures greater than around 25 Gpa, which corresponds to a depthof N650 km (Liu, 1975, 1976b). This is considerably deeper than theestimated depth of origin for the vast majority of diamonds world-wide, which is in the range 140–250 km (e.g. Boyd and Gurney, 1986;Meyer, 1987; Stachel and Harris, 1997). Ferropericlase is one of themain mineral constituents of the lower mantle, along with magne-sium silicon oxide (MgSiO3), which is compositionally equivalent withenstatite, but at pressure conditions of the lower mantle hasperovskite structure (MgSiPvk) (Liu, 1976a). Unlike the presence offerropericlase as a single inclusion mineral, which theoretically canform in chemically unusual environments in the upper mantle (Breyet al., 2004), the occurrence of ferropericlase together with MgSiO3

(MgSiPvk or retrograde enstatite) in the same diamond, is generallyregarded as proof for their lower mantle origin.

The possibility of a lower mantle origin for diamonds from Eurelia(also referred to as “Orroroo”) has previously been suggested by ScottSmith et al. (1984), based on findings of two diamonds withferropericlase inclusions, and one diamond with an inclusion ofMgSiO3-stoichiometry. Because the ferropericlase and MgSiO3 inclu-sions, in this case, were not only recovered from different diamonds,but also from different kimberlite dykes, it could not be establishedthat the inclusions formed in equilibrium, and hence were of lowermantle origin. In addition, the relatively high nickel content of theMgSiO3 inclusion (0.13 wt.% NiO) suggests an upper mantle origin,since MgSiO3 inclusions from the lower mantle generally have nickelcontents of b0.05 wt.% NiO (Stachel et al., 2000). More robustevidence for a lower mantle origin of the Eurelia diamonds waspresented by Tappert et al. (2009), who recovered the diagnosticferropericlase–MgSiO3 assemblage within a diamond from the K7kimberlite at Eurelia. In this case, the low-nitrogen concentration andthe high aggregation state of nitrogen of the host diamond supportedthe inclusions evidence for a lower mantle origin.

The ferropericlase inclusions from the two Springfield Basindiamonds FLIN5-7 and FLIN6-4 are compositionally (Mg#: 85–86,NiO: 1.17–1.47 wt.%, Cr2O3: 0.11–0.62 wt.%) indistinguishable from theferropericlase inclusions in diamonds from the Eurelia area (Table 2).In addition, both diamonds have low concentrations of nitrogenimpurities, which are present in highly aggregated states (FLIN5-7:22.9 ppm, 86%B; FLIN6-4: 8.2 ppm N, 98%B; Table 1). The nitrogencharacteristics of the two Springfield Basin diamonds is consistentwith the nitrogen data for the ferropericlase-bearing diamonds from

nt).

Eurelia kimberlite K7

FLIN6-04

FBS5-11 FBS5-11

FBS5-11

FBS5-11

FBS5-11

FBS5-11

FBS5-11

FBS5-12

Fper MgSiPer Fper Fper Fper Fper Fper Fper Olivine

≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.02 ≤0.01 0.02 ≤0.010.03 60.02 0.02 0.02 ≤0.01 ≤0.01 0.02 ≤0.01 40.780.02 0.03 0.02 0.03 0.02 ≤0.01 ≤0.01 ≤0.01 0.02

≤0.01 0.25 ≤0.01 ≤0.01 ≤0.01 0.02 ≤0.01 ≤0.01 ≤0.010.62 0.38 0.14 0.26 0.18 0.21 0.19 0.18 0.07

75.81 36.58 73.96 74.04 73.88 73.57 73.62 75.14 48.81≤0.01 0.05 0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 0.060.17 0.15 0.14 0.17 0.20 0.21 0.19 0.21 0.11

22.16 2.93 23.78 23.57 23.12 23.59 23.11 23.33 8.451.17 0.09 1.16 1.26 1.16 1.19 1.40 1.12 0.470.04 ≤0.02 ≤0.02 0.03 0.03 ≤0.02 ≤0.02 ≤0.02 ≤0.02

≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01100.1 100.5 99.3 99.4 98.6 98.8 98.6 100.0 98.885.9 95.7 84.7 84.8 85.1 84.8 85.0 85.2 91.1

Fig. 10. Concentration of nitrogen impurities versus aggregation states of nitrogen (givenas percentage of higher aggregated B-centers relative to A-centers) in diamonds from theSpringfield Basin and from Eurelia kimberlites. Dotted lines represent isochrones for anassumed residence temperature of 1200 °C; calculated after Taylor et al. (1990).

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the Eurelia area, which provides evidence for the sublithosphericorigin of the Springfield Basin diamonds and reinforces the observedsimilarities between the diamond populations of the two areas.

The physical and compositional similarities between the bulk ofthe placer diamonds from the Springfield Basin and the diamondsfrom kimberlites at Eurelia suggests that the Springfield Basindiamonds are derived from kimberlitic sources that resemble or areidentical with the Eurelia kimberlites. Additional support for thisinterpretation comes from the presence of abundant diamondindicator minerals in the Springfield Basin, which suggests proximalkimberlitic sources. However, the emplacement age of the kimberlitesat Eurelia is generally considered to be Jurassic, based on two identicalU–Pb ages for zircons of 170 Ma from the K3 and K5 kimberlites (ScottSmith et al., 1984), and therefore younger than the proposed Permian

age of the conglomerates in the Springfield Basin. Contrary to thenotion of proximal kimberlitic sources, this would indicate that theEurelia kimberlites are not the direct source of the diamonds in theSpringfield Basin. However, since age determinations are restricted toonly two of the kimberlite dykes at Eurelia, it cannot be excluded thatan older kimberlite generation at Eurelia exists. Differences in thedistribution of mantle-derived xenocrysts in kimberlites from Eurelia,noted by Scott Smith et al. (1984), may reflect such differentkimberlite age groups. Alternatively, the Springfield Basin diamondsmay be derived from undiscovered Permian or pre-Permian kimber-lites outside the Eurelia area. Inaccuracies in the estimates of thedepositional ages of the conglomerates in the Springfield Basinmay beanother explanation for the discrepancy to the emplacement ages ofthe known kimberlites. If the conglomerates in the Springfield Basinwere ∼80–100 million years younger than previously suggested, theEurelia kimberlites could be the direct source of the diamonds withinthese conglomerates. Additional information about the emplacementages of the kimberlites at Eurelia, and further constraints on thedeposition ages of the conglomerates in the Springfield Basin mayresolve the current age discrepancy.

4.2. The old diamonds of the Springfield Basin

Three diamonds from the Springfield Basin (FLIN2-02, FLIN2-18,PBS-1) are distinct from all other diamonds at this location and fromthe Eurelia diamonds. These diamonds have brown irradiation spotson their surfaces. They also have pale yellow colors in combinationwith an emerald green UV fluorescence, which is possibly caused bythe presence of nitrogen as H3 centers (Davies, 1977). All threediamonds contain similar concentrations of nitrogen (417–594 ppm),with nitrogen in low aggregation states (Type IaA diamonds). Thesediamonds have well-developed dodecahedral crystal shapes (Fig. 2E),a small number of inclusions, and are relatively large in size. Theyaccount for ∼20% of the weight of the entire sample set from theSpringfield Basin. The presence of abrasion textures (percussionmarks, network patterns) on the surface of diamond PBS-1 (Fig. 4D)indicates that the diamonds are derived from distal kimberliticsources. These kimberlitic sources must be much older than deposi-tional ages of the conglomerates in the Springfield Basin, because thepresence of brown irradiation spots provides evidence that thesediamonds experienced at least one cycle of irradiation, followed by ametamorphic overprint at temperature N500 °C (Vance et al., 1973),before being deposited in the Springfield Basin. Based on the observedpurple-reddish, likely peridotitic garnet inclusion in one of thesediamonds (FLIN2-18), these older diamonds probably formed in aperidotitic environment within the lithospheric upper mantle, whichis the source for the majority of diamonds worldwide (Sobolev, 1977;Gurney,1984; Meyer, 1987). In accordancewith that, the carbon stableisotope values of two of the “old” diamonds (−4.7 and−6.4‰) are inthe range of typical peridotitic diamonds worldwide (Sobolev et al.,1979; Cartigny et al., 1998). The low-nitrogen aggregation states(≤1.8% B-centers) of all three diamonds also indicate that they formedin an environment with a low geothermal gradient, which is typicalfor ancient cratonic lithosphere (c.f., Pollack and Chapman, 1977). Ifthe diamonds formed in a lithosphere with an elevated geothermalgradient, such as the one beneath the Adelaide Fold Belt (Tappertet al., 2007), their mantle residencewould have had to be rather short,in order to preserve their low-nitrogen aggregation states. However,the high quality of these diamonds is not consistent with rapid growthand subsequent exhumation during initiation of a kimberlite event.The “old” diamonds from the Springfield Basin are morphologicallysimilar to the placer diamonds from the Echunga goldfield. Bothgroups of diamonds are well crystallized, are of relatively large sizeand, more importantly, exhibit brown irradiation spots and abrasiontextures. These physical similarities suggest that the old SpringfieldBasin diamonds and the Echunga diamonds may not only be derived

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from a common, intermediate, sedimentary source, but even from thesame distal kimberlitic sources.

4.3. Sources of the “old” Springfield Basin and Echunga diamonds

The conglomerates in the Springfield Basin are interpreted to beremnants of Permian glacial deposits, or slightly younger deposits oflocally derived, reworked Permian glacial sediments (Drexel andPreiss, 1995). The diamond indicator minerals within the conglomer-ates are most likely derived from local kimberlitic sources and linkedto the abundant “younger” diamonds of the Springfield Basin. It seemsunlikely that any of the indicator minerals in the Springfield Basin arerelated to the “old” diamonds, considering their long history oftransport and metamorphism. These three diamonds may solelyrepresent rare and exotic components of the Permian glacial detritus.

Although the diamonds from Echunga were recovered fromconglomerates of Tertiary age (Ludbrook, 1980), these conglomeratesare likely to contain components of reworked Permian glacigenesediments, which as remnants are present in many parts of theSouthern Mount Lofty Ranges, just outside the Echunga area. Like the“old” diamonds from the Springfield Basin, the Echunga diamonds,therefore, may simply be part of the glacial detritus, transported toSouth Australia by Permian glaciers.

Althoughmuch of the Permian sedimentary record in the AdelaideFold Belt and in the adjacent Mount Lofty Ranges has been erased byerosion, as a result of Neogene uplift (Sprigg, 1945; Sandiford, 2003and references therein), equivalent Permian glacial deposits arepreserved in many other parts of southern Australia (Crowell andFrakes,1971). These Permian glacial sequences reflect the globally coolclimatic conditions during the Early Permian (Frakes et al., 1992), andthe high latitude position of Australia, which at that time formed partof the supercontinent Gondwana (Irving and Green, 1958) (Fig. 11).

Fig. 11. Reconstruction of eastern Gondwana during Permo-Carboniferous glaciation, showing upfrom Crowell and Frakes (1971) and Veevers et al. (1994). Locations of additional alluvial diamo

Equivalents of the Permian glacigene sediments of southern Australiaare also widespread in other parts of the former Gondwana super-continent, e.g., the Dwyka-Group in Southern Africa (Du Toit, 1921;Visser, 1983), and the Itararé Subgroup in South America (Rocha-Campos and Santos, 1981). In some regions, these sediments arerecognized as intermediate sources for alluvial diamond deposits(Harger, 1909; Tompkins and Gonzaga, 1989; Gonzaga et al., 1994).Within Australia, some of the alluvial diamonds from New SouthWales were also interpreted to be derived from Permian glacigenesequences (Davies et al., 1999; Davies et al., 2002). Like the “old”Springfield Basin and Echunga diamonds, some of the New SouthWales diamonds also show abrasion textures and brown irradiationspots on their surfaces (Davies et al., 1999), which suggests a directconnection between these diamonds, and similar, if not identicalprimary sources.

Based on indicators for the direction of ice movement during thePermian glaciations in southern Australia (Crowell and Frakes, 1971),much of the sedimentary material, including the diamonds, may bederived from sources in the eastern part of Antarctica, which duringthe Permian was directly connected to southern Australia (Fig. 11). Inthis case, the primary kimberlitic sources of the diamonds may belocated on the East Antarctic Craton. However, the diamonds may alsobe derived from intermediate sources, such as metamorphosedsedimentary rocks.

5. Conclusions

The bulk of the placer diamonds from the Springfield Basinresembles the diamonds from kimberlites at Eurelia. Diamonds fromboth areas have a similar distribution of crystal shapes, body colors, andsurface textures. Particularly prominent are the high abundance ofdiamonds with pseudohemimorphic shape, diamonds with pale brown

lands as source regions of glacial sediments, and sedimentary transport directions;modifiednd occurrences in New South Wales from Davies et al. (1999) and Davies et al. (2002).

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bodycoloration, and the commonpresence of deep ruts and etch pits ondiamond surfaces. In both areas, themajority of diamonds are nitrogen-poor, with nitrogen contents b100 ppm. Similarities also exist in thestable carbon isotope composition of the diamonds;with both diamondpopulations having a similar distribution of δ13C values and a markedδ13C mode at around−6‰. The presence of ferropericlase as inclusionsin diamonds from the Springfield Basin provides another link to thediamonds from the Eurelia area, where similar inclusions in diamondsoccur, and provides evidence for the sublithospheric origin of at leastpart of the SpringfieldBasindiamondpopulation. Theoverall similaritiesbetween the Springfield Basin and Eurelia diamondpopulations suggestthat most of the Springfield Basin diamonds are derived from nearbyprimary sources,which closely resemble the kimberlite dykes at Eurelia.Jurassic ages determined for two Eurelia kimberlites appear to contra-dict an origin of Permian Springfield Basin diamond deposits from theseprimary sources. However, the distinct possibility that protractedkimberlite activity in the area overlapped with Permian sedimentationexists, and the strong similaritywith the younger Eurelia diamonds thenwould simply reflect repeated tapping of similar/identical diamondsources in the lithospheric and sublithospheric mantle over time.

Despite their overall similarities, three diamonds from the Spring-field Basin are distinct from the Eurelia diamonds and all otherSpringfield Basin diamonds. These diamonds are characterized byrelatively large sizes, well-developed crystal shapes, yellow bodycolorations, and the presence of brown irradiation spots on theirsurfaces, which indicate that the diamonds are much older than otherdiamonds in the Springfield Basin. The presence of abrasion textures onthe surface of one of the diamonds is consistentwith that interpretation,and indicates that these diamonds have been transported considerabledistances away from their original kimberlitic sources. Similarities intheir physical characteristics possibly link these three “old” SpringfieldBasin diamonds with placer diamonds from the Echunga area, around350 km south. In both cases, the local sources of the diamonds wereprobably fluvio-glacial sedimentary rocks of Permian age, which in partwere reworked into younger sediments. Based on palaeo-transportdirections of the Permian glacial sediments, the diamonds were mostlikely derived from intermediate sedimentary, or primary kimberliticsources on the East Antarctic craton. A similar origin may also apply topart of the placer diamonds from New South Wales.

Acknowledgements

We are grateful to Allan Pring (South Australian Museum) forproviding access to diamond from the Echunga goldfield. Funding wasprovided by the Australian Research Council (ARC), the Department ofPrimary Industries and Resources South Australia (PIRSA), andFlinders Diamonds Ltd. Reviews by Lynton Jaques and an anonymousreviewer are gratefully acknowledged.

ReferencesAmtsberg, H., 1969. A contribution to the mesophytic flora of South Australia.

Transactions of the Royal Society of South Australia 93, 79–85.Atkinson, W.J., Smith, C.B., Danchin, R.V., Janse, A.J.A., 1990. Diamond deposits of

Australia. In: Hughes, F.E. (Ed.), Geology of the Mineral Deposits of Australia andPapua New Guinea. Australasian Institute of Mining and Metallurgy, Melbourne,pp. 69–76.

Boyd, F.R., Gurney, J.J., 1986. Diamonds and the African lithosphere. Science 232, 472–477.Boyd, S.R., Kiflawi, I., Woods, G.S., 1994. The relationship between infrared absorption and

the A defect concentration in diamond. Philosophical Magazine Part B 69, 1149–1153.Boyd, S.R., Kiflawi, I., Woods, G.S., 1995. Infrared absorption by the B nitrogen aggregate

in diamond. Philosophical Magazine Part B 72, 351–361.Brey, G.P., Bulatov, V., Girnis, A., Harris, J.W., Stachel, T., 2004. Ferropericlase — a lower

mantle phase in the upper mantle. Lithos 77, 655–663.Bulanova, G.P., Smith, C.B., Kohn, S.C., Walter, M.J., Gobbo, L., Kearns, S., 2008. Machado

River, Brazil— a newly recognised ultradeep diamond occurrence. 9th InternationalKimberlite Conference. Extended Abstract No. 9IKC-A-00233.

Cartigny, P., Harris, J.W., Phillips, D., Girard, M., Javoy, M., 1998. Subduction-relateddiamonds? The evidence for a mantle-derived origin from coupled 13C–15Ndeterminations. Chemical Geology 147, 147–159.

Cartigny, P., Harris, J.W., Javoy, M., 2001. Diamond genesis, mantle fractionations andmantle nitrogen content: a study of δ13C–N concentrations in diamonds. Earth andPlanetary Science Letters 185, 85–98.

Colchester, D.M., 1972. A preliminary note on kimberlite occurrences in South Australia.Journal of the Geological Society of Australia 19, 383–386.

Coplen, T.B., Kendall, C., Hopple, J., 1983. Comparison of stable isotope referencesamples. Nature 302, 236–238.

Crowell, J.C., Frakes, L.A., 1971. Late Paleozoic glaciation of Australia. Journal of theGeological Society of Australia 17, 115–155.

Davies, G., 1977. The H3 centre. Diamond Research 1977, 15–24.Davies, R.M., O'Reilly, S.Y., Griffin, W.L., 1999. Diamonds fromWellington, NSW: insights into

the origin of eastern Australian diamonds. Mineralogical Magazine 63, 447–471.Davies, R.M., O'Reilly, S.Y., Griffin, W.L., 2002. Multiple origins of alluvial diamonds from

New South Wales, Australia. Economic Geology 97, 109–123.Deines, P.,1980. Thecarbon isotopic compositionofdiamonds: relationship todiamondshape,

color, occurrenceandvaporcomposition.GeochimicaetCosmochimicaActa44,943–961.Deines, P., 2002. The carbon isotope geochemistry of mantle xenoliths. Earth Science

Reviews 58, 247–278.Drexel, J.F., Preiss, W.V., (Eds.). The geology of South Australia. Vol. 2, The Phanerozoic

South Australia. Geological Survey, 1995 Bulletin vol. 54, 347 pp.Du Toit, A.L., 1921. The Carboniferous glaciation of South Africa. Transactions of the

Geological Society of South Africa 24, 188–227.Ferguson, J., Sheraton, J.W., 1979. Petrogenesis of kimberlitic rocks and associated

xenoliths of southeastern Australia. In: Boyd, F.R., Meyer, H.O.A. (Eds.), Kimberlites,Diatremes, and Diamonds: Their Geology, Petrology and Geochemistry. AmericanGeophysical Union, pp. 140–160.

Frakes, L.A., Francis, J.E., Syktus, J.I., 1992. Climate Modes of the Phanerozoic. CambridgeUniversity Press. 286 pp.

Frank, F.C., 1969. Diamonds and deep fluids in the upper mantle. In: Runcorn, S.K. (Ed.), TheApplicationofModernPhysics to theEarth's andPlanetary Interiors. InWiley,pp. 247–250.

Gommers, F.L., 1988. Diamonds from the Echunga Goldfield, South Australia. Records ofthe South Australian Museum, 22, 131–138.

Gonzaga, G.M., Teixeira, N.A., Gaspar, J.C., 1994. The origin of diamonds in WesternMinas Gerais, Brazil. Mineralium Deposita 29, 414–421.

Gurney, J.J., 1984. A correlation between garnets and diamonds in kimberlites. In:Glover, J.E., Harris, P.G. (Eds.), Kimberlite Occurrence and Origin: a Basis forConceptual Models in Exploration, vol. 8. Geology Department and UniversityExtension, University of Western Australia, pp. 143–166. Special Publication.

Harger, H.S., 1909. The occurrence of diamonds in Dwyka conglomerate andamygdaloidal lavas; and the origin of the Vaal River diamonds. Transactions ofthe Geological Society of South Africa 12, 139–158.

Harris, J.W., 1992. Diamond geology. In: Field, J.E. (Ed.), The Properties of Natural andSynthetic Diamond. Academic Press, London. 710 pp.

Harte, B., Harris, J.W., 1994. Lower mantle associations preserved in diamonds.Mineralogical Magazine 58A, 384–385.

Harte, B., Harris, J.W., Hutchison, M.T., Watt, G.R., Wilding, M.C., 1999. Lower mantlemineral associations in diamonds from Sao Luiz, Brazil. In: Fei, Y., Bertka, C.M.,Mysen, B.O. (Eds.), Mantle Petrology: Field Observations and High PressureExperimentation: a Tribute to Francis R. (Joe) Boyd. The Geochemical Society,Houston, pp. 125–153. Special Publication.

Hutchison, M.T., 1997. Constitution of the deep transition zone and lower mantle shownby diamonds and their inclusions. PhD Thesis, University of Edinburgh, 306 pp.

Irving, E., Green, R., 1958. Polar movement relative to Australia. Geophysical JournalInternational 1, 64–72.

Kaminsky, F.V., Zakharchenko, O.D., Davies, R.M., Griffin, W.L., Khachatryan-Blinova, G.K., Shiryaev, A.A., 2001. Superdeep diamonds from the Juina area, Mato GrossoState, Brazil. Contributions to Mineralogy and Petrology 140, 734–753.

Kaminsky, F.V., et al., 2009. Super-deep diamonds from kimberlites in the Juina area,Mato Grosso State, Brazil. Proceedings of the 9th International KimberliteConference. Lithos 112S, 833–842 (this issue).

Kirkley, M.B., Gurney, J.J., Otter, M.L., Hill, S.J., Daniels, L.R., 1991. The application of Cisotope measurements to the identification of the sources of C in diamonds — areview. Applied Geochemistry 6, 477–494.

Liu, L.G., 1975. Post-oxide phases of forsterite and enstatite. Geophysical ResearchLetters 2, 417–419.

Liu, L.G., 1976a. The high pressure phases of MgSiO3. Earth and Planetary Science Letters31, 200–208.

Liu, L.G., 1976b. Orthorhombic perovskite phases observed in olivine, pyroxene, andgarnet at high pressures and temperatures. Physics of the Earth and PlanetaryInteriors 11, 289–298.

Liu, G., 2002. An alternative interpretation of lower mantle mineral associations indiamonds. Contributions to Mineralogy and Petrology 144, 16–21.

Ludbrook, N.H., 1980. A guide to the geology and mineral resources of South Australia.South Australian Department of Mines and Energy, Handbook. 230 pp.

Meyer, H.O.A., 1987. Inclusions in diamond. In: Nixon, P.H. (Ed.), Mantle Xenoliths.Wiley, pp. 501–522.

Meyer, H.O.A., Milledge, H.J., Nave, E., 1965. Natural irradiation damage in Ivory Coastdiamonds. Nature 206, 392.

Pollack, H.N., Chapman, D.S., 1977. On the regional variation of heat flow, geotherms,and lithospheric thickness. Tectonophysics 38, 279–296.

Robinson, D.N., 1979. Surface textures and other features of diamonds. PhD Thesis,University of Cape Town, 221 pp.

Rocha-Campos, A.C., Santos, P.R., 1981. The Itararé Subgroup, Aquidauana Group and SanGregório Formation, Paraná Basin, southeastern South America. In: Hambrey, M.J.,Harland, W.B. (Eds.), Earth's Pre-Pleistocene Glacial Record. Cambridge UniversityPress, pp. 842–852.

821R. Tappert et al. / Lithos 112S (2009) 806–821

Runciman, W.A., Carter, T., 1971. High resolution infra-red spectra of diamond. SolidState Communications 9, 315–317.

Sandiford, M., 2003. Neotectonics of southeastern Australia: linking the Quaternaryfaulting record with seismicity and in situ stress. In: Hillis, R.R., Müller, D. (Eds.),Evolution and Dynamics of the Australian Plate. Geological Society of Australia,Special Publication, pp. 101–113.

Scott Smith, B.H., Danchin, R.V., Harris, J.W., Stracke, K.J., 1984. Kimberlites near Orroroo,South Australia. In: Kornprobst, J. (Ed.), Kimberlites I: Kimberlites and RelatedRocks. Elsevier, Amsterdam, pp. 121–142.

Sobolev, N.V., 1977. Deep-seated Inclusions in Kimberlites and the Problem of theComposition of the Upper Mantle. American Geophysical Union (Translated fromthe Russian edition, 1974), 279 pp.

Sobolev, V.S., Sobolev, N.V., 1980. New proof of submersion to great depths of eclogitizedrocks of the earth's crust. Doklady Akademii Nauk SSSR 250, 683–685.

Sobolev, N.V., Galimov, E.M., Ivanovskaya, I.N., Yefimova, E.S., 1979. Isotope compositionof carbon of diamonds containing crystalline inclusions. Doklady Akademii NaukSSSR 249, 1217–1220.

Sprigg, R.C., 1945. Some aspects of the geomorphology of a portion of the Mount LoftyRanges. Transactions of the Royal Society of South Australia 69, 277–304.

Stachel, T., Harris, J.W., 1997. Syngenetic inclusions in diamond from the Birim field(Ghana)— a deep peridotitic profile with a history of depletion and re-enrichment.Contributions to Mineralogy and Petrology 127, 336–352.

Stachel, T., Harris, J.W., Brey, G.P., Joswig, W., 2000. Kankan diamonds (Guinea) II: lowermantle inclusion parageneses. Contributions to Mineralogy and Petrology 140, 16–27.

Stracke, K.J., Ferguson, J., Black, L.P., 1979. Structural setting of kimberlites in southeasternAustralia. In: Boyd, F.R., Meyer, H.O.A. (Eds.), Kimberlites, Diatremes, and DiamondsVolume 1: Their Geology, Petrology and Geochemistry. Proceedings of the 2ndInternational Kimberlite Conference. American Geophysical Union, pp. 71–91.

Tappert, R., Foden, J., Wills, K., Goryniuk, M.C., 2007. Geochemical variability within thelithospheric mantle beneath the Adelaide Fold Belt, South Australia. Geochimica etCosmochimica Acta 71, A1004.

Tappert, R., Foden, J., Stachel, T., Muehlenbachs, K., Tappert, M., Wills, K., 2009. Deepmantle diamonds from South Australia: a record of Pacific subduction at theGondwanan margin. Geology, 37, 43–46.

Taylor, W.R., Jaques, A.L., Ridd, M., 1990. Nitrogen-defect aggregation characteristics ofsome Australasian diamonds — time–temperature constraints on the sourceregions of pipe and alluvial diamonds. American Mineralogist, 75, 1290–1310.

Tompkins, L.A., Gonzaga, G.M., 1989. Diamonds in Brazil and a proposed model for theorigin and distribution of diamonds in the Coromandel region, Minas Gerais, Brazil.Economic Geology 84, 591–602.

Vance, E.R., Harris, J.W., Milledge, H.J., 1973. Possible origins of a-damage in diamondsfrom kimberlite and alluvial sources. Mineralogical Magazine 39, 349–360.

Veevers, J.J., Powell, C.M., Collinson, J.W., Lopez-Gamundf, O.R., 1994. Synthesis. In:Veevers, J.J., Powell, C.M. (Eds.), Permian–Triassic Pangean Basins and FoldbeltsAlong the Panthalassan Margin of Gondwanaland. Geological Society of AmericaMemoir, Boulder, Colorado, pp. 331–353.

Visser, J.N.J., 1983. An analysis of the Permo-Carboniferous glaciation in the marineKalahari Basin, Southern Africa. Palaeogeography, Palaeoclimatology, Palaeoecol-ogy 44, 295–315.

Wilding, M.C., 1990. Untitled PhD thesis Thesis, University of Edinburgh, 281 pp.Wyatt, B.A., Shee, S.R., Griffin, W.L., Zweistra, P., Robison, H.R., 1994. The petrology of the

Cleve kimberlite, Eyre peninsula, South Australia. In: Meyer, H.O.A., Leonardos, O.H.(Eds.), Kimberlites, Related Rocks andMantle Xenoliths. CPRMSpecial Publication,pp. 62–79.