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Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

Type I eclogites from Roberts Victor kimberlites: Productsof extensive mantle metasomatism

Yoann Greau a,b,c,⇑, Jin-Xiang Huang a,b,d, William L. Griffin a,b, Christophe Renac e,Olivier Alard a,c, Suzanne Y. O’Reilly a,b

a ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Dept. of Earth and Planetary Sciences,

Macquarie University, NSW 2109, Australiab ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), Dept. of Earth and Planetary Sciences, Macquarie University,

NSW 2109, Australiac Geosciences Montpellier, CNRS UMR-5243, Equipe Manteau et Interfaces, Universite Montpellier II, France

d School of Earth Sciences and Resources, China University of Geosciences, Beijing, Chinae Laboratoire Transfert des Fluides Magmatiques, Universite Jean Monnet, Saint-Etienne, France

Received 1 February 2011; accepted in revised form 22 August 2011; available online 31 August 2011

Abstract

Type I and Type II eclogite xenoliths from the Roberts Victor kimberlite (South Africa) show marked differences in termsof microstructures, mineralogy, major- and trace-element compositions and oxygen-isotope compositions. The unequilibratedmicrostructures of Type I eclogites, their typical accessory assemblages (phologopite, diamond, sulphides, fluid inclusions)and the ubiquitous presence of “melt pockets” in garnets provide strong evidence of metasomatism. Type II eclogites system-atically lack such features and are microstructurally more equilibrated. Type I eclogites are more magnesium-rich than mostType II (mean Mg# = 0.56 vs. 0.46), while Type II eclogites are generally more Ca-rich (mean CaO = 9 vs. 12 wt%) and Fe-rich (mean FeO = 10 vs. 12 wt%). Type I eclogites are systematically enriched in LREE, Sr, Ba, alkali elements, HFSE, Thand U compared to the more depleted Type II eclogites. Calculated trace-element patterns of fluids in equilibrium with Type Ieclogites are closely similar to those of volatile-rich small-volume mantle melts in the carbonatite–kimberlite spectrum com-monly inferred to be responsible for mantle metasomatism. Although oxygen isotopes are often used to argue for a subduc-tion origin of mantle eclogites, correlations between d18O of garnet and typical metasomatic tracers suggest that themetasomatic process also has shifted the oxygen-isotope compositions of the Type I eclogites toward heavier values. RobertsVictor Type I eclogites thus carry the imprint of a metasomatic process that strongly modified their major-element, trace-ele-ment and isotopic compositions, while the more pristine Type II eclogites escaped this modification. Therefore, attempts toconstrain the origin of Roberts Victor eclogites should not be based on the much more abundant Type I eclogites, whichretain little geochemical memory of their protoliths. The most suitable materials for such investigations may be the less meta-somatised, but more rare, Type II eclogites.� 2011 Elsevier Ltd. All rights reserved.

0016-7037/$ - see front matter � 2011 Elsevier Ltd. All rights reserved.

doi:10.1016/j.gca.2011.08.035

⇑ Corresponding author at: ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Dept. ofEarth and Planetary Sciences, Macquarie University, Building E7A, Room 430, NSW 2109, Australia.

E-mail addresses: yoann.greau@mq.edu.au, yoanngreau@aol. com (Y. Greau).

6928 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

1. INTRODUCTION

The study of ultramafic massifs worldwide, as well as thestudy of xenolith suites brought to the surface by kimber-lites and alkali basalts, has shown that the subcontinentallithospheric mantle (SCLM) is a complex mixture of maficand ultramafic lithologies. An understanding of the originof the mafic bodies and their role in mantle processes isrequired to understand the larger picture of mantle dynam-ics. As a part of these processes, the nature and origins ofmantle-derived eclogites need to be constrained. Unfortu-nately, no consensus has yet been reached and hypotheseson their origins involve very different processes (e.g. sub-duction, partial melting, underplating). This difficulty inreaching a clear consensus reflects the fact that mantle-derived eclogites have resided in the SCLM, which has beenintensively modified through time by metasomatic refertili-sation processes (e.g. Griffin et al., 2003; Kobussen et al.,2009), implying that these eclogites also have experiencedsuch metasomatic events (e.g. Sobolev et al., 1999b; Jacobet al., 2009; Smart et al., 2009).

Pioneering works (Macgregor and Carter, 1970; Hattonand Gurney, 1977; Hatton, 1978) based on petrographysuggested that mantle-derived eclogites are the crystallisa-tion products of deep-seated mafic melts. However, Helms-taedt and Doig (1975) pointed out the similarities betweenlawsonite-bearing eclogites from kimberlites on the Colo-rado Plateau and eclogites from exhumed subduction belts,and suggested that kimberlite-borne eclogite xenoliths ulti-mately were of subduction-related origin. Several studiesthen carried that idea into studies of cratonic eclogite xeno-liths (Helmstaedt and Schulze, 1979; Ater et al., 1984;Jagoutz et al., 1984) and interpretations of oxygen-isotopedata (Macgregor and Manton, 1986) strengthened theapparent link between mantle-derived eclogites and sub-ducted oceanic crust.

The existence of several types of eclogites was recognisedquite early (e.g. Coleman et al., 1965) and classificationschemes were developed (e.g. Coleman et al., 1965;Macgregor and Carter, 1970; Hatton, 1978; Dawson,1980; Mccandless and Gurney, 1989; Taylor and Neal,1989). The most enduring classification for kimberlite-borne eclogites, proposed by MacGregor and Carter(1970), is based on the microstructural differences betweenthe two main types (designated Type I and Type II) that oc-cur in the kimberlites of the Roberts Victor mine (SouthAfrica). This pipe is unusual in that the xenolith populationconsist of >90% eclogites. Type I eclogites were mainly de-scribed as having coarse-grained subhedral to rounded“dusty” garnets within a matrix of anhedral to interstitialclinopyroxene, commonly with a patchy distribution of gar-nets and sometimes layering. Eclogites displaying a roughplanar fabric, defined by the arrangement of elongated,clear, unaltered garnets and anhedral clinopyroxenes, andshowing oriented exsolution of rutile in both garnet andclinopyroxene were assigned to Type II.

Several attempts at chemical classification have beenmade (Mccandless and Gurney, 1989; Taylor and Neal,1989) but perhaps the most important contribution hasbeen that of McCandless and Gurney (1989), who showed

that the microstructural groups defined by MacGregorand Carter (1970) have different Na2O contents in garnetsand K2O contents in clinopyroxenes. Samples in which gar-nets have 60.9 wt% Na2O and clinopyroxenes haveK2O 6 0.8 wt% belong to Type II; all others belong to TypeI. This classification was later refined and a limit of60.7 wt% Na2O in garnets was adopted for Type II eclog-ites (Schulze et al., 2000). The sampling done for this studyand the more systematic sampling of Hatton (1978; 750samples classified) indicate that only 6–8% of the RobertsVictor xenoliths are Type II eclogites.

The distinction between Type I and Type II eclogites,originally developed at Roberts Victor, can be recognisedin the few Kaapvaal kimberlites in which eclogites are abun-dant enough to have been studied in detail, including Bells-bank and Bobbejahn (Smyth et al., 1989) and Kaalvallei(Viljoen et al., 2005). However, in most kimberlites of thiscraton, as in other cratons worldwide, eclogites make up0–15% of the total xenolith population, and typically aresmall in size (Schulze, 1989). The statistics of samplingtherefore mitigate against the recognition of Type II eclog-ites in these pipes, even where eclogite xenoliths have beenfound.

The present study investigates in detail the petrologicaland geochemical characteristics of Type I and Type IIeclogites from Roberts Victor. The results highlight somecrucial differences between the two types that imply con-trasting histories and supply some key information aboutprocesses affecting the SCLM.

2. GEOLOGICAL SETTING AND SAMPLES

The Roberts Victor mine (Lat: 28� 270S Long: 25� 340E;South Africa) is located in the Orange Free State, approxi-mately 100 km NE of Kimberley. South African kimberlitescan be divided on isotopic and petrographic criteria (Smith,1983) into an older Group II (>110 Ma) and a youngerGroup I (mostly <95 Ma). The Roberts Victor kimberlitesbelong to Group II and Rb/Sr dating on phlogopite givesan age of 128 ± 15 Ma (Smith et al., 1985). The kimberliteis diamondiferous and eclogite xenoliths make up 95–98%of the abundant xenolith population (Macgregor andCarter, 1970; Hatton, 1978); individual xenoliths can be>50 cm in diameter. The few ultramafic xenoliths presentare harzburgites, garnet harzburgites and garnet lherzolites,usually intensively altered to serpentine, calcite and quartz(Williams, 1932; Hatton, 1978; Viljoen et al., 1991).

A “chemical tomography” section of the peridotiticmantle, constructed from garnet xenocrysts, shows a highlydepleted lithospheric mantle with a distinct base at180 ± 10 km depth, underlain by a 10 to 20-km thick layerin which the eclogites are strongly concentrated (Griffin andO’reilly, 2007).

The sample suite used in this study is made up of 29xenoliths (selected from a collection of >200 samples). Mostof the samples (RV07-“XX”) were collected in 2006 fromthe Roberts Victor dumps (26 samples). The other sampleswere already in the GEMOC collection (RV73-12) or havebeen graciously lent by Prof. John Gurney (XRV6;HRV77). The samples studied in this work include 20 Type

Fig. 1. Petrographic features of Roberts Victor eclogites. (A) Type II eclogites. (1) Thin section of sample RV07-12 illustrating the ovoidshapes of garnet and their preferential orientation. (2) Microphotograph of cpx exhibiting multi-orientated rutile exsolution. (3)Microphotograph of garnet with exsolved rutile needles, note the translucent aspect (“clear”) of the garnet. (4) BSE image of a cpx macrocrystshowing multiple generations of garnet exsolution. (5) Microphotograph of a garnet-silica symplectite occurring at some garnet-cpxboundaries. (B) Type I eclogites. (1) Thin section of RV07-11 illustrating the ”chaotic” microstructure, with irregular grain boundaries and theclustering of “dusty” garnets. (2) Detail of XRV6 thin section showing intensive contrast in the “dusty” aspect of garnet linked to thedistribution of fluid inclusions. (3) BSE image of “melt-pockets” in garnet containing secondary minerals (phlogopite, spinel, feldspar,zeolites) and glass. (4) BSE image of cpx displaying pervasive secondary “spongy” cpx (also observable in Type II). (5) BSE image ofindividual phlogopite inclusions, surrounded by spongy cpx.

Roberts Victor eclogites: A metasomatic history 6929

I and 9 Type II eclogites; the latter include all of the Type IIeclogites recognised in our collection.

The samples collected in 2006 are of different sizes. Sam-ples labelled from RV07-1 to RV07-29 are rounded to dis-coid xenoliths ranging from fist-sized to 24 � 22 cm.Samples labelled from RV07-30 to RV07-66 do not exceed5 cm length.

Within this suite, samples HRV77 and RV07-17 wererecognised to be of special interest. HRV77 is a unique

composite xenolith in which a clinopyroxene macrocrystis enclosed in a Type I bimineralic eclogite. Due to themicrostructural differences, each part was processed sepa-rately. The bimineralic part is labelled “HRV77bimin” andthe cpx macrocryst “HRV77macrocx” in the following textand tables. HRV77macrocx is particularly interesting as itshows features transitional between Type I and Type IIeclogites (see details in Section 4, Petrography and Min-eral Chemistry).

0.00

0.05

0.10

0.15

0.20

0.00 0.05 0.10 0.15 0.20

Type IType II

Type II

Type I

Na2O Garnet (wt%)

K2O

Cpx

(wt%

)

0.08

0.07

HRV77macrocx

0.25

0.30

0.35

Fig. 2. Na2O in garnet vs. K2O in cpx. Dashed lines separate thecompositional fields of Type I and Type II eclogites as defined byMcCandless and Gurney (1989). All samples of this suite follow theclassification with the exception of HRV77macrocx. For comparison,Roberts Victor eclogites from the literature have been plotted(Jacob et al., 2005; MacGregor and Manton, 1986), grey diamonds:Type I; black dots: Type II.

6930 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

RV07-17 is a Type I eclogite in terms of the Na contentof garnet, but shows microstructural features as well as ma-jor-element variations across the sample more reminiscentof Type II eclogites.

3. METHODS

Major-element contents of silicates and sulphides wereanalysed using a CAMECA SX100 electron microprobeat GEMOC fitted with five crystal spectrometers. Analyseswere done with an accelerating voltage of 15 kV and a20 nA beam current. Counting times were 10 s for peaksand 5 s for backgrounds on either side of the peak, and cor-rections were done by the method of Pouchou and Pichoir(1984).

Trace-element concentrations of garnet and clinopyrox-ene have been measured in situ using the LAM-ICPMSfacilities at GEMOC. Analyses were carried out in a pureHe atmosphere with a New Wave UP213nm Nd:YAG lasermicroprobe coupled to an Agilent 7500cs ICPMS. Operat-ing conditions included a 60 lm beam diameter with a pulsefrequency of 5 Hz and laser intensity around 0.150 mJ. Cal-cium was used as the internal standard and the NIST 610glass as the external standard. The ablation sequence lasted260 s with a background segment of 120 s, and a wash-outtime of 5 min was observed between analyses. The raw datawere processed on-line using the software package GLIT-TER� (Griffin et al., 2008; www.gemoc.mq.edu.au). Inter-national standard BCR-2G and an in-house garnetstandard (MONGOL) were analysed before and after eachrun as a cross-check on accuracy (Electronic appendix 1).

Major- and trace-element compositions of whole-rocksamples were analysed by Geosciences Australia (Can-berra). Major-element concentrations were obtained byXRF analysis of fused discs using a Philips PW 2404 XRFspectrometer. A large suite of trace-element concentrationswas determined by ICP-MS analysis (Agilent 7500 ICP-MS) of the digested fused discs used for the major elementXRF analysis. Two international standards, a basalt(B.R.) and a kimberlite (SARM39-South African Bureauof Standards) were also fused and analysed by XRF beforethe discs were digested and run through the ICP-MS. All theelement abundances obtained for these standards were ingood agreement with their recommended values.

Oxygen isotopes have been determined on mineral sepa-rates at the Laboratoire des Transferts Lithospheriques(Universite Jean Monnet, Saint-Etienne, France). Opticallyclear grains of garnet and clinopyroxene were handpickedusing a binocular microscope and then processed for oxy-gen extraction using a BrF5 and CO2 laser-heating setup(Sharp, 1990). Extraction was done on one or several grainsdepending on their weight (wtotal = 2–3 mg). Extraction effi-ciency and reproducibility were compared to the MonasteryGarnet standard and pure SiO2 glass. Uncertainties are be-tween ±0.2& and ±0.3&. The isotopic composition of theextracted oxygen was analysed using a Micromass ISO-PRIME dual-inlet stable Isotope-Ratio Mass-Spectrometer(IR-MS). The results were normalised to the values ob-tained for the international standard V-SMOW (ViennaStandard Mean Ocean Water; Coplen, 1988).

4. PETROGRAPHY

Petrography was an important component of the earlystudies and a key element in the original suggestions of amagmatic origin (Macgregor and Carter, 1970; Harte andGurney, 1975; Lappin and Dawson, 1975; Hatton andGurney, 1977; Smyth et al., 1989; Sautter and Harte,1990). However, with the development of geochemical tech-niques, more attention has been focused on the chemicalaspects of these rocks and less on petrographic observa-tions. For this reason, we have taken care to combinedetailed petrography and chemistry in order to not omitinformation related to mineral parageneses or microstruc-tural relationships.

4.1. Type II eclogites

As defined by MacGregor and Carter (1970), Type IIeclogites commonly have a roughly planar fabric definedby the parallel arrangement of irregular to elongated gar-nets within a matrix of coarse interlocking clinopyroxenes(Fig. 1A-1).

Garnet and clinopyroxene are the main constituents,with only minor fine-grained secondary phlogopite, spinel,amphibole, zeolites and feldspars along the grain bound-aries. Both garnet and clinopyroxene are fresh and do notcontain fluid inclusions (Fig. 1A-2 and A-3). However, asin most eclogite xenoliths, omphacitic clinopyroxene tendsto be secondarily destabilised into a spongy clinopyroxene(Fig. 1A-5 and B-4), believed to form during ascent in thehost kimberlite (e.g. Donaldson, 1978; Pearson et al., 1995).

A characteristic feature of Type II eclogites is the pres-ence of multi-oriented rutile needles or blocky prisms,apparently exsolved from both garnet and clinopyroxene(Fig. 1A-2 and A-3). The exsolved rutile needles are

Table 1Major-element compositions of garnets in wt%.

Sample RV07-1 RV07-2 RV07-3 RV07-7 RV07-11 RV07-13 RV07-14 RV07-16 RV07-18 RV07-19 RV07-20 RV07-22 RV07-24 RV07-29a RV07-29b RV07-40 RV07-41 RV07-17

Average Min–max

Classification

McCandless and Gurney (1989) I I I I I I I I I I I I I I I I I I I

Microstructural/trace elements I I I I I I I I I I I I I I I I I I I

n analyses 13 23 19 13 11 16 14 18 21 22 22 9 12 7 5 10 7 21

SiO2 41.86 ± 0.22 41.25 ± 0.20 40.71 ± 0.18 41.42 ± 0.21 41.63 ± 0.10 40.84 ± 0.27 41.54 ± 0.16 41.58 ± 0.21 41.44 ± 0.16 41.50 ± 0.21 41.07 ± 0.21 41.90 ± 0.19 41.52 ± 0.14 41.73 ± 0.11 41.68 ± 0.12 41.99 ± 0.55 41.15 ± 0.36 40.92 40.6–41.3

TiO2 0.32 ± 0.02 0.35 ± 0.04 0.55 ± 0.02 0.26 ± 0.03 0.29 ± 0.05 0.34 ± 0.03 0.29 ± 0.02 0.29 ± 0.02 0.27 ± 0.02 0.28 ± 0.04 0.36 ± 0.03 0.27 ± 0.03 0.29 ± 0.03 0.31 ± 0.02 0.30 ± 0.01 0.41 ± 0.04 0.28 ± 0.03 0.33 0.3–0.4

Al2O3 22.92 ± 0.14 22.72 ± 0.12 21.79 ± 0.11 23.17 ± 0.13 22.98 ± 0.14 22.60 ± 0.09 23.14 ± 0.09 23.33 ± 0.10 22.88 ± 0.08 22.99 ± 0.17 22.25 ± 0.09 22.97 ± 0.11 23.00 ± 0.15 22.89 ± 0.07 23.10 ± 0.04 23.28 ± 0.21 23.09 ± 0.09 22.38 22.1–22.6

Cr2O3 0.16 ± 0.02 0.15 ± 0.00 0.09 ± 0.02 0.09 ± 0.02 0.10 ± 0.02 0.12 ± 0.02 0.15 ± 0.02 0.08 ± 0.03 0.10 ± 0.02 0.08 ± 0.02 0.06 ± 0.02 0.09 ± 0.02 0.09 ± 0.02 0.14 ± 0.03 0.17 ± 0.01 0.09 ± 0.06 0.20 ± 0.02 0.17 0.1–0.2

FeOtotal 15.54 ± 0.16 17.30 ± 0.28 18.52 ± 0.16 15.69 ± 0.11 15.58 ± 0.21 19.00 ± 0.43 15.24 ± 0.11 13.46 ± 0.16 15.19 ± 0.14 14.30 ± 0.12 17.25 ± 0.17 15.00 ± 0.10 13.28 ± 1.34 14.59 ± 0.10 14.70 ± 0.18 11.87 ± 0.019 17.11 ± 0.26 17.70 16.8–18.2

MnO 0.47 ± 0.03 0.45 ± 0.03 0.46 ± 0.03 0.47 ± 0.03 0.46 ± 0.03 0.96 ± 0.11 0.48 ± 0.03 0.25 ± 0.02 0.41 ± 0.03 0.42 ± 0.02 0.70 ± 0.04 0.40 ± 0.02 0.32 ± 0.11 0.43 ± 0.03 0.45 ± 0.05 0.28 ± 0.05 0.40 ± 0.02 0.45 0.4–0.5

MgO 16.04 ± 0.12 14.90 ± 0.19 13.70 ± 0.11 15.53 ± 0.11 15.73 ± 0.09 13.60 ± 0.72 15.83 ± 0.10 14.01 ± 0.14 16.05 ± 0.14 14.81 ± 0.18 14.93 ± 0.14 16.17 ± 0.10 14.52 ± 0.55 15.60 ± 0.13 15.49 ± 0.18 18.56 ± 0.26 16.31 ± 0.19 13.89 13.1–15.3

CaO 4.72 ± 0.16 4.25 ± 0.09 5.20 ± 0.08 4.68 ± 0.11 4.53 ± 0.11 4.18 ± 0.34 4.81 ± 0.06 8.60 ± 0.28 4.81 ± 0.18 6.73 ± 0.21 4.46 ± 0.08 4.52 ± 0.05 8.31 ± 1.86 5.55 ± 0.21 5.66 ± 0.29 4.74 ± 0.26 3.04 ± 0.03 5.30 4.5–6.0

Na2O 0.11 ± 0.00 0.11 ± 0.01 0.14 ± 0.00 0.11 ± 0.01 0.10 ± 0.01 0.12 ± 0.01 0.11 ± 0.01 0.12 ± 0.01 0.11 ± 0.01 0.13 ± 0.05 0.07 ± 0.01 0.11 ± 0.01 0.11 ± 0.01 0.11 ± 0.01 0.11 ± 0.01 0.11 ± 0.02 0.09 ± 0.01 0.11 0.10–0.15

K2O <0.02 ± 0.02 <0.02 ± 0.01 <0.02 ± 0.00 <0.02 ± 0.00 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.00 <0.02 ± 0.02 <0.02 ± 0.00 0.03 ± 0.13 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.00 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 0–0.2

NiO 0.01 ± 0.01 0.01 ± 0.00 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02 0.02 ± 0.02 0.01 ± 0.02 <0.01 ± 0.01 0.02 ± 0.02 0.01 ± 0.02 0.01 0–0.04

Total 102.16 101.49 101.17 101.44 101.40 101.77 101.61 101.74 101.28 101.28 101.18 101.45 101.46 101.36 101.68 101.35 101.68 101.28

Mg# 0.65 0.61 0.58 0.64 0.64 0.57 0.65 0.65 0.66 0.65 0.62 0.66 0.66 0.66 0.65 0.75 0.65 0.59

End-members

Pyrope 56.79 53.51 49.84 55.68 56.18 49.36 56.50 50.21 57.48 53.03 53.96 57.60 51.91 55.68 55.17 65.53 58.70 50.28

Almandine 30.22 34.63 35.93 31.36 31.22 37.82 30.16 27.06 29.36 28.73 33.21 29.99 26.18 29.22 29.38 22.09 32.48 34.99

Grossular 10.17 9.72 9.81 11.18 10.96 8.80 11.00 21.54 9.98 16.73 8.27 10.94 20.03 13.41 13.62 9.10 3.80 11.40

Spessartine 0.95 0.92 0.96 0.97 0.94 1.98 0.97 0.52 0.84 0.85 1.44 0.81 0.65 0.86 0.90 0.57 0.82 0.93

Andradite 1.01 0.29 2.28 0.17 0.00 1.20 0.56 0.00 1.66 0.00 2.34 0.00 0.54 0.00 0.08 1.82 3.31 1.47

Uvarovite 0.30 0.29 0.17 0.16 0.19 0.23 0.29 0.15 0.19 0.15 0.12 0.17 0.17 0.26 0.32 0.16 0.39 0.32

Sample HRV77bimin XRV6 XRV6 RV07-9a RV07-9b RV73-12 RV07-8 RV07-12 RV07-30 RV07-31 RV07-33 RV07-34 RV07-36 RV07-37 RV07-66 HRV77macrocx

Dusty garnet Clean garnet Phlogopite-bearing

Classification

McCandless and

Gurney (1989)

I I I I I II II II II II II II II II II I

Microstructural/

trace elements

I I I I I II II II II II II II II II II II

n analyses 19 55 13 15 13 6 21 22 15 27 24 27 11 9 95 44

SiO2 41.24 ± 0.66 40.01 ± 0.53 39.83 ± 0.19 41.17 ± 0.20 40.85 ± 0.11 40.80 ± 0.24 40.08 ± 0.13 40.29 ± 0.18 39.86 ± 0.18 39.78 ± 0.17 39.32 ± 0.17 39.87 ± 0.21 40.77 ± 0.23 40.37 ± 0.25 40.60 ± 0.04 40.64 ± 0.69

TiO2 0.26 ± 0.03 0.38 ± 0.03 0.32 ± 0.04 0.32 ± 0.04 0.31 ± 0.03 0.13 ± 0.02 0.16 ± 0.03 0.15 ± 0.05 0.10 ± 0.02 0.14 ± 0.03 0.15 ± 0.02 0.18 ± 0.02 0.12 ± 0.03 0.11 ± 0.01 0.08 ± 0.01 0.29 ± 0.01

Al2O3 22.36 ± 0.47 22.35 ± 0.19 22.43 ± 0.11 22.40 ± 0.13 22.43 ± 0.09 22.29 ± 0.19 22.03 ± 0.08 21.89 ± 0.39 22.41 ± 0.09 22.32 ± 0.09 21.97 ± 0.11 22.05 ± 0.06 22.45 ± 0.13 22.65 ± 0.06 22.80 ± 0.55 22.49 ± 0.15

Cr2O3 0.19 ± 0.03 0.08 ± 0.02 0.08 ± 0.02 0.32 ± 0.07 0.13 ± 0.01 0.24 ± 0.04 0.03 ± 0.02 0.14 ± 0.03 0.08 ± 0.01 0.05 ± 0.02 0.04 ± 0.01 0.04 ± 0.02 0.14 ± 0.04 0.08 ± 0.03 0.15 ± 0.02 0.22 ± 0.03

FeOtotal 17.35 ± 0.41 17.71 ± 0.18 17.57 ± 0.00 17.44 ± 0.43 19.32 ± 0.36 20.67 ± 0.21 19.20 ± 0.18 21.14 ± 0.45 18.20 ± 0.28 17.93 ± 0.30 18.58 ± 0.10 17.58 ± 0.16 19.46 ± 0.15 18.81 ± 0.13 17.59 ± 0.42 16.88 ± 0.23

MnO 0.46 ± 0.04 0.53 ± 0.03 0.49 ± 0.02 0.99 ± 0.05 1.09 ± 0.05 0.42 ± 0.02 0.46 ± 0.02 0.44 ± 0.03 0.35 ± 0.03 0.36 ± 0.03 0.35 ± 0.02 0.42 ± 0.03 0.34 ± 0.04 0.36 ± 0.02 0.42 ± 0.03 0.37 ± 0.02

MgO 14.76 ± 0.41 13.24 ± 0.47 11.27 ± 0.18 15.05 ± 0.27 13.84 ± 0.24 13.35 ± 0.16 8.05 ± 0.17 10.60 ± 0.31 11.53 ± 0.09 10.16 ± 0.19 9.25 ± 0.10 7.38 ± 0.29 14.09 ± 0.25 11.85 ± 0.11 14.81 ± 0.17 12.68 ± 0.33

CaO 4.63 ± 0.19 5.99 ± 0.49 8.50 ± 0.17 3.59 ± 0.19 3.48 ± 0.11 3.37 ± 0.03 11.28 ± 0.28 6.80 ± 0.33 7.58 ± 0.22 9.51 ± 0.23 10.35 ± 0.13 13.58 ± 0.45 4.21 ± 0.25 7.11 ± 0.19 4.26 ± 0.40 7.44 ± 0.15

Na2O 0.11 ± 0.04 0.13 ± 0.02 0.11 ± 0.01 0.10 ± 0.01 0.10 ± 0.02 0.05 ± 0.00 0.05 ± 0.01 0.04 ± 0.01 0.04 ± 0.01 0.05 ± 0.01 0.05 ± 0.02 0.05 ± 0.01 0.03 ± 0.01 0.04 ± 0.01 0.03 ± 0.08 0.14 ± 0.10

K2O <0.02 ± 0.01 0.02 ± 0.05 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.00 0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.00 <0.02 ± 0.00 <0.02 ± 0.00 <0.02 ± 0.00 <0.02 ± 0.01 <0.02 ± 0.04 <0.02 ± 0.01

NiO 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02 0.01 ± 0.01 0.02 ± 0.02 0.01 ± 0.01 0.02 ± 0.02 0.01 ± 0.01

Total 101.40 100.44 100.62 101.38 101.57 101.35 101.35 101.52 100.17 100.30 100.08 101.16 101.63 101.40 100.77 101.16

Mg# 0.61 0.59 0.55 0.61 0.57 0.54 0.43 0.48 0.55 0.52 0.49 0.44 0.59 0.54 0.62 0.58

End-members

Pyrope 53.04 49.07 42.00 54.02 50.23 48.49 29.89 39.04 43.04 38.00 35.01 27.52 51.34 43.65 54.19 46.18

Almandine 33.94 34.07 34.35 34.38 38.47 41.49 39.13 41.90 35.82 35.69 36.16 35.27 36.77 36.72 33.52 33.40

Grossular 9.51 11.07 18.53 6.85 6.96 7.00 28.51 14.70 16.55 22.36 22.92 33.75 5.95 15.23 6.77 16.80

Spessartine 0.94 1.11 1.03 2.01 2.26 0.86 0.96 0.92 0.74 0.77 0.76 0.90 0.70 0.75 0.88 0.77

Andradite 1.75 3.81 3.34 1.57 1.27 1.45 1.15 2.88 3.50 2.83 4.80 2.15 4.75 3.29 4.20 1.90

Uvarovite 0.36 0.16 0.15 0.61 0.25 0.46 0.06 0.28 0.16 0.10 0.07 0.07 0.26 0.16 0.28 0.43

n = number of analysis.Mg# = Mg/(Mg + Fe).

Ro

berts

Victo

reclo

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metaso

matic

histo

ry6931

20406080

Ca

Mg Fe

a

20

40

60 40

60

80

b

HRV77biminHRV77macrocx

RV07-17

HRV77bimin

HRV77macrocx

RV07-17

Cr 2O

3 gar

net (

wt%

)

Mg# garnet

Type IType II

Type IType II

0.0

0.1

0.2

0.3

0.4

0.3 0.4 0.5 0.6 0.7 0.8

Fig. 3. Major-element composition of garnets. (a) Ca–Fe–Mg(mol%) diagram. (b) Cr2O3 vs. Mg-number (Mg#). Symbol same asFig. 2.

6932 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

oriented in specific directions and cross each other at spe-cific angles. These needles show an anomalous oblique (ca32�) extinction, indicating that they are elongated parallelto a pyramid face rather than the usual (001) prism. Griffinet al. (1971) originally described this feature in eclogitesfrom kimberlites and from the UHP terrain in the WesternGneiss Region of Norway. Similar inclusions also havebeen observed in majoritic garnets from various locations(Van Roermund et al., 2000; Song et al., 2004) and thisunusual crystallography was interpreted as reflecting exso-lution on cooling at high pressure (>6 GPa; Hwang et al.,2000; Griffin, 2008).

Exsolution of garnet from clinopyroxene is also a fea-ture we have observed only in Type II eclogites. The ex-solved garnet can be found as parallel lamellae in smallclinopyroxene grains where garnet is already modally abun-dant in the rock. It can also form well-defined lamellae inmacrocrystic clinopyroxenes (Fig. 1A-4). We have recogni-sed at least 4 different orientations; similar exsolution fea-tures have been described by Sautter and Harte (1988;Sautter and Harte, 1990) who also attributed them to cool-ing from high temperature (ca 1300 �C).

Some Type II samples show very localised silica/garnetsymplectites on the edges of some garnet grains (Fig. 1A-5). The nature of the silica (quartz or coesite) is unknowndue to the small size of some of our samples (allowing onlyone thick section) or due to preferential alteration of thesesymplectites (e.g. RV07-8).

4.2. Type I eclogites

Type I eclogites are characterised by coarse-grained,subhedral to rounded garnets and anhedral clinopyroxenes.Garnet often displays a patchy distribution or more com-monly a clustering of grains (Fig. 1B-1). At the xenolithscale, some samples show a well-defined layering markedby large variations in the garnet/clinopyroxene ratio fromlayer to layer.

Garnet and clinopyroxene are the main primary constit-uents of the eclogites. However, several accessory mineralscan be considered as part of the primary assemblage ofType I eclogites: phlogopite (Fig. 1B-5), sulphide and rutile.The term “primary” is used here to distinguish these fromsimilar phases that may be present but appear to have akimberlite-related origin. Except for rutile, these mineralsare not found in the primary assemblage of Type II eclog-ites. While rutile is found as needles within the silicates ofType II, it occurs as relatively coarse grains (commonlysubhedral) in Type I. It is mostly in interstitial positionsbut can also be found enclosed in both garnet and clinopy-roxene. Where phlogopite is primary (e.g. RV07-9, RV07-3), it occurs as wide patches (up to 2 cm across) and/or asinclusions in clinopyroxene. Nevertheless, even in samplesbearing primary phlogopite, secondary (kimberlite-related)phlogopite is also found but its structural position betweengrains and its major-element compositions are distinctivefrom those the primary phlogopite. Ni–Cu–Fe sulphides oc-cur as both interstitial and enclosed phases. However, theenclosed sulphides only occur in the outer rims of garnetand/or clinopyroxene grains. As in Type II eclogites,

secondary phlogopite, spinel, amphibole, zeolites and feld-spars are found along grain boundaries.

Whereas garnets in Type II eclogites are clear, garnets inType I display a dusty aspect due to the presence of abun-dant, very small (<1 lm) and uncharacterised fluid inclu-sions. In Type I eclogites, garnets display highlycurvilinear rims with many indentations, while garnets inType II are more equilibrated with smooth rims. SeveralType I samples have poikilitic microstructures with garnetenclosing clinopyroxene and clinopyroxene enclosing gar-net, suggesting strong, but incomplete, recrystallisation inthose samples (e.g. RV07-11, RV07-16).

Another petrographic difference between Type I andType II garnets is the common presence in Type I of globu-lar structures similar to melt pockets (Fig. 1B-3), which areabsent in Type II garnets. Those pockets contain the samemineral assemblage as is found along grain boundaries(e.g. phlogopite, amphibole, analcime, spinel, feldspar).

5. MINERAL CHEMISTRY

5.1. Major elements

Major-element compositions of the main silicate assem-blage are in general homogeneous and do not show zoningin minerals nor chemical variations across single samples.However, a few samples (e.g. HRV77, RV07-17, XRV6)present some variations and are treated separately below.

5.1.1. Garnets

Garnets from eclogitic parageneses are solid solutionsbetween three principal end-members: pyrope(Mg3Al2-(SiO4)3), grossular (Ca3Al2(SiO4)3) and almandine(Fe3Al2(SiO4)3).

Table 2Major-element compositions of clinopyroxenes in wt%.

Sample RV07-1 RV07-2 RV07-3 RV07-7 RV07-11 RV07-13 RV07-14 RV07-16 RV07-17 RV07-18 RV07-19 RV07-20 RV07-22 RV07-24 RV07-29a RV07-29b RV07-40

Classification

McCandless and

Gurney (1989)

I I I I I I I I I I I I I I I I I

Microstructural/

trace elements

I I I I I I I I I I I I I I I I I

n analyses 14 26 21 8 17 18 13 12 17 17 16 25 9 10 6 8 5

SiO2 56.64 ± 0.21 55.66 ± 0.19 54.96 ± 0.35 56.18 ± 0.20 56.02 ± 0.21 55.68 ± 0.28 56.19 ± 0.13 56.94 ± 0.18 55.71 ± 0.17 56.14 ± 0.24 56.91 ± 0.14 54.92 ± 0.18 56.44 ± 0.41 56.35 ± 0.26 56.12 ± 0.28 56.14 ± 0.14 55.72 ± 0.46

TiO2 0.38 ± 0.02 0.41 ± 0.02 0.50 ± 0.03 0.36 ± 0.01 0.34 ± 0.02 0.39 ± 0.01 0.38 ± 0.01 0.36 ± 0.02 0.43 ± 0.02 0.38 ± 0.02 0.39 ± 0.01 0.16 ± 0.02 0.38 ± 0.02 0.37 ± 0.02 0.36 ± 0.01 0.37 ± 0.01 0.42 ± 0.02

Al2O3 8.38 ± 0.17 6.91 ± 0.10 6.00 ± 0.14 8.46 ± 0.11 7.76 ± 0.16 6.73 ± 0.09 8.85 ± 0.09 13.80 ± 0.21 8.02 ± 0.50 9.25 ± 0.28 12.40 ± 0.26 3.08 ± 0.05 8.96 ± 0.33 12.01 ± 1.64 8.14 ± 0.16 8.39 ± 0.42 5.10 ± 0.08

Cr2O3 0.19 ± 0.02 0.14 ± 0.02 0.07 ± 0.02 0.11 ± 0.02 0.10 ± 0.02 0.16 ± 0.02 0.17 ± 0.02 0.10 ± 0.02 0.19 ± 0.03 0.12 ± 0.02 0.11 ± 0.02 0.03 ± 0.02 0.11 ± 0.02 0.11 ± 0.01 0.13 ± 0.02 0.17 ± 0.02 0.04 ± 0.02

FeOtotal 4.60 ± 0.10 6.06 ± 0.11 7.24 ± 0.13 4.90 ± 0.07 4.93 ± 0.07 7.25 ± 0.18 4.48 ± 0.07 2.54 ± 0.07 5.57 ± 0.18 4.36 ± 0.15 3.16 ± 0.06 7.21 ± 0.08 4.48 ± 0.23 3.07 ± 0.66 4.29 ± 0.14 4.23 ± 0.10 3.80 ± 0.05

MnO 0.09 ± 0.02 0.11 ± 0.02 0.10 ± 0.02 0.10 ± 0.02 0.10 ± 0.02 0.25 ± 0.01 0.09 ± 0.02 0.03 ± 0.02 0.08 ± 0.02 0.09 ± 0.02 0.05 ± 0.01 0.20 ± 0.03 0.09 ± 0.02 0.05 ± 0.02 0.09 ± 0.01 0.07 ± 0.02 0.07 ± 0.02

MgO 11.57 ± 0.11 12.16 ± 0.13 11.79 ± 0.12 11.67 ± 0.12 12.04 ± 0.11 12.40 ± 0.13 11.36 ± 0.10 8.34 ± 0.18 11.10 ± 0.49 11.07 ± 0.36 9.05 ± 0.17 14.85 ± 0.10 11.42 ± 0.38 9.31 ± 0.99 11.66 ± 0.24 11.56 ± 0.29 14.48 ± 0.14

CaO 14.11 ± 0.08 14.36 ± 0.11 14.84 ± 0.15 13.98 ± 0.08 14.39 ± 0.16 13.37 ± 0.15 13.88 ± 0.11 11.98 ± 0.14 14.04 ± 0.15 13.45 ± 0.35 12.15 ± 0.24 17.40 ± 0.13 13.56 ± 0.14 12.77 ± 0.74 14.74 ± 0.19 14.84 ± 0.33 17.51 ± 0.20

Na2O 5.25 ± 0.11 4.76 ± 0.07 4.42 ± 0.30 5.34 ± 0.14 4.75 ± 0.08 4.68 ± 0.09 5.53 ± 0.23 7.03 ± 0.07 5.12 ± 0.19 5.42 ± 0.26 6.70 ± 0.12 2.50 ± 0.04 5.39 ± 0.23 6.39 ± 0.59 4.91 ± 0.09 5.15 ± 0.20 3.32 ± 0.06

K2O 0.14 ± 0.01 0.13 ± 0.01 0.11 ± 0.02 0.13 ± 0.01 0.14 ± 0.01 0.13 ± 0.03 0.14 ± 0.01 0.11 ± 0.01 0.16 ± 0.02 0.12 ± 0.03 0.10 ± 0.01 0.11 ± 0.01 0.13 ± 0.03 0.10 ± 0.02 0.16 ± 0.01 0.16 ± 0.01 0.08 ± 0.01

NiO 0.05 ± 0.02 0.04 ± 0.02 0.03 ± 0.02 0.03 ± 0.01 0.03 ± 0.02 0.04 ± 0.02 0.04 ± 0.02 0.05 ± 0.02 0.05 ± 0.02 0.03 ± 0.05 0.04 ± 0.02 0.02 ± 0.02 0.04 ± 0.03 0.06 ± 0.02 0.06 ± 0.02 0.02 ± 0.02 0.04 ± 0.02

Total 101.38 100.72 100.06 101.26 100.61 101.09 101.11 101.27 100.46 100.44 101.05 100.47 101.01 100.58 100.65 101.12 100.58

Mg# 0.82 0.78 0.74 0.81 0.81 0.75 0.82 0.85 0.78 0.82 0.84 0.79 0.82 0.84 0.83 0.83 0.87

Sample RV07-41 HRV77bimin XRV6 RV07-9a RV07-9b RV73-12 RV07-8 RV07-12 RV07-30 RV07-31 RV07-33 RV07-34 RV07-36 RV07-37 RV07-66 HRV77macrocx

Phlogopite-bearing

Classification

McCandless and Gurney (1989) I I I I I II II II II II II II II II II I

Microstructural/trace-elements I I I I I II II II II II II II II II II II

n analyses 16 11 12 19 18 12 13 19 11 6 7 13 7 9 19 39

SiO2 55.49 ± 0.26 55.72 ± 0.50 54.71 ± 0.21 55.35 ± 0.23 55.31 ± 0.21 55.61 ± 0.27 55.66 ± 0.11 55.23 ± 0.19 54.45 ± 0.54 54.70 ± 0.14 54.22 ± 0.14 54.61 ± 0.30 55.27 ± 0.23 55.63 ± 0.21 54.50 ± 0.18 55.89 ± 0.41

TiO2 0.22 ± 0.02 0.35 ± 0.02 0.42 ± 0.02 0.32 ± 0.02 0.34 ± 0.02 0.16 ± 0.01 0.22 ± 0.02 0.14 ± 0.02 0.18 ± 0.03 0.19 ± 0.02 0.19 ± 0.02 0.25 ± 0.03 0.13 ± 0.02 0.19 ± 0.02 0.15 ± 0.02 0.34 ± 0.02

Al2O3 5.79 ± 0.16 7.75 ± 0.35 8.31 ± 0.45 5.12 ± 0.15 4.93 ± 0.26 5.58 ± 0.18 10.14 ± 0.20 5.11 ± 0.38 9.12 ± 0.32 9.05 ± 0.25 9.36 ± 0.41 12.29 ± 0.58 4.88 ± 0.20 9.15 ± 0.18 4.64 ± 0.44 9.78 ± 0.11

Cr2O3 0.19 ± 0.02 0.19 ± 0.02 0.15 ± 0.03 0.24 ± 0.06 0.11 ± 0.03 0.22 ± 0.03 0.03 ± 0.01 0.10 ± 0.02 0.08 ± 0.02 0.06 ± 0.02 0.04 ± 0.02 0.02 ± 0.01 0.08 ± 0.02 0.07 ± 0.02 0.14 ± 0.02 0.24 ± 0.02

FeOtotal 6.61 ± 0.16 6.10 ± 0.26 5.77 ± 0.19 7.39 ± 0.16 8.22 ± 0.20 7.16 ± 0.16 5.61 ± 0.09 6.32 ± 0.20 5.82 ± 0.16 5.34 ± 0.07 6.03 ± 0.12 5.37 ± 0.09 6.89 ± 0.19 5.58 ± 0.14 4.72 ± 0.15 4.31 ± 0.10

MnO 0.14 ± 0.02 0.11 ± 0.02 0.08 ± 0.02 0.27 ± 0.02 0.33 ± 0.02 0.07 ± 0.01 0.04 ± 0.02 0.05 ± 0.02 0.03 ± 0.01 0.02 ± 0.02 0.03 ± 0.02 0.04 ± 0.02 0.05 ± 0.02 0.04 ± 0.02 0.06 ± 0.02 0.05 ± 0.02

MgO 13.75 ± 0.16 11.45 ± 0.34 10.49 ± 0.38 13.21 ± 0.15 13.17 ± 0.24 11.83 ± 0.21 8.71 ± 0.17 12.09 ± 0.27 9.36 ± 0.17 9.65 ± 0.17 9.05 ± 0.24 7.69 ± 0.25 12.56 ± 0.22 9.69 ± 0.18 13.60 ± 0.31 9.96 ± 0.08

CaO 14.21 ± 0.34 13.63 ± 0.35 13.90 ± 0.26 14.45 ± 0.19 14.18 ± 0.24 15.33 ± 0.14 14.46 ± 0.13 18.10 ± 0.32 14.66 ± 0.23 15.46 ± 0.20 15.05 ± 0.20 14.33 ± 0.08 16.84 ± 0.27 14.67 ± 0.12 18.63 ± 0.38 14.18 ± 0.10

Na2O 3.60 ± 0.11 4.68 ± 0.17 5.18 ± 0.22 3.97 ± 0.08 3.91 ± 0.18 4.61 ± 0.12 5.82 ± 0.08 3.47 ± 0.16 5.46 ± 0.10 5.18 ± 0.08 5.38 ± 0.11 5.66 ± 0.04 3.72 ± 0.07 5.54 ± 0.06 2.95 ± 0.22 5.12 ± 0.10

K2O 0.18 ± 0.01 0.11 ± 0.01 0.13 ± 0.01 0.10 ± 0.01 0.11 ± 0.02 <0.02 ± 0.01 <0.02 ± 0.00 0.02 ± 0.02 <0.02 ± 0.00 <0.02 ± 0.01 <0.02 ± 0.00 <0.02 ± 0.00 <0.02 ± 0.01 <0.02 ± 0.01 <0.02 ± 0.01 0.14 ± 0.01

NiO 0.05 ± 0.03 0.03 ± 0.02 0.04 ± 0.02 0.02 ± 0.02 0.06 ± 0.02 0.08 ± 0.03 0.03 ± 0.02 0.09 ± 0.03 0.07 ± 0.02 0.05 ± 0.02 0.04 ± 0.02 0.03 ± 0.02 0.12 ± 0.01 0.08 ± 0.02 0.10 ± 0.03 0.06 ± 0.03

Total 100.24 100.13 99.18 100.44 100.66 100.64 100.72 100.74 99.24 99.71 99.39 100.28 100.55 100.66 99.49 100.07

Mg# 0.79 0.77 0.76 0.76 0.74 0.75 0.73 0.77 0.74 0.76 0.73 0.72 0.76 0.76 0.84 0.80

n = number of analysis.Mg# = Mg/(Mg + Fe).

Ro

berts

Victo

reclo

gites:A

metaso

matic

histo

ry6933

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.1 0.2 0.3 0.4AlIV

AlVI AlI

V

Igneous rocks

Eclogite

Tsch

=2

AlIV

Granulites & inclusions in basalts

NaAl Si 2 O6 (Jd) NaFe Si 2 O6 (Ae)

Q (Wo, En, Fs)

Quad

Omphacite aegirine-augite

jadeite aegirine

80 80

20 20

50

Mg# cpx

K2O

cpx

(wt%

)

d

m.d.l.1

2

3

4

5

6

7

8

0 5 10 15 20Al2O3 cpx (wt%)

Type IType II

Na 2

O c

px (w

t%)

c

ba

0.00

0.05

0.10

0.15

0.20

0.25

0.55 0.65 0.75 0.85 0.95

0.30

0.35

0.40

HRV77bimin

HRV77macrocxRV07-17

HRV77bimin

HRV77macrocx

RV07-17

Fig. 4. Classification of clinopyroxenes and major-element compositions. (a) AlVI versus AlIV; all the samples plot in the eclogite field definedby AlIV/AlVI > 2. Fields and ratios from Aoki and Shiba (1973). (b) Na–Ca pyroxene classification (Morimoto, 1988). (c) Na2O vs. Al2O3. (d)K2O vs. Mg#. Symbol same as Fig. 2.

6934 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

5.1.1.1. Type II. Samples from this suite show the typicalType II petrographic features described by MacGregorand Carter (1970) and also fit the chemical classificationof McCandless and Gurney (1989) as can be seen onFig. 2 (Na2O 6 0.05 wt%; Table 1). The garnets have highFeO contents, from 16.9 to 21.1 wt% (average = 18.7 wt%).Most of the observed variations in garnet composition re-flect Mg–Ca exchange. Samples with higher MgO (ca14.1 wt%) and lower CaO (ca 3.93 wt%) overlap the fieldoccupied by garnets from Type I eclogites in the Ca–Fe–Mg triangle (Fig. 3a). The maximum CaO contents in TypeII garnet are 13.6 wt% at an MgO content of 7.38 wt%.

In the Cr2O3 vs. Mg# plot (Fig. 3b) garnets from TypeII eclogites define a broad positive correlation extendingfrom the lowest Cr2O3 (0.03 wt%) and Mg# (0.43), towardvalues overlapping the field of garnets from Type Ieclogites.

5.1.1.2. Type I. According to the revised McCandless andGurney classification (Schulze et al., 2000) Type I eclogiteshave garnets with P0.07 wt% Na2O. Samples petrographi-cally described as Type I correspond to this criterion withNa2O contents ranging from 0.07 to 0.14 wt% (Fig. 2). Inthe Ca–Mg–Fe diagram (Fig. 3a) Type I eclogite garnetsplot mostly in a triangle defining compositions betweenGrossular0-20 Pyrope40-60 Almandine20-40. All Type I gar-nets have Cr2O3 contents >0.06 and <0.32 wt% (Fig. 3b)with Mg# (Mg/(Mg + Fe)) ranging from 0.55 to 0.75.

5.1.2. Clinopyroxenes

5.1.2.1. Type II. Fig. 2 shows that all the samples classifiedmicrostructurally as Type II, follow the McCandless andGurney classification (1989); cpx has K2O contents60.08 wt% (up to 0.02 wt% K2O; Table 2), with the excep-tion of HRV77macrocx (0.14 wt%).

The Tschermak-Jadeite ratios of clinopyroxenes are usedto distinguish high-pressure-equilibrated clinopyroxenes(eclogite facies) from lower-pressure ones (granulite facies;White, 1964). This is equivalent to calculating clinopyroxeneAlVI/AlIV ratios (Aoki and Shiba, 1973). AlVI/AlIV ratiosP2 characterise high-pressure equilibration and correspondtherefore to eclogitic cpx or high-pressure pyroxenitic cpx(Fig. 4a). In the Na–Ca cpx diagram (Fig. 4b), all the clino-pyroxenes of Type II plot in the omphacite field.

Mg# for cpx from Type II eclogites ranges from 0.72 to0.84. The K2O vs. Mg# diagram (Fig. 4d) clearly defines thetwo main groups of samples: Type I with relatively highK2O and intermediate Mg# in cpx, Type II with low K2Oand low Mg#.

5.1.2.2. Type I. All the samples characterised as Type Iusing the petrographic classification of MacGregor andCarter (1970) have clinopyroxene K2O contents from 0.08to 0.18 wt% (Fig. 2) and have AlVI/AlIV P 2 verifying theirhigh-pressure equilibration. The Na–Ca plot (Fig. 4b)shows that they are all omphacite, still with the exceptionof RV07-20. Plotting RV07-20 cpx in an Enstatite–Wollas-

Table 3Geothermobarometry and garnet oxygen isotope composition.

Sample Type T (�C) P (GPa) Depth (km) d18OGt (&) Calculateda d18OCc (&) Calculateda d18OH2O (&)

RV07-1 I 1121 5.9 184.6 6.69 8.18 8.74RV07-2 I 1126 5.9 185.0 4.95 6.43 6.99RV07-3 I 1233 6.2 193.6 7.29 8.52 9.13RV07-7 I 1133 5.9 185.6 4.22 5.68 6.25RV07-11 I 1118 5.9 184.3 5.56 7.05 7.61RV07-13 I 1105 5.8 183.3 6.36 7.89 8.44RV07-14 I 1130 5.9 185.3 n.a. n.c. n.c.RV07-16 I 1170 6.0 188.6 4.13 5.51 6.08RV07-17 I 1135 5.9 185.8 6.26 7.71 8.28RV07-18 I 1138 5.9 186.0 6.18 7.57 8.15RV07-19 I 1162 6.0 187.9 n.a. n.c. n.c.RV07-20 I 1122 5.9 184.7 5.39 6.88 7.44RV07-22 I 1131 5.9 185.4 5.85 7.31 7.88RV07-24 I 1239 6.2 194.2 n.a. n.c. n.c.RV07-29a I 1149 6.0 186.8 5.25 6.67 7.25RV07-29b I 1143 5.9 186.3 n.a. n.c. n.c.RV07-40 I 1118 5.9 184.4 n.a. n.c. n.c.RV07-41 I 1079 5.8 181.2 n.a. n.c. n.c.XRV6 I 1243 6.2 194.4 n.a. n.c. n.c.HRV77bimin I 1191 6.1 190.3 n.a. n.c. n.c.RV07-9a I 1164 6.0 188.1 6.51 7.89 8.48RV07-9b I 1099 5.8 182.8 n.a. n.c. n.c.

RV73-12 II 1005 5.6 175.2 3.52 5.28 5.78RV07-8 II 1187 6.1 189.9 3.91 5.24 5.84RV07-12 II 975 5.3 168.3 n.a. n.c. n.c.RV07-30 II 1277 6.3 197.2 n.a. n.c. n.c.RV07-31 II 1213 6.1 192.0 n.a. n.c. n.c.RV07-33 II 1285 6.3 197.8 n.a. n.c. n.c.RV07-34 II 1305 6.4 199.5 n.a. n.c. n.c.RV07-36 II 1066 5.7 180.2 n.a. n.c. n.c.RV07-37 II 1188 6.1 190.0 n.a. n.c. n.c.RV07-66 II 869 4.5 145.0 n.a. n.c. n.c.HRV77macrocx II 1134 5.9 185.6 n.a. n.c. n.c.

T calculated using Krogh (1988).P and depth are derived from the intersection of the T–P locus and the 35 mW/m2 geotherm (Griffin et al., 2003; Griffin and O’Reilly, 2007)d18O values normalised to V-SMOW; d18OCc = d18O of CO2-rich fluid in equilibrium with garnet; d18OH2O = d18O of H2O-rich fluid inequilibrium with garnet.n.a. = not analysed.n.c. = not calculable.

a Calculated using the method described in Zheng (1993).

Roberts Victor eclogites: A metasomatic history 6935

tonite–Ferrosilite diagram (Mg2Si2O6–Ca2Si2O6–Fe2Si2O6)reveals that it has an augite composition. However, becauseit has AlVI/AlIV > 2, it will still be considered as an eclogitic(high-pressure) cpx (Fig. 4a).

The Na2O–Al2O3 plot for cpx (Fig. 4c), shows that Type IAl2O3 contents vary between 3.05 and 13.8 wt%, while Na2Ocontents spread between 2.38 wt% (RV07-20) and 7.03 wt%.Mg# (Fig. 4d) for Type I cpx ranges from 0.74 to 0.87.

5.1.3. P–T calculations

The Fe–Mg exchange between garnet and omphacite(Krogh, 1988) has been used to estimate the equilibrationtemperature (T) of this primary assemblage and to derivethe depth of origin of the xenoliths (Table 3). The lack oforthopyroxene in the eclogites precludes the direct calcula-tion of pressure (P). However, because the Fe–Mg ther-mometer is P-dependant, T can be calculated for differentP conditions and then P can be defined by the intersection

of the T–P locus and the geotherm 35 mW/m2 derived fromgarnet lherzolite xenoliths and xenocrysts of peridotitic gar-net in Roberts Victor and other Group II kimberlites in theKaapvaal craton (e.g. Griffin et al., 2003; Griffin andO’reilly, 2007). This approach relies only on the reasonableassumption that the peridotites and eclogites have equili-brated to the same geotherm.

The temperatures obtained for Type I eclogites range be-tween 1079 and 1243 �C with a mean of 1148 ± 43 �C, andcalculated depths lie between 181 and 194 km (�6 GPa).These values are consistent with those reported by Griffinand O’Reilly (2007) and indicate that the Roberts Victoreclogites were emplaced and equilibrated close to the litho-sphere–asthenosphere boundary, taken here as the base ofthe strongly depleted lithospheric mantle (Griffin et al.,2003; Griffin and O’reilly, 2007).

The temperatures obtained for Type II eclogites rangebetween 869 and 1305 �C, corresponding to depths between

0.001

0.01

0.1

1

10

100G

arne

t/CI c

hond

rites

a Type II garnets

HRV77macrocx

0.001

0.01

0.1

1

10

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

c Type I garnets

Gar

net/C

I cho

ndrit

es

XRV6 “clean”XRV6 “dusty”HRV77bimin

HRV77macrocx

b Type II garnets

0.0001

0.001

0.01

0.1

1

10

100

Gar

net/C

I cho

ndrit

es

XRV6 “clean”XRV6 “dusty”HRV77bimin

CrNi

CuK TiRb

Cs BaLa

Ce PrNd Sm

EuSr GdDy

HoY

YbLu

ZrHf

NbTaPbTh

U0.0001

0.001

0.01

0.1

1

10

d Type I garnets

Gar

net/C

I cho

ndrit

es

Fig. 5. In situ trace-element compositions of Roberts Victor garnets normalised to chondrites. (a) REE patterns of Type II garnets; Type Igarnet compositions (grey field) from this study are shown for comparison. (b) Extended trace-element patterns of Type II garnets; Type Igarnet compositions (grey field) from this study are shown for comparison. (c) REE patterns of Type I garnets; note the LREE enrichmentassociated with the dusty nature of XRV6 garnets. (d) Extended trace-element patterns of Type I garnets; note the different enrichments(LILE, HFSE, LREE) associated with the dusty nature of XRV6 garnets. Chondrites values from Anders and Grevesse (1989).

6936 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

145 and 199 km (average 184 km). Type II eclogites thuscover a somewhat wider depth range than Type I, extendingto both slightly shallower and slightly deeper levels.

5.2. Trace elements

5.2.1. Garnet

5.2.1.1. Type II. Garnets from Type II eclogites show Rare-Earth Element (REE) patterns with flat to slightly decreas-ing heavy REE (HREE) and progressive decrease frommedium REE (MREE) toward the light REE (LREE;Fig. 5a). No Eu anomalies are observed. La, Ce and Pr con-tents are usually very low and commonly are below thedetection limit of the ICP-MS (Table 4). LREE slopes aresteep; NdN/SmN (N, Chondrite-normalised) ranges from0.01 to 0.25 and GdN/LuN from 0.12 to 0.72.

Garnets in Type II eclogites are characterised by a verystrong negative Sr anomaly relative to MREE; SrN rangesfrom 0.002 to 0.010 with the exception of garnet from themacrocrystic part of HRV77 (HRV77macro) which hasSrN = 0.094 (Fig. 5b). This corresponds to Sr contentsranging from 0.02 to 0.66 ppm and Sr = 1.12 ppm inHRV77macro.

Garnets in Type II eclogites also have low Hf and Zrcontents, with ZrN ranging from 0.05 to 2.31. HfN rangesfrom 0.08 to 1.71, producing several chondrite-normalisedZr/Hf ratios <1. Nb and Ta contents are mostly belowthe detection limits. Barium contents also are generally be-low the detection limit, except for RV73-12 which has

Ba = 0.16 ppm. However, this sample also shows an unu-sual altered aspect and an enrichment in La compared toCe. Concentrations of Ni range from 12 to 59 ppm andCu contents range from 0.15 to 5.01 ppm.

5.2.1.2. Type I. Chondrite-normalised REE patterns of gar-nets in Type I eclogites (Fig. 5c) show a progressive de-crease from the HREE toward the LREE with a generallyflatter slope from the HREE towards the MREE. NdN/SmN ranges from 0.24 to 0.53 and GdN/LuN from 0.19 to0.97. Although GdN/LuN ratios are usually <1, a few sam-ples have EuN/LuN >1 (RV07-16, 1.93, RV07-24, 1.79 andRV07-40, 1.14). La is usually subchondritic with LaN rang-ing from 0.01 to 0.23. However “dusty” garnet (rich in fluidinclusions) from sample XRV6 shows a more LREE-en-riched composition with LaN = 1.14, suggesting that thefluid inclusions are LREE-enriched. HREE and Lu showa wide spread with LuN ranging from 3.38 to 26.8 timeschondrite. As for Type II garnets no EuN anomalies areobserved.

Garnets in Type I eclogites are also characterised by astrong negative SrN anomaly (Fig. 5d), although it is lesspronounced than in Type II garnets. SrN ranges from0.04 to 0.34, with the highest value corresponding to the“dusty” garnets of XRV6. Sr concentrations range from0.25 to 2.41 ppm. Where Nb concentrations are high en-ough to be detected, NbN/TaN ratios are less than 1,spreading from 0.02 to 0.95; once again the higher valuesare found in the “dusty” garnets of XRV6.

Tab

le4

Tra

ce-e

lem

ent

com

po

siti

on

so

fga

rnet

s.

Sam

ple

RV

07-1

RV

07-2

RV

07-3

RV

07-7

RV

07-1

1R

V07

-13

RV

07-1

4R

V07

-16

RV

07-1

7R

V07

-18

RV

07-1

9R

V07

-20

RV

07-2

2R

V07

-24

RV

07-2

9aR

V07

-29b

RV

07-4

0

N8

68

94

34

84

54

34

44

43

Ele

men

t

Li

pp

m0.

938

±0.

223

1.53

±0.

100.

686

±0.

031

0.77

4±

0.12

91.

21±

0.07

1.27

±0.

091.

43±

0.14

1.83

±0.

091.

42±

0.12

1.65

±0.

071.

60±

0.11

0.69

±0.

031.

49±

0.11

1.10

±0.

051.

25±

0.15

1.07

±0.

100.

457

±0.

026

Pp

pm

151

±9

139

±11

133

±8

151

±11

184

±7

162

±13

188

±20

241

±18

171

±15

147

±6

209

±16

117

163

±8

153

±6

123

±2

135

±16

480

±18

Kp

pm

n.a

.2.

57n

.a.

n.a

.b

.d.l

.2.

80±

1.43

14.8

±13

.0n

.a.

9.17

±0.

43n

.a.

n.a

.10

.932

.9±

17.1

2.90

1.84

±0.

2626

.8b

.d.l

.

Ti

pp

m17

56±

128

1949

±59

2947

±11

113

47±

146

1471

±14

118

95±

4114

55±

2615

04±

4520

81±

1016

78±

7713

94±

6919

93±

125

1760

±12

014

83±

720

92±

186

1818

±49

2690

±58

Vp

pm

118

±7

138

±4

206

±5

82±

1510

4±

1211

1±

810

9±

450

.2±

1.1

142

±2

84.2

±3.

287

.2±

6.6

372

±26

83.7

±8.

679

.5±

0.5

130

±14

115

±6

229

±8

Cr

pp

mn

.a.

895

±64

n.a

.n

.a.

615

±80

707

±35

965

±34

n.a

.12

36±

65n

.a.

n.a

.41

5±

456

2±

4047

9±

642

1±

910

15±

2643

4±

17

Ni

pp

m56

.9±

1.3

39.4

±4.

225

.0±

2.2

46.2

±2.

531

.6±

1.4

37.7

±5.

7956

.0±

10.0

67.5

±5.

642

.7±

2.8

63.0

±2.

564

.5±

2.1

21.8

±0.

157

.9±

2.0

82.6

±0.

851

.0±

1.9

51.9

±5.

461

.0±

3.4

Cu

pp

mn

.a.

0.99

±0.

10n

.a.

n.a

.0.

850

±0.

104

0.74

3±

0.05

41.

55±

0.71

n.a

.0.

875

±0.

084

n.a

.n

.a.

0.30

01.

09±

0.12

1.15

±0.

110.

983

±0.

036

0.98

0±

0.23

00.

340

±0.

054

Rb

pp

mb

.d.l

.0.

89±

0.86

0.02

9±

0.00

30.

035

±0.

011

b.d

.l.

b.d

.l.

0.10

00.

046

±0.

009

b.d

.l.

0.07

6±

0.02

30.

035

b.d

.l.

0.21

6±

0.06

3b

.d.l

.±

b.d

.l.

0.13

30.

055

±0.

010

Sr

pp

m0.

743

±0.

044

0.57

±0.

021.

20±

0.12

0.65

4±

0.12

10.

596

±0.

025

0.61

9±

0.02

10.

793

±0.

149

1.36

±0.

210.

709

±0.

107

0.75

3±

0.08

80.

986

±0.

035

0.55

3±

0.05

40.

639

±0.

033

1.16

±0.

640.

879

±0.

012

0.90

5±

0.10

60.

703

±0.

066

Yp

pm

15.4

±0.

722

.8±

1.7

32.1

±0.

611

.9±

1.6

11.6

±0.

725

.7±

0.5

14.3

±0.

414

.4±

1.3

24.6

±1.

119

.5±

2.34

412

.1±

0.7

24.7

±1.

014

.9±

0.8

8.62

±0.

0813

.8±

0.6

14.7

±0.

930

.3±

0.8

Zr

pp

m19

.8±

2.7

19.2

±2.

755

.5±

1.7

9.89

±0.

8311

.9±

3.0

26.6

±2.

515

.0±

0.3

17.8

±1.

319

.3±

2.2

18.7

±5.

389

16.1

±0.

623

.6±

1.0

16.4

±4.

722

.7±

0.8

19.0

±0.

818

.6±

0.4

67.9

±3.

3

Nb

pp

mb

.d.l

.0.

017

±0.

003

0.04

8±

0.01

80.

030

b.d

.l.

0.02

8±

0.00

60.

028

0.05

30.

026

±0.

002

0.03

6±

0.01

20.

024

±0.

007

0.03

40.

023

±0.

003

b.d

.l.

0.02

1±

0.00

10.

031

±0.

014

0.34

3

Cs

pp

m0.

014

0.01

3b

.d.l

.0.

015

b.d

.l.

b.d

.l.

0.07

8±

0.04

4b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.0.

016

±0.

001

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Ba

pp

mb

.d.l

.b

.d.l

.0.

287

±0.

148

0.46

9±

0.37

2b

.d.l

.0.

107

±0.

010

0.43

8±

0.28

90.

198

±0.

041

0.45

80.

319

±0.

194

0.30

7±

0.13

50.

389

1.18

±0.

280.

145

b.d

.l.

1.45

0.19

0

La

pp

m0.

016

±0.

002

0.01

3±

0.00

20.

054

±0.

022

0.02

6±

0.01

1b

.d.l

.0.

016

±0.

001

0.02

9±

0.00

90.

052

±0.

044

0.02

0±

0.00

50.

033

±0.

013

0.02

6±

0.01

10.

027

0.01

3±

0.00

1b

.d.l

.0.

019

±0.

004

0.02

8±

0.01

5b

.d.l

.

Ce

pp

m0.

146

±0.

016

0.10

8±

0.01

50.

389

±0.

040

0.11

8±

0.02

90.

103

±0.

011

0.12

7±

0.02

80.

146

±0.

024

0.25

0±

0.07

00.

173

±0.

020

0.13

7±

0.02

50.

215

±0.

021

0.21

7±

0.02

30.

113

±0.

006

0.21

6±

0.00

50.

166

±0.

004

0.19

2±

0.05

10.

181

±0.

014

Pr

pp

m0.

073

±0.

010

0.05

3±

0.00

70.

147

±0.

019

0.04

4±

0.01

00.

056

±0.

004

0.05

5±

0.01

00.

057

±0.

006

0.09

7±

0.01

10.

084

±0.

018

0.05

2±

0.00

20.

087

±0.

005

0.06

9±

0.00

20.

050

±0.

001

0.10

5±

0.00

40.

078

±0.

001

0.08

0±

0.01

00.

120

±0.

012

Nd

pp

m0.

805

±0.

061

0.64

6±

0.08

91.

80±

0.13

0.62

0±

0.06

70.

559

±0.

073

0.62

1±

0.07

90.

634

±0.

037

1.13

±0.

070.

697

±0.

026

0.61

2±

0.10

40.

977

±0.

071

0.85

4±

0.07

40.

613

±0.

025

1.11

±0.

030.

851

±0.

045

0.81

5±

0.02

01.

52±

0.11

Sm

pp

m0.

672

±0.

059

0.61

2±

0.04

81.

35±

0.05

0.52

2±

0.03

80.

505

±0.

085

0.70

9±

0.09

10.

650

±0.

058

0.98

7±

0.06

10.

579

±0.

052

0.67

1±

0.02

70.

769

±0.

034

0.81

3±

0.12

20.

560

±0.

067

1.01

±0.

050.

724

±0.

016

0.78

5±

0.05

71.

41±

0.03

Eu

pp

m0.

357

±0.

020

0.31

1±

0.02

50.

665

±0.

013

0.32

1±

0.03

80.

269

±0.

034

0.43

6±

0.06

10.

350

±0.

014

0.61

1±

0.04

70.

353

±0.

021

0.36

5±

0.03

90.

464

±0.

014

0.37

7±

0.01

50.

300

±0.

017

0.52

5±

0.02

60.

391

±0.

004

0.39

6±

0.02

10.

772

±0.

033

Gd

pp

m1.

38±

0.06

1.34

±0.

112.

47±

0.06

1.09

±0.

100.

956

±0.

096

1.98

±0.

251.

29±

0.05

1.96

±0.

181.

31±

0.16

1.49

±0.

111.

45±

0.10

1.54

±0.

131.

15±

0.08

1.47

±0.

051.

30±

0.02

1.54

±0.

223.

11±

0.20

Tb

pp

mn

.a.

0.36

6±

0.02

0n

.a.

n.a

.0.

225

±0.

011

0.44

3±

0.02

70.

310

±0.

023

n.a

.0.

404

±0.

020

n.a

.n

.a.

0.42

0±

0.01

80.

264

±0.

009

0.26

4±

0.00

40.

286

±0.

015

0.32

2±

0.02

00.

659

±0.

019

Dy

pp

m2.

46±

0.15

3.24

±0.

305.

04±

0.14

2.00

±0.

191.

84±

0.05

3.78

±0.

152.

43±

0.13

2.90

±0.

323.

54±

0.24

3.07

±0.

322.

31±

0.22

3.52

±0.

162.

26±

0.10

1.76

±0.

032.

35±

0.03

2.55

±0.

175.

07±

0.18

Ho

pp

m0.

626

±0.

040

0.89

0±

0.06

41.

35±

0.07

0.48

9±

0.07

00.

449

±0.

032

0.95

5±

0.01

30.

603

±0.

033

0.58

4±

0.06

20.

983

±0.

044

0.83

0±

0.10

10.

474

±0.

033

0.95

0±

0.03

40.

568

±0.

029

0.34

2±

0.00

60.

540

±0.

007

0.58

3±

0.02

91.

19±

0.04

3

Er

pp

m1.

92±

0.13

3.03

±0.

294.

65±

0.22

1.41

±0.

201.

40±

0.08

3.10

±0.

141.

86±

0.08

1.34

±0.

223.

12±

0.06

2.43

±0.

211.

32±

0.10

3.18

±0.

211.

76±

0.08

0.90

±0.

041.

58±

0.06

1.68

±0.

013.

11±

0.16

Tm

pp

mn

.a.

0.50

9±

0.04

4n

.a.

n.a

.0.

226

±0.

027

0.47

2±

0.03

40.

291

±0.

008

n.a

.0.

546

±0.

010

n.a

.n

.a.

0.52

6±

0.02

70.

276

±0.

004

0.11

0±

0.00

50.

224

±0.

012

0.26

5±

0.01

10.

420

±0.

007

Yb

pp

m2.

27±

0.19

3.97

±0.

536.

36±

0.38

1.63

±0.

331.

79±

0.14

3.63

±0.

222.

21±

0.11

1.07

±0.

164.

09±

0.17

2.81

±0.

471.

45±

0.08

4.46

±0.

492.

03±

0.13

0.85

±0.

028

1.61

±0.

101.

88±

0.11

2.50

±0.

11

Lu

pp

m0.

351

±0.

029

0.62

4±

0.06

41.

02±

0.10

0.22

7±

0.06

30.

281

±0.

037

0.55

8±

0.04

50.

348

±0.

027

0.13

9±

0.01

60.

665

±0.

034

0.39

8±

0.06

00.

210

±0.

015

0.69

9±

0.07

30.

300

±0.

014

0.12

9±

0.01

00.

229

±0.

001

0.29

0±

0.01

00.

297

±0.

014

Hf

pp

m0.

438

±0.

072

0.44

4±

0.10

41.

24±

0.06

0.19

8±

0.05

70.

251

±0.

073

0.45

2±

0.10

10.

308

±0.

061

0.30

7±

0.07

00.

368

±0.

033

0.42

2±

0.18

40.

314

±0.

035

0.41

2±

0.05

30.

327

±0.

089

0.46

8±

0.01

80.

416

±0.

029

0.41

1±

0.00

21.

19±

0.07

Ta

pp

mb

.d.l

.b

.d.l

.0.

015

±0.

003

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.01

40.

015

±0.

002

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Pb

pp

m0.

036

±0.

006

0.28

8±

0.41

70.

114

±0.

044

0.11

9±

0.09

10.

038

b.d

.l.

0.16

9±

0.07

80.

066

±0.

037

b.d

.l.

1.10

±1.

050.

032

±0.

002

1.96

0±

0.00

0.02

1±

0.00

1b

.d.l

.0.

023

b.d

.l.

b.d

.l.

Th

pp

m0.

020

b.d

.l.

0.01

7b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.0.

023

±0.

002

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Up

pm

0.01

60.

462

±0.

445

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.01

9b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.

Sam

ple

RV

07-4

1H

RV

77b

imin

XR

V6

XR

V6

RV

07-9

aR

V07

-9b

RV

73-1

2R

V07

-8R

V07

-12

RV

07-3

0R

V07

-31

RV

07-3

3R

V07

-34

RV

07-3

6R

V07

-37

RV

07-6

6H

RV

77m

acr

ocx

N3

33

46

69

76

78

55

33

53

Du

sty

garn

etC

lean

garn

et

Ele

men

t

Li

pp

m1.

05±

0.12

1.06

±0.

141.

40±

0.93

0.56

6±

0.11

10.

961

±0.

075

1.05

±0.

191.

05±

0.13

0.71

3±

0.05

20.

977

±0.

117

0.82

2±

0.37

20.

695

±0.

115

0.64

0±

0.08

70.

560

±0.

077

0.74

0±

0.04

30.

681

±0.

041

0.26

3±

0.01

1.45

±0.

18

Pp

pm

103

±2

166

±24

126

±4

108

±7

158

±22

212

±22

39.7

±20

.911

.3±

4.2

76.8

±32

.620

.6±

3.7

40.8

±4.

525

.9±

4.1

31.3

±1.

2167

.7±

5.3

58.3

±1.

7438

.8±

0.7

36.4

±6.

9

Kp

pm

b.d

.l.

4.62

±2.

1516

9±

851.

90b

.d.l

.2.

142.

77±

1.08

n.a

.1.

63b

.d.l

.1.

03b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.

Ti

pp

m17

61±

141

1393

±46

2210

±55

1775

±10

916

86±

7917

47±

2511

28±

9010

17±

5895

9±

181

673

±93

745

±11

286

7±

157

1007

±14

577

8±

3181

1±

1168

6±

117

17±

14

Vp

pm

80.4

±0.

995

.1±

6.6

132

±4

114

±6

142

±11

139

±6

159

±10

.155

205

±8

221

±19

110

±7

164

±5

186

±4

268

±18

130

±2

96.8

±1.

219

7±

195

.5±

1.5

Cr

pp

m12

61±

2912

37±

8841

3±

3440

7±

1317

65±

362

841

±49

1913

±78

n.a

.99

1±

6749

1±

1238

2±

1721

6±

1021

7±

1073

9±

5843

6±

1213

88±

308

1272

±40

Ni

pp

m49

.4±

1.22

546

.5±

3.7

31.0

±1.

831

.8±

1.2

36.6

±4.

450

.4±

6.1

55.0

±1.

813

.0±

1.1

38.7

±2.

143

.6±

1.9

29.3

±1.

724

.0±

0.6

15.9

±0.

858

.6±

1.0

36.0

±0.

938

.6±

0.3

50.7

±0.

1

Cu

pp

m0.

773

±0.

134

0.82

0±

0.03

30.

700

±0.

149

1.28

±0.

850.

888

±0.

155

1.91

±2.

412.

31±

0.22

n.a

.1.

83±

0.12

1.88

±0.

422.

38±

0.27

2.54

±0.

205.

07±

0.45

2.23

±0.

141.

93±

0.11

0.30

3±

0.03

31.

76±

0.08

Rb

pp

mb

.d.l

.b

.d.l

.0.

587

±0.

343

0.05

b.d

.l.

0.03

2±

0.00

5b

.d.l

.0.

024

b.d

.l.

b.d

.l.±

0.02

7b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.

Sr

pp

m0.

553

±0.

011

0.75

6±

0.10

23.

86±

0.61

1.36

±0.

030.

643

±0.

051

0.44

4±

0.10

00.

080

±0.

056

0.07

9±

0.02

90.

109

±0.

010

0.09

0±

0.09

50.

091

±0.

033

0.08

1±

0.01

30.

123

±0.

012

0.09

0±

0.01

0.05

6±

0.01

50.

020

±0.

002

1.12

±0.

08

Yp

pm

12.8

±0.

419

.9±

2.9

22.6

±0.

625

.5±

1.1

23.7

±6.

728

.6±

1.99

37.9

±2.

056

.6±

5.6

49.8

±3.

426

.8±

1.1

27.2

±2.

424

.2±

2.1

28.6

±5.

4045

.5±

1.9

32.6

±0.

825

.5±

0.4

17.6

±0.

4

Zr

pp

m12

.9±

0.5

14.3

±2.

830

.1±

0.8

31.7

±1.

019

24.3

±11

.327

.8±

1.30

1.82

±0.

251.

23±

0.15

5.79

±0.

921.

12±

0.13

1.00

±0.

770.

311

±0.

039

0.8

±0.

084.

09±

0.07

3.24

±0.

142.

7±

0.05

12.8

±0.

3

Nb

pp

mb

.d.l

.0.

045

0.20

1±

0.03

3b

.d.l

.b

.d.l

.0.

026

±0.

007

0.02

9±

0.00

5b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.

Cs

pp

m0.

592

0.05

00.

037

±0.

02b

.d.l

.0.

016

±0.

003

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Ba

pp

m0.

260

0.34

010

.8±

5.3

b.d

.l.

b.d

.l.

b.d

.l.

0.16

9±

0.02

9b

.d.l

.b

.d.l

.0.

202

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

La

pp

m0.

018

±0.

001

b.d

.l.

0.42

0±

0.08

40.

050

±0.

009

0.02

3±

0.00

80.

020

±0.

005

0.04

4±

0.01

0b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.0.

008

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Ce

pp

m0.

107

±0.

034

0.15

9±

0.01

51.

19±

0.14

0.56

7±

0.02

60.

194

±0.

013

0.12

2±

0.04

50.

061

±0.

039

0.01

30.

017

±0.

003

0.04

4b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.0.

100

±0.

024

Pr

pp

m0.

036

±0.

007

0.06

5±

0.00

80.

229

±0.

018

0.23

1±

0.01

70.

079

±0.

012

0.05

1±

0.01

9b

.d.l

.0.

013

0.02

3±

0.00

4b

.d.l

.b

.d.l

.b

.d.l

.0.

009

±0.

002

b.d

.l.

b.d

.l.

b.d

.l.

0.05

0±

0.01

6

Nd

pp

m0.

341

±0.

049

0.90

7±

0.12

72.

06±

0.09

2.41

±0.

060.

865

±0.

122

0.54

2±

0.12

30.

086

±0.

010

0.13

2±

0.03

60.

493

±0.

054

b.d

.l.

0.09

0±

0.01

80.

068

0.11

9±

0.02

70.

210

±0.

007

0.14

2±

0.01

70.

054

±0.

005

0.69

6±

0.02

9

Sm

pp

m0.

348

±0.

029

0.68

6±

0.16

91.

24±

0.05

1.57

±0.

060.

646

±0.

123

0.72

5±

0.08

10.

227

±0.

037

0.53

7±

0.05

81.

47±

0.04

0.35

6±

0.04

60.

430

±0.

057

0.33

8±

0.06

00.

406

±0.

015

0.85

3±

0.00

90.

378

±0.

048

0.17

5±

0.01

20.

910

±0.

131

(conti

nued

on

nex

tpage)

Roberts Victor eclogites: A metasomatic history 6937

Tab

le4

(conti

nued

)

Sam

ple

RV

07-4

1H

RV

77b

imin

XR

V6

XR

V6

RV

07-9

aR

V07

-9b

RV

73-1

2R

V07

-8R

V07

-12

RV

07-3

0R

V07

-31

RV

07-3

3R

V07

-34

RV

07-3

6R

V07

-37

RV

07-6

6H

RV

77m

acr

ocx

Eu

pp

m0.

250

±0.

025

0.38

9±

0.02

30.

624

±0.

016

0.88

9±

0.02

90.

324

±0.

063

0.45

5±

0.05

50.

255

±0.

031

0.44

2±

0.02

70.

954

±0.

028

0.34

3±

0.03

20.

480

±0.

023

0.37

3±

0.02

90.

369

±0.

023

0.60

9±

0.02

30.

444

±0.

020

0.19

5±

0.02

00.

598

±0.

030

Gd

pp

m0.

860

±0.

054

1.54

±0.

212.

10±

0.09

3.06

±0.

091.

39±

0.22

2.13

±0.

311.

57±

0.10

2.56

±0.

134.

42±

0.21

1.47

±0.

081.

85±

0.09

1.47

±0.

141.

61±

0.19

3.02

±0.

121.

95±

0.13

1.06

±0.

041.

90±

0.03

Tb

pp

m0.

210

±0.

014

0.34

6±

0.03

40.

493

±0.

008

0.62

1±

0.02

20.

370

±0.

095

0.55

8±

0.07

40.

481

±0.

028

n.a

.1.

02±

0.03

0.46

9±

0.01

20.

503

±0.

027

0.43

3±

0.01

70.

461

±0.

058

0.78

0±

0.04

30.

558

±0.

029

0.37

1±

0.00

60.

406

±0.

040

Dy

pp

m1.

74±

0.09

2.97

±0.

273.

59±

0.19

4.49

±0.

163.

36±

0.85

4.42

±0.

485.

00±

0.23

7.55

±0.

558.

10±

0.29

3.97

±0.

164.

26±

0.25

3.81

±0.

354.

08±

0.67

6.76

±0.

294.

84±

0.19

3.32

±0.

023.

05±

0.06

Ho

pp

m0.

500

±0.

022

0.79

0±

0.11

90.

856

±0.

030

0.99

0±

0.02

00.

932

±0.

237

1.10

±0.

111.

39±

0.06

2.23

±0.

191.

88±

0.11

1.05

±0.

041.

11±

0.11

0.97

0±

0.10

01.

11±

0.19

1.75

0±

0.09

1.24

±0.

050.

993

±0.

028

0.70

1±

0.02

2

Er

pp

m1.

62±

0.04

2.76

±0.

412.

55±

0.09

2.79

±0.

153.

25±

0.83

3.36

±0.

294.

81±

0.26

7.68

±0.

735.

41±

0.52

3.36

±0.

263.

39±

0.39

3.02

±0.

363.

64±

0.84

5.39

±0.

303.

94±

0.06

3.14

±0.

112.

11±

0.10

Tm

pp

m0.

290

±0.

017

0.41

4±

0.07

70.

401

±0.

006

0.43

4±

0.02

80.

551

±0.

130

0.53

1±

0.04

50.

768

±0.

049

n.a

.0.

803

±0.

102

0.54

2±

0.04

10.

546

±0.

085

0.46

9±

0.05

30.

572

±0.

127

0.83

3±

0.05

60.

615

±0.

021

0.54

1±

0.01

20.

306

±0.

017

Yb

pp

m2.

09±

0.15

3.37

±0.

523.

00±

0.11

3.26

±0.

114.

54±

0.83

3.90

±0.

245.

92±

0.33

10.5

±1.

05.

79±

0.88

4.26

±0.

524.

25±

0.62

3.62

±0.

374.

56±

0.87

6.09

±0.

294.

74±

0.05

4.19

±0.

062.

22±

0.29

Lu

pp

m0.

341

±0.

030

0.47

6±

0.10

00.

432

±0.

019

0.45

1±

0.03

80.

735

±0.

161

0.57

0±

0.04

30.

934

±0.

057

1.61

±0.

190.

826

±0.

143

0.60

7±

0.08

30.

618

±0.

120

0.50

9±

0.06

20.

689

±0.

153

0.95

3±

0.02

40.

717

±0.

040

0.64

8±

0.00

60.

362

±0.

02

Hf

pp

m0.

215

±0.

017

0.25

1±

0.07

90.

616

±0.

028

0.62

9±

0.02

70.

480

±0.

301

0.40

6±

0.03

40.

110

±0.

019

0.06

3±

0.01

70.

161

±0.

038

0.04

8±

0.00

70.

052

±0.

012

0.06

20.

081

±0.

021

0.12

4±

0.01

70.

121

±0.

127

±0.

003

0.30

5±

0.05

5

Ta

pp

mb

.d.l

.b

.d.l

.0.

015

±0.

001

b.d

.l.

0.01

3±

0.00

00.

044

±0.

000

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.01

0b

.d.l

.

Pb

pp

mb

.d.l

.b

.d.l

.0.

218

±0.

213

0.06

10.

073

±0.

046

0.05

5±

0.02

70.

033

±0.

004

0.06

9±

0.02

3b

.d.l

.0.

123

0.10

5±

0.09

40.

024

b.d

.l.

0.03

2±

0.00

2b

.d.l

.b

.d.l

.b

.d.l

.

Th

pp

mb

.d.l

.0.

050

0.05

0±

0.01

7b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.0.

017

±0.

002

b.d

.l.

b.d

.l.

b.d

.l.

0.01

1b

.d.l

.b

.d.l

.b

.d.l

.0.

066

Up

pm

b.d

.l.

0.04

60.

013

±0.

001

0.01

10.

014

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.01

90.

023

±0.

002

b.d

.l.

b.d

.l.

n.a

.=

no

tan

alys

ed.

b.d

.l.

=b

elo

wd

etec

tio

nli

mit

.

6938 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

Zr and Hf levels are mostly suprachondritic with ZrN

ranging from 1.79 to 12.25 and HfN from 0.81 to 6.93.The Zr/Hf ratio is quite consistent and varies from 1.40to 2.35; Hf and Zr are enriched compared to Type II gar-nets. Ba contents are generally higher in Type I garnets(ca 0.3 ppm) than in Type II in which Ba is mostly underthe detection limit. However some stronger enrichmentsin Ba can be seen in some samples. This is particularly evi-dent for the “dusty” garnets of XRV6, with Ba = 10.8 ppmwhile the average content is 0.42 ppm. In addition to the“dusty” garnets of XRV6, RV07-13, garnets in RV07-22and RV07-29b also show minor enrichment in Ba, whichmay also be due to the analysis of fluid inclusions in the“dusty” garnet.

K contents are quite low, with most values ranging from1.8 to 14.8 ppm. Higher values (e.g. 169 ppm) also corre-spond to samples with higher values for Ba, confirming thatimpurities (dusty aspect; fluid and solid inclusions) in thegarnet are responsible for some of the strongest enrich-ments in incompatible elements. This is clearly evident bycomparison with the Ba and K contents of the clear garnetsin XRV6, which are below detection limits. Concentrationsof transition metals such as Ni and Cu show significantranges. Ni contents in garnets from Type I eclogites arequite similar to those of Type II garnets, ranging from11.2 to 80.7 ppm, while the Cu contents are much lowerthan in Type II and range from 0.3 to 1.54 ppm.

5.2.2. Clinopyroxene

5.2.2.1. Type II. REE patterns of clinopyroxenes in Type IIeclogites (Fig. 6a) show more variation than those of Type Iclinopyroxenes (Fig. 6c). However, typical Type II patternsare still distinctive. They are strongly upward-convex withprogressive enrichment from the HREE to the MREE(3.2 6 GdN/LuN 6 60.8), but the top of the curve is centredon Eu or Sm. Then REE-normalised abundances decreasefrom Eu (or Sm) to La, defining a relatively steep slope(0.01 6 CeN/EuN 6 0.25). Whereas LaN in cpx of Type Ieclogites is suprachondritic, Type II values are always sub-chondritic and commonly below the detection limit of theinstrument (0.009 6 LaN 6 0.363). Type II LuN varies from0.095 to 0.72.

One of the principal characteristics of clinopyroxenefrom Type II eclogites is the quasi-absence of the strongSrN anomaly relative to MREE (Fig. 6b) seen in Type Icpx.. Only HRV77macro shows such a strongly markedanomaly (SrN = 17) with a Sr content of 205 ppm (Table 5),while the average for the other Type II cpx is only 30 ppm.Zr/HfN ratios are <1, ranging from 0.19 to 0.52 with ZrN

between 0.1 and 2.8, while HfN ranges from 0.5 to 6.9.Most of the samples have Ba contents below the detec-

tion limit (<0.1 ppm); where detectable, Ba ranges from0.1 to 0.9 ppm. Similarly, although K is often undetectable(Kmdl = 1 ppm), most of the samples have low K contentsvarying between 4 and 26 ppm. The only exception isHRV77macro (K = 1197 ppm), which will be discussed be-low. In terms of transition metals, NiN ranges from 0.009to 0.051 (153–840 ppm), ZnN from 0.121 to 0.224 (55–103 ppm) and CuN from 0.021 and 0.495 (3.5–83 ppm).

0.001

0.01

0.1

1

10

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Cpx

/CI c

hond

rites

c Type I cpx

HRV77bimin

Cpx

/CI c

hond

rites

a Type II cpx

0.001

0.01

0.1

1

10

100

CrNi

CuK TiRb

Cs BaLa

Ce PrNd Sm

EuSr GdDy

HoY

YbLu

ZrHf

NbTaPbTh

U0.0001

0.001

0.01

0.1

1

10

Cpx

/CI c

hond

rites

d Type I cpx

Cpx

/CI c

hond

rites

b Type II cpx

0.0001

0.001

0.01

0.1

1

10

100

HRV77macrocx

HRV77bimin

HRV77macrocx

Fig. 6. In situ trace-element compositions of Roberts Victor cpx normalised to chondrites. (a) REE patterns of Type II cpx; Type I cpxcompositions (grey field) from this study are shown for comparison. (b) Extended trace-element patterns of Type II cpx; Type I cpxcompositions (grey field) from this study are shown for comparison. (c) REE patterns of Type cpx. (d) Extended trace-element patterns ofType I cpx; note the characteristic positive Sr anomalies. Chondrites values from Anders and Grevesse (1989).

Roberts Victor eclogites: A metasomatic history 6939

5.2.2.2. Type I. Chondrite-normalised REE patterns of TypeI clinopyroxenes have similar shapes from sample to sample(Fig. 6c) and do not show EuN anomalies. The typical patternis upward-convex with a progressive enrichment from Lu toNd, reaching a maximum at Pr before decreasing to La. LaN/PrN ratios vary from 0.58 to 0.80 and GdN/LuN vary from5.81 to 48.50. Although the patterns are similar in shape,the absolute abundances range from 1 to 10 times chondritefor LaN and LuN varies from 0.1 to 1.

Type I cpx are characterised by a strong positive anom-aly in strontium (Fig. 6d). SrN varies from 10.2 to 33.6, cor-responding to Sr contents from 121 to 400 ppm. K variesfrom 695 to 1516 ppm, and Ba values range between 0.16and 3.8 ppm. Zr and Hf also show positive anomalies withZr from 9.2 to 55 ppm and Hf from 0.5 to 2.95 ppm. ZrN/HfN is always <1 with values between 0.38 and 0.78. TheType I clinopyroxenes show lower concentrations of transi-tion metals than Type II clinopyroxenes, with Ni rangingfrom 153 to 376 ppm, Zn from 36.5 to 89.6 ppm and Cufrom 3.1 to 17.4 ppm and also higher and more uniformTi concentrations than Type II.

Although the McCandless and Gurney classification(1989) was only based on the Na2O content of garnet andthe K2O content of cpx, the petrographic and geochemical re-sults for the two types described in this study, show that sev-eral other marked differences fit this classification (Table 6).

6. OXYGEN ISOTOPES

Oxygen-isotope compositions (expressed as d18O values)have been analysed in rutile- and inclusion-free garnets

from bimineralic Type I and Type II eclogites (Type I: 13values; Type II: 2 values; Table 3). d18O values of Type I gar-nets spread from +4.2& to +7.3&. The oxygen-isotopecompositions of garnet from two Type II eclogites are similarto those found in the literature (Macgregor and Manton,1986; Caporuscio, 1990; Schulze et al., 2000; Jacob et al.,2005) for similar rock-types, with d18ORV07-8 = +3.9& andd18ORV73-12 = +3.5&. d18O values of garnets from bothtypes of bimineralic eclogites (I and II) overlap the range ofd18O values for olivine (mean d18Oolivine: +5.18 ± 0.28&)in a depleted mantle (Mattey et al., 1994).

7. DISCUSSION

7.1. Trace-element modelling

The mafic nature of mantle eclogites and therefore theirchemical similarities with basalts and gabbros have logi-cally led many authors to interpret the eclogites as subduct-ed oceanic crust. However, although the major-elementcompositions of mantle eclogites are broadly similar tothose of oceanic basalts and gabbros, their trace-elementconcentrations are not as straightforwardly interpreted.

Modal analyses and trace-element data for garnet andcpx from the two types of Roberts Victor eclogites wereused to reconstruct the whole-rock trace-element composi-tion of each sample (Table 7), thus avoiding contaminationdue to kimberlite infiltration. As expected from the lowincompatible-element contents in both garnet and cpx fromType II eclogites, Type II whole-rocks display very depletedChondrite-normalised trace-element patterns (Fig. 7). Such

Tab

le5

Tra

ce-e

lem

ent

com

po

siti

on

so

fcl

ino

pyr

oxe

nes

.

Sam

ple

sR

V07

-1R

V07

-2R

V07

-3R

V07

-7R

V07

-11

RV

07-1

3R

V07

-14

RV

07-1

6R

V07

-17

RV

07-1

8R

V07

-19

RV

07-2

0R

V07

-22

RV

07-2

4R

V07

-29a

RV

07-2

9bR

V07

-40

N5

56

54

34

115

65

34

55

53

Ele

men

t

Li

pp

m8.

43±

0.39

11.2

±1.

33.

92±

1.94

9.00

±0.

249.

11±

0.07

7.98

±0.

0510

.7±

1.1

20.3

±2.

99.

57±

0.93

10.4

±0.

215

.9±

2.5

3.35

±0.

1411

.4±

0.2

10.5

±4.

88.

75±

0.36

8.48

±0.

801.

50±

0.25

Pp

pm

36.8

±3.

638

.0±

6.4

31.0

±1.

232

.3±

2.3

61.9

±12

.447

.0±

4.9

78.6

±17

.152

.4±

9.3

42.8

±4.

931

.2±

2.4

33.2

±3.

145

.3±

5.8

40.9

±4.

471

.1±

22.9

30.5

±1.

741

.0±

2.4

93.2

±4.

6

Kp

pm

1262

±15

1319

±15

0n

.a.

1166

±22

1291

±25

1093

±54

1432

±38

911

19±

4815

16±

118

967

±11

939

±49

992

±9

1063

±28

902

±34

1372

±32

1327

±32

690

±29

Ti

pp

m19

99±

2221

18±

5426

44±

8819

93±

818

02±

3523

29±

1119

71±

1618

47±

4322

04±

3120

20±

6318

95±

4781

5±

3622

78±

3817

89±

303

2130

±9

2118

±43

2376

±67

Vp

pm

351

±4

420

±37

462

±5

327

±10

306

±7

446

±5

373

±11

174

±16

316

±9

251

±9

311

±15

479

±3

260

±7

237

±86

386

±7

400

±11

558

±12

Cr

pp

m11

16±

4995

8±

111

n.a

.68

8±

1768

9±

1184

0±

210

04±

6267

7±

2210

87±

3769

0±

1971

4±

6420

0±

162

8±

1362

0±

9777

4±

6990

8±

5635

4±

12

Ni

pp

m31

6±

928

6±

4717

8±

1228

7±

819

7±

1517

7±

1028

1±

1434

0±

1526

6±

1131

7±

1732

2±

2315

3±

433

2±

937

6±

156

306

±0

301

±10

359

±7

Cu

pp

m8.

95±

0.15

9.27

±1.

68n

.a.

9.77

±0.

438.

42±

0.26

15.0

±0.

29.

88±

1.04

14.0

±1.

46.

17±

0.40

11.2

±0.

417

.4±

7.3

3.14

±0.

0820

.5±

0.5

11.9

±5.

618

.3±

0.7

18.1

±1.

06.

13±

3.46

Rb

pp

m0.

033

±0.

005

1.15

±1.

860.

305

±0.

335

0.01

90.

041

0.04

32.

720.

098

±0.

052

0.04

9±

0.02

20.

070

±0.

069

0.17

8±

0.13

7b

.d.l

.b

.d.l

.0.

067

0.03

50.

053

±0.

001

0.37

7±

0.04

6

Sr

pp

m25

6±

1023

4±

332

9±

1422

6±

323

8±

325

1±

822

8±

312

9±

921

0±

721

1±

714

4±

525

2±

322

6±

212

1±

6026

3±

627

4±

540

1±

3

Yp

pm

1.28

±0.

102.

38±

0.26

3.51

±0.

101.

38±

0.03

1.27

±0.

133.

13±

0.10

1.42

±0.

100.

455

±0.

077

1.89

±0.

081.

45±

0.08

0.55

2±

0.04

43.

12±

0.07

1.73

±0.

031.

40±

2.05

1.23

±0.

051.

17±

0.07

4.87

±0.

24

Zr

pp

m14

.6±

1.4

20.3

±3.

249

.5±

1.5

12.0

±0.

411

.3±

0.8

34.3

±1.

217

.7±

0.7

9.21

±1.

3130

.4±

1.5

14.7

±0.

912

.3±

0.7

10.6

±0.

318

.0±

1.2

13.8

±2.

918

.2±

1.2

17.9

±0.

755

.3±

1.3

Nb

pp

m0.

029

±0.

005

0.19

2±

0.31

30.

063

±0.

015

0.01

90.

022

±0.

008

0.03

5±

0.00

20.

067

±0.

059

0.02

5±

0.00

40.

033

±0.

004

0.02

9±

0.00

30.

032

0.04

8±

0.00

40.

034

±0.

005

0.02

2±

0.00

40.

027

±0.

003

0.04

6±

0.01

00.

347

Cs

pp

mb

.d.l

.0.

696

±0.

684

0.03

9±

0.00

0b

.d.l

.0.

041

b.d

.l.

0.02

60.

101

0.01

70.

082

±0.

070

0.02

2b

.d.l

.b

.d.l

.0.

040

±0.

016

b.d

.l.

b.d

.l.

0.61

6

Ba

pp

m0.

352

±0.

082

0.51

2±

0.26

70.

916

±0.

812

0.31

9±

0.08

20.

247

±0.

046

0.47

5±

0.05

53.

81±

6.15

0.16

0±

0.13

20.

378

±0.

037

0.31

8±

0.24

30.

281

±0.

280.

755

±0.

011

0.31

2±

0.05

01.

24±

1.45

0.30

2±

0.03

90.

296

±0.

032

2.76

±0.

10

La

pp

m1.

23±

0.06

1.35

±0.

123.

14±

0.13

1.03

±0.

051.

01±

0.10

1.38

±0.

081.

11±

0.09

0.36

±0.

048

1.29

±0.

110.

95±

0.03

80.

54±

0.03

72.

56±

0.03

1.01

±0.

020.

344

±0.

162

1.08

±0.

041.

13±

0.06

2.09

±0.

12

Ce

pp

m5.

14±

0.26

6.33

±0.

2811

.2±

0.3

4.44

±0.

144.

60±

0.17

6.19

±0.

424.

41±

0.13

1.69

±0.

065.

01±

0.55

3.89

±0.

132.

35±

0.08

10.4

±0.

14.

21±

0.13

1.68

±0.

754.

56±

0.05

4.76

±0.

1412

.5±

0.4

Pr

pp

m0.

928

±0.

055

1.06

±0.

042.

00±

0.06

0.80

8±

0.03

80.

797

±0.

038

1.23

±0.

030.

772

±0.

014

0.30

1±

0.02

40.

840

±0.

094

0.75

5±

0.05

60.

415

±0.

033

1.63

±0.

010.

840

±0.

012

0.33

8±

0.11

60.

919

±0.

033

0.94

0±

0.02

83.

09±

0.08

Nd

pp

m4.

85±

0.32

5.24

±0.

3210

.52

±0.

34.

19±

0.14

4.14

±0.

356.

32±

0.10

4.04

±0.

091.

62±

0.20

4.23

±0.

423.

84±

0.29

2.14

±0.

157.

95±

0.24

4.45

±0.

161.

95±

0.42

4.85

±0.

264.

90±

0.09

17.9

±0.

4

Sm

pp

m1.

12±

0.18

1.20

±0.

142.

03±

0.09

0.96

3±

0.16

70.

906

±0.

056

1.37

±0.

000.

965

±0.

057

0.36

2±

0.05

91.

07±

0.09

0.91

3±

0.07

30.

534

±0.

040

1.69

±0.

040.

979

±0.

041

0.56

3±

0.15

71.

05±

0.08

1.13

±0.

064.

18±

0.25

Eu

pp

m0.

326

±0.

022

0.35

5±

0.02

00.

569

±0.

026

0.30

7±

0.02

00.

291

±0.

028

0.44

2±

0.01

40.

323

±0.

026

0.13

7±

0.02

00.

345

±0.

028

0.30

2±

0.02

80.

165

±0.

009

0.51

1±

0.02

60.

298

±0.

005

0.23

5±

0.16

00.

304

±0.

001

0.30

3±

0.01

31.

26±

0.04

8

Gd

pp

m0.

670

±0.

100

0.89

7±

0.08

61.

32±

0.04

0.67

5±

0.04

70.

558

±0.

062

1.01

±0.

050.

657

±0.

036

0.28

8±

0.07

00.

750

±0.

075

0.61

4±

0.05

00.

323

±0.

062

1.19

±0.

030.

727

±0.

022

0.41

2±

0.32

40.

668

±0.

051

0.61

5±

0.04

42.

88±

0.20

Tb

pp

m0.

079

±0.

006

0.11

7±

0.01

5n

.a.

0.08

8±

0.01

30.

082

±0.

012

0.12

6±

0.00

40.

089

±0.

008

0.03

4±

0.00

60.

099

±0.

006

0.08

5±

0.01

00.

049

±0.

007

0.15

4±

0.00

60.

093

±0.

004

0.05

5±

0.05

30.

074

±0.

001

0.07

5±

0.00

60.

327

±0.

014

Dy

pp

m0.

377

±0.

047

0.60

4±

0.07

80.

931

±0.

045

0.37

8±

0.04

00.

331

±0.

024

0.82

2±

0.07

00.

409

±0.

042

0.17

6±

0.04

30.

524

±0.

042

0.40

7±

0.04

00.

166

±0.

025

0.83

4±

0.03

10.

459

±0.

015

0.34

6±

0.39

10.

321

±0.

008

0.38

0±

0.03

21.

51±

0.13

Ho

pp

m0.

053

±0.

010

0.10

6±

0.00

80.

151

±0.

010

0.05

7±

0.00

60.

062

±0.

010

0.12

6±

0.00

50.

065

±0.

003

0.02

2±

0.00

80.

079

±0.

014

0.06

9±

0.00

60.

022

±0.

004

0.12

7±

0.00

70.

066

±0.

003

0.06

0±

0.07

20.

045

±0.

003

0.05

6±

0.01

00.

192

±0.

017

Er

pp

m0.

125

±0.

018

0.21

8±

0.03

70.

327

±0.

040

0.11

4±

0.02

00.

137

±0.

051

0.30

8±

0.03

60.

126

±0.

012

0.05

7±

0.00

50.

175

±0.

021

0.12

1±

0.03

20.

060

±0.

007

0.30

2±

0.04

10.

173

±0.

017

0.57

80.

100

0.11

8±

0.01

50.

382

±0.

017

Tm

pp

m0.

015

±0.

004

0.02

9±

0.00

6n

.a.

0.01

4±

0.00

20.

010

±0.

003

0.03

6±

0.00

30.

016

±0.

006

0.01

3±

0.00

10.

022

±0.

001

0.01

5±

0.00

20.

006

±0.

001

0.02

7±

0.00

40.

018

±0.

003

0.08

70.

012

b.d

.l.

0.03

2±

0.00

2

Yb

pp

m0.

091

±0.

001

0.14

1±

0.01

90.

201

±0.

029

0.07

9±

0.01

70.

132

±0.

073

0.19

9±

0.02

90.

092

±0.

021

0.06

5±

0.00

00.

110

±0.

005

0.10

5±

0.01

20.

108

0.20

9±

0.06

10.

079

±0.

008

0.25

7±

0.24

7b

.d.l

.b

.d.l

.0.

171

±0.

030

Lu

pp

mb

.d.l

.0.

018

±0.

002

0.02

9±

0.00

50.

010

±0.

002

0.01

60.

020

0.01

2b

.d.l

.0.

011

±0.

001

0.01

7±

0.00

2b

.d.l

.0.

029

±0.

006

0.01

60.

088

±0.

000

0.00

9±

0.00

10.

021

±0.

001

0.02

5±

0.00

1

Hf

pp

m0.

818

±0.

135

1.25

±0.

262.

95±

0.15

0.63

4±

0.05

50.

599

±0.

077

2.89

±0.

281.

07±

0.03

0.47

9±

0.10

01.

70±

0.27

0.80

9±

0.09

10.

682

±0.

034

0.59

6±

0.05

10.

937

±0.

115

0.68

6±

0.13

21.

02±

0.12

1.01

±0.

022.

96±

0.25

Ta

pp

m0.

010

0.00

8±

0.00

30.

012

±0.

001

b.d

.l.

b.d

.l.

b.d

.l.

0.01

80.

009

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Pb

pp

m0.

408

±0.

053

0.96

1±

0.45

40.

627

±0.

040

0.42

3±

0.03

40.

474

±0.

026

0.56

3±

0.03

50.

490

±0.

029

0.26

1±

0.05

50.

643

±0.

028

0.42

9±

0.05

00.

285

±0.

041

0.82

2±

0.06

80.

465

±0.

025

0.18

7±

0.07

40.

526

±0.

001

0.54

0±

0.03

73.

12±

0.56

Th

pp

m0.

010

0.01

10.

020

±0.

006

b.d

.l.

b.d

.l.

b.d

.l.

0.02

3±

0.00

5b

.d.l

.b

.d.l

.b

.d.l

.0.

008

0.02

3b

.d.l

.b

.d.l

.b

.d.l

.0.

023

±0.

001

b.d

.l.

Up

pm

0.01

00.

366

±0.

498

0.01

8±

0.00

4b

.d.l

.b

.d.l

.0.

026

b.d

.l.

0.01

9b

.d.l

.b

.d.l

.0.

053

±0.

046

b.d

.l.

b.d

.l.

0.01

2b

.d.l

.b

.d.l

.b

.d.l

.

Sam

ple

sR

V07

-41

XR

V6

HR

V77

bim

inR

V07

-9a

RV

07-9

bR

V73

-12

RV

07-8

RV

07-1

2R

V07

-30

RV

07-3

1R

V07

-33

RV

07-3

4R

V07

-36

RV

07-3

7R

V07

-66

HR

V77

ma

cro

cx

N3

33

44

57

69

76

43

46

6

Ele

men

t

Li

pp

m6.

97±

0.37

5.16

±0.

198.

28±

0.72

6.49

±0.

165.

66±

0.58

9.88

±1.

3110

.3±

10.3

9.08

±1.

1714

.8±

1.9

12.8

±0.

810

.5±

0.9

10.2

±0.

29.

04±

0.70

12.1

±0.

10.

26±

0.01

14.6

±0.

3

Pp

pm

51.5

±9.

435

.7±

0.4

40.6

±4.

033

.5±

7.4

44.4

±8.

513

.0±

5.5

6.73

±6.

7314

.8±

4.1

8.72

±2.

2623

.9±

2.7

17.5

±2.

522

.2±

2.2

40.9

±3.

931

.2±

4.0

38.8

±0.

718

.8±

7.0

Kp

pm

1513

±52

1046

±40

951

±32

1017

±21

937

±18

26.0

±13

.94.

27±

4.27

6.24

±2.

5214

.1±

5.1

b.d

.l.

23.9

±29

.5b

.d.l

.b

.d.l

.b

.d.l

.b

.d.l

.11

97±

6

Ti

pp

m13

11±

101

2239

±54

2114

±42

1722

±62

1628

±64

1002

±69

1374

±13

7492

4±

154

1004

±38

1027

±44

1010

±25

1386

±27

749

±10

1765

±92

668

6±

118

78±

62

Vp

pm

265

±18

419

±11

385

±10

377

±6

323

±8

392

±19

444

±44

443

0±

1338

3±

2646

6±

1245

0±

954

4±

1032

0±

731

2±

1619

7±

0.2

290

±1

Cr

pp

m12

06±

3373

2±

2299

1±

8513

34±

6059

9±

8212

76±

8215

1±

151

643

±22

562

±45

371

±10

188

±5

202

±2

564

±61

480

±16

1388

±30

814

69±

64

Ni

pp

m32

5±

1920

6±

724

3±

1422

6±

435

8±

3260

5±

2615

3±

153

589

±15

578

±56

388

±8

292

±8

174

±3

834

±6

449

±12

38.3

±0.

835

9±

10

Cu

pp

m11

.2±

0.9

9.79

±8.

288.

11±

0.88

5.35

±0.

684.

00±

0.20

52.6

±4.

240

.8±

40.8

48.4

±5.

033

.0±

4.9

39.7

±1.

539

.3±

2.0

83.2

±2.

051

.4±

1.6

42.6

±0.

90.

154

±0.

021

23.1

±0.

2

Rb

pp

m0.

581

0.06

80.

074

±0.

005

0.16

6±

0.19

4b

.d.l

.0.

150

±0.

040

0.12

8±

0.12

80.

073

±0.

011

0.05

2±

0.02

00.

022

0.10

9±

0.07

7b

.d.l

.±

b.d

.l.

b.d

.l.

b.d

.l.

0.06

5±

0.01

2

Sr

pp

m34

3±

727

1±

1020

8±

631

9±

630

7±

925

.9±

0.9

11.0

±11

.059

.9±

2.2

15.2

±0.

520

.8±

0.4

18.7

±1.

410

.6±

0.5

91.8

±0.

916

.3±

0.4

0.02

0±

0.00

220

5±

5

Yp

pm

2.67

±0.

241.

52±

0.09

1.81

±0.

033.

05±

0.06

3.69

±0.

114.

16±

0.39

1.07

±1.

072.

78±

0.40

0.84

2±

0.04

60.

690

±0.

053

0.62

9±

0.04

00.

575

±0.

092

4.06

±0.

231.

18±

0.07

25.5

±0.

40.

807

±0.

055

Zr

pp

m17

.0±

1.7

22.2

±1.

517

.4±

1.5

37.4

±2.

133

.2±

1.5

5.64

±0.

441.

98±

1.98

15.5

±1.

03.

19±

2.08

1.48

±0.

130.

577

±0.

051

0.82

9±

0.05

111

.6±

0.3

6.96

±0.

232.

66±

0.05

11.5

±0.

4

Nb

pp

m0.

033

±0.

004

0.07

2±

0.01

4b

.d.l

.0.

049

±0.

009

0.06

6±

0.00

50.

022

±0.

004

0.03

0±

0.03

00.

015

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.03

0±

0.00

1b

.d.l

.b

.d.l

.b

.d.l

.

Cs

pp

mb

.d.l

.b

.d.l

.b

.d.l

.0.

012

±0.

001

2.47

0.89

1±

1.39

10.

059

±0.

059

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

Ba

pp

m0.

649

±0.

051

0.54

7±

0.02

50.

540

±0.

230

0.71

0±

0.04

90.

648

±0.

063

0.37

0±

0.16

30.

313

±0.

313

0.12

0±

0.00

60.

130

±0.

008

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

b.d

.l.

0.29

5±

0.08

2

La

pp

m1.

81±

0.05

2.01

±0.

151.

04±

0.15

2.90

±0.

033.

04±

0.08

0.04

6±

0.03

50.

01±

0.01

30.

021

±0.

003

b.d

.l.

b.d

.l.

b.d

.l.

0.01

4b

.d.l

.b

.d.l

.b

.d.l

.0.

133

±0.

015

Ce

pp

m7.

18±

0.15

9.00

±0.

654.

90±

0.49

12.1

±0.

112

.1±

0.3

0.08

6±

0.08

3b

.d.l

.0.

422

±0.

019

0.02

1±

0.00

50.

013

±0.

003

0.02

1±

0.01

50.

022

±0.

006

0.23

9±

0.00

70.

026

±0.

001

b.d

.l.

0.64

±0.

010

Pr

pp

m1.

34±

0.02

1.49

±0.

040.

915

±0.

089

2.04

±0.

022.

00±

0.09

0.02

5±

0.01

10.

009

±0.

009

0.26

4±

0.01

30.

012

±0.

003

0.00

9±

0.00

10.

011

±0.

001

0.01

0±

0.00

10.

205

±0.

003

b.d

.l.

b.d

.l.

0.21

5±

0.01

1

Nd

pp

m6.

98±

0.20

6.97

±0.

604.

45±

0.31

10.3

±0.

39.

75±

0.55

0.40

1±

0.06

50.

167

±0.

167

3.00

3±

0.12

0.12

0±

0.03

00.

161

±0.

033

0.11

9±

0.01

10.

100

±0.

033

2.73

±0.

140.

255

±0.

032

0.05

4±

0.00

51.

58±

0.14

Sm

pp

m1.

46±

0.05

1.24

±0.

051.

04±

0.11

1.90

±0.

141.

91±

0.08

0.56

4±

0.04

90.

164

±0.

164

1.62

8±

0.04

0.20

4±

0.04

40.

225

±0.

032

0.17

3±

0.02

00.

088

±0.

012

1.95

±0.

120.

360

±0.

038

0.17

5±

0.01

20.

607

±0.

047

Eu

pp

m0.

543

±0.

028

0.39

0±

0.02

50.

311

±0.

023

0.57

2±

0.01

80.

595

±0.

028

0.32

0±

0.03

30.

076

±0.

076

0.56

9±

0.01

40.

122

±0.

020

0.12

8±

0.01

30.

085

±0.

016

0.05

2±

0.00

30.

761

±0.

040

0.16

1±

0.01

50.

195

±0.

020

0.23

7±

0.02

5

(conti

nued

on

nex

tpage)

6940 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

Tab

le5

(conti

nued

)

Sam

ple

sR

V07

-41

XR

V6

HR

V77

bim

inR

V07

-9a

RV

07-9

bR

V73

-12

RV

07-8

RV

07-1

2R

V07

-30

RV

07-3

1R

V07

-33

RV

07-3

4R

V07

-36

RV

07-3

7R

V07

-66

HR

V77

ma

cro

cx

Gd

pp

m1.

09±

0.06

0.93

3±

0.05

40.

720

±0.

029

1.27

±0.

101.

44±

0.06

1.16

3±

0.07

0.28

1±

0.28

11.

58±

0.07

0.31

8±

0.05

10.

269

±0.

019

0.25

3±

0.03

80.

130

±0.

037

2.03

±0.

070.

377

±0.

150

1.06

±0.

040.

432

±0.

050

Tb

pp

m0.

129

±0.

009

0.08

9±

0.01

70.

084

±0.

007

0.15

8±

0.00

80.

194

±0.

008

0.19

0±

0.01

60.

038

±0.

038

0.18

2±

0.01

20.

050

±0.

008

0.04

6±

0.00

60.

031

±0.

009

0.02

7±

0.00

50.

272

±0.

009

0.05

3±

0.00

40.

371

±0.

006

0.05

4±

0.00

4

Dy

pp

m0.

690

±0.

057

0.38

4±

0.02

70.

352

±0.

091

0.79

9±

0.02

80.

994

±0.

046

1.06

0±

0.12

0.22

8±

0.22

80.

883

±0.

098

0.24

4±

0.05

00.

190

±0.

041

0.16

8±

0.03

40.

133

±0.

025

1.29

±0.

110.

311

±0.

024

3.32

±0.

020.

225

±0.

070

Ho

pp

m0.

100

±0.

014

0.06

1±

0.01

90.

068

±0.

010

0.13

9±

0.00

50.

167

±0.

006

0.15

7±

0.01

30.

042

±0.

042

0.11

5±

0.01

70.

037

±0.

006

0.03

2±

0.00

50.

023

±0.

004

0.02

3±

0.00

30.

186

±0.

016

0.05

6±

0.01

00.

993

±0.

028

0.03

2±

0.00

9

Er

pp

m0.

251

±0.

059

0.17

5±

0.02

60.

238

±0.

019

0.28

4±

0.02

00.

355

±0.

034

0.37

7±

0.05

50.

084

±0.

084

0.18

1±

0.02

60.

101

±0.

032

0.07

3±

0.01

10.

090

±0.

017

0.06

0±

0.02

50.

385

±0.

030

0.14

8±

0.00

23.

14±

0.11

0.13

3±

0.00

0

Tm

pp

m0.

031

±0.

003

0.01

90.

031

±0.

001

0.02

9±

0.00

30.

037

±0.

007

0.03

6±

0.00

70.

016

±0.

016

0.02

1±

0.00

70.

013

±0.

001

b.d

.l.

0.01

2±

0.00

30.

009

±0.

002

0.04

1±

0.00

5b

.d.l

.0.

541

±0.

012

b.d

.l.

Yb

pp

m0.

254

±0.

071

0.10

0±

0.01

50.

187

±0.

022

0.18

9±

0.01

40.

211

±0.

025

0.18

0±

0.02

80.

082

±0.

082

0.09

4±

0.01

40.

072

±0.

009

0.06

3±

0.00

60.

099

±0.

038

0.04

7±

0.00

50.

177

±0.

029

b.d

.l.

4.19

±0.

06b

.d.l

.

Lu

pp

m0.

024

±0.

007

0.01

1b

.d.l

.0.

024

±0.

001

0.02

8±

0.00

30.

033

±0.

003

0.01

7±

0.01

70.

016

±0.

001

b.d

.l.

0.00

7±

0.00

00.

009

0.00

7b

.d.l

.b

.d.l

.0.

648

±0.

006

b.d

.l.

Hf

pp

m0.

946

±0.

109

1.38

±0.

141.

08±

0.17

92.

27±

0.17

1.80

±0.

060.

595

±0.

072

0.25

0±

0.25

01.

24±

0.08

0.29

0±

0.03

80.

184

±0.

028

0.09

3±

0.01

50.

139

±0.

012

0.87

3±

0.01

80.

553

±0.

019

0.12

7±

0.00

30.

722

±0.

095

Ta

pp

mb

.d.l

.0.

014

±0.

003

0.04

5±

0.00

40.

007

0.01

4b

.d.l

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Roberts Victor eclogites: A metasomatic history 6941

low contents of incompatible elements preclude any directrelationships between Type II eclogites and presentMORB-like protoliths; both basalts and gabbros (freshand altered) have flat REE patterns more similar to theType I eclogites (Hofmann, 1988; Hart et al., 1999; Bachet al., 2001; Coogan et al., 2001; Holm, 2002).

However, positive REE slopes and subchondritic Zr/Hfratios in eclogite xenoliths from Siberia and the Slave Cra-ton have been compared to melts such as boninites (Jacoband Foley, 1999; Aulbach et al., 2007) generated in aback-arc setting from the melting of a depleted mantle.Although the origins of Roberts Victor Type II are notthe subject of this study, we note that the LREE depletionof the Type II eclogites is beyond the spectrum describedfor the Siberian and Canadian eclogites, and the compari-son is probably not straightforward. However, it seems in-deed undeniable that such depletion must be generated in astrongly depleted mantle, which is not incompatible withthe refractory nature of the SCLM. It also is importantto recognise that markedly depleted LREE patterns as wellas chondritic to subchondritic Zr/Hf have been observed ingarnet pyroxenites from Pyrennean peridotite massifs andthe Beni Boussera massif and have been attributed to min-eral-liquid segregation during the migration of mafic mag-mas (Loubet and Allegre, 1982; Bodinier et al., 1987).

Type I eclogites have higher contents of incompatibleelements and present flatter patterns, which can be seenas suggesting affinities with a MORB-like protolith (e.g.Jacob et al., 2003). Nevertheless, some discrepancies persistand the differences between Type I and Type II patternsactually reside mostly in the lower concentrations of LREE,HFSE, K, Ba, Sr, Rb, Cs and Th in Type II eclogites(Fig. 7). These elements are typically enriched in metaso-matic fluid/melts and commonly are used as tracers ofmetasomatic enrichment processes. Therefore, it is possibleto envisage a metasomatic process linking Type II and TypeI eclogites.

In order to calculate the nature of the last fluid/melt inequilibrium with the Type I eclogites, we have used severalsets of garnet/melt partition coefficients established experi-mentally for hydrous basaltic melts (Green et al., 2000;6 GPa and 1200 �C), carbonated peridotites (Brey et al.,2008; 10 GPa and 1700 �C) and carbonatites (Dasguptaet al., 2009; 6.6 GPa and 1285 �C).. The calculated fluidsin equilibrium with Type I garnets (Electronic appendix2) show very steep trace-element patterns with markedenrichment in highly incompatible elements (Fig. 8a). Inde-pendently of the set used, the calculated fluids are, in termsof patterns and concentrations, very similar to a variety oflow-volume mantle-derived melts/fluids including carbona-tites or kimberlites. Such patterns cannot be ascribed to there-equilibration of the garnets with the ascending host mag-ma, simply because this feature is not observed in Type IIgarnets, which have been transported in the same magma.Mass-balance calculations between reconstructed and ana-lysed whole-rocks show that both eclogite types have re-acted with the same host magma. Moreover, only theType I eclogites show microstructural evidence of recent,metasomatism-related recrystallisation, while both typescontain spongy cpx, which reflects adiabatic melting during

Table 6Summary of typical petrographic and geochemical differences between Type II and Type I eclogites from Roberts Victor.

Type II eclogites Type I eclogites

Common garnet exsolutions in Cpx No Gt exsolutionsAnomalous rutile exsolutions in both Gt and Cpx No rutile exsolutionsPlanar fabric defined by garnet alignment and elongation Highly curvilinear grain boundariesNo primary phlogopite Primary phlogopite in some samplesClear Gt and Cpx “Dusty” aspect of GtNo Ni–Cu–Fe sulphides Abundant Ni–Cu–Fe sulphidesDiamonds never described Diamonds always described associated to Type I eclogitesNo “melt pockets” Abundant “melt pockets” in Gt

Na2OGt <0.07 wt% Na2OGt >0.07 wt%K2OCpx <0.08 wt% K2OCpx >0.08 wt%(FeO + CaO)Gt 21.9–31.2 wt% (FeO + CaO)Gt 16.6–23.7 wt%

avg. 26.5 wt% avg. 21.3 wt%Mg#Gt avg. 0.53 Mg#Gt avg. 0.63

Lower REE, HFSE and LILE contents than Type I eclogites Higher REE, HFSE and LILE contents than Type IIeclogites

Examples

NdCpx avg. 0.3 ppm NdCpx avg. 6 ppmSrCpx avg. 27 ppm SrCpx avg. 247 ppmZrCpx avg. 6 ppm ZrCpx avg. 22 ppmHfCpx avg. 0.5 ppm HfCpx avg. 1.3 ppmTiCpx avg. 1164 ppm TiCpx avg. 1970 ppm

Upward convex chondrite-normalised Cpx REE patterns with subchondritic

LREEUpward convex chondrite-normalised Cpx REE patternswith suprachondritic LREE

No positive SrN anomaly in Cpx Positive SrN anomaly in Cpx

CuCpx avg. 41.3 ppm CuCpx avg. 10.8 ppmZr/HfWR avg. 12.6 Zr/HfWR avg. 27.5(Nd/Lu)N-WR avg. 0.1 (Nd/Lu)N-WR avg. 2.0

6942 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

their journey to the surface; these observations imply thatthe metasomatic geochemical features of Type I have beenacquired before their entrainment in the kimberlite. Thiscombination of observations strongly suggests that theequilibration of Type I garnets with a small-volume meltoccurred prior to the eruption of the kimberlite.

Although the calculated melts/fluids are similar to someof the most commonly described metasomatic agents in thelithospheric mantle, it must be asked whether this melt/fluidcould be responsible for the transformation of the depletedeclogites (Type II) into metasomatised eclogites (Type I). Inorder to answer this question, a simple empirical and morequalitative approach has been adopted. The Type-I trace-element concentrations have been divided by the averagecomposition of Type II eclogites, to estimate what wouldneed to be added to Type II eclogites in order to producea Type-I composition (“normalisation to Type II”). Thetrace-element patterns produced using this method arestrikingly similar to the melts/fluids calculated from Type-I garnets (Fig. 8b). The main difference is a strong La–Ce–Pr anomaly in the “addition” pattern; this is most likelyan artefact, because La, Ce and Pr in Type II are extremelyclose to their detection limits. It seems unlikely that such asimilarity is coincidental; it is more likely that it reflects aprocess linking Type II eclogites to Type I.

This conclusion is supported by the observation that inone sample (HRV77) these two chemical signatures coexist

at the centimetre scale (Fig. 9). As described above, HRV77displays a composite structure, with one part (HRV77bimin)showing a typical Type I microstructure and mineral assem-blage (phlogopite patches, sulphides, melt pockets in gar-net) and the other (HRV77macrocx) consisting of aclinopyroxene macrocryst associated with clear (non-dusty)ovoid garnets, reminiscent of the Type II microstructure.The macrocrystic part of the sample has notably low con-centrations of incompatible elements, and a trace-elementpatterns similar to those of Type II eclogites, whereas thematrix is chemically a typical Type I eclogite. The conjunc-tion of these two chemical signatures, in a sample showing aprogressive loss of the Type II garnet microstructure in fa-vour of a Type I microstructure, strongly suggests that thechemical variations and the recrystallisation are linkedthrough the medium of a metasomatic fluid (Fig. 9).

Similar trace-element variations have been observed in adiamond-bearing eclogite from Udachnaya (Udachnaya;Ireland et al., 1994), where clinopyroxene inclusions in dia-monds and clinopyroxene from the host eclogite have strik-ingly different REE patterns (Fig. 10). These differenceswere attributed to a metasomatic event that affected thehost eclogite but not the inclusions shielded in the dia-monds. The authors proposed that a likely candidate forthe metasomatic agent is a kimberlite melt, similar to thecalculated fluid in equilibrium with our Type I eclogites.Fig. 10 shows that the cpx of the diamondiferous

Roberts Victor eclogites: A metasomatic history 6943

Udachnaya eclogite and the cpx of HRV77bimin have verysimilar trace-element patterns, as do the diamond-inclusioncpx and HRV77macrocx. The two latter patterns lie midwaybetween the pattern of the typical Type II cpx and theType-I cpx of HRV77bimin, consistent with the interpreta-tion that HRV77 records a transition between Type IIand Type I eclogites. Therefore, we propose that Type Itrace-element patterns reflect a metasomatic “refertilisa-tion” of the depleted Type II eclogites.

Although it is likely that such a trace-element refertilisa-tion occurred, the wide variations in major-element compo-sitions observed for Type I, especially in terms of MgO(10.1–16.7 wt%; D = 6.6 wt%), might seem more difficultto explain by metasomatism/melt percolation processes.However, recent studies of mantle refertilisation haveshown that such processes affect not only trace elementsbut also major elements. For example, in the Udachnayasamples described by Ireland et al. (1994), the minerals ofthe host eclogite have higher Mg# than the inclusionsshielded in diamonds, indicating that the metasomatismwas accompanied by addition of Mg.

Such refertilisation is now recognised as a significantprocess, capable of strongly modifying the major-elementcomposition of large volumes of the SCLM. In one specta-cular example, Le Roux et al. (2007) have shown that thelherzolites of the type locality (Lherz massif, France) aresecondary rocks, produced by melt-related metasomatismof a refractory harzburgite protolith. This process producedextreme differences (up to 10.6 wt%) in MgO content be-tween the most refractory harzburgites and the refertilisedlherzolites. The major-element variations observed in TypeI eclogites are compatible with such a refertilisationprocess.

Some of our samples, such as RV07-17, show large vari-ations in major-element composition at the thin-sectionscale; the MgO contents of garnet vary from 13.1 to15.3 wt%. Finally, we have observed correlations betweenmajor-element variations and indices of metasomatism,such as the broad correlation between MgOWR

* andRLREEcpx (Fig. 11) in which phlogopite-rich eclogites rep-resent some of the most enriched (metasomatised) samples.However, such trends are not necessarily very well definedbecause of the probably heterogenous nature of both theprotoliths and the metasomatic fluids, and the probablepre-existing variations in the physical properties of theeclogites that would affect the course of metasomatism(e.g. grain size, porosity, variations in chemicalcomposition).

7.2. Re-evaluation of evidence

With the light shed by the trace-element variations, a re-examination of the different lines of evidence previouslyused to support a subduction origin for the Roberts Victor(and possibly other) eclogites is necessary.

7.2.1. Evidence from petrography

Type II eclogites are characterised by clear “non-dusty”

garnets and cpx devoid of fluid inclusions. Their micro-structures are mostly planar, marked by the alignment of

elongated/ovoid garnets. No “primary” phlogopite, sulp-hides or melt blebs are observed. On the other hand, TypeI eclogites are characterised by “dusty” garnets rich in fluidinclusions. Their microstructures are more chaotic thanthose from Type II. Garnets display irregular boundariesand commonly are clustered. Transitions between ovoid“non-dusty” garnets and “dusty” irregular and clusteredgarnets are observed in samples HRV77 and RV07-17.We interpret these differences as reflecting the recrystallisa-tion of Type I eclogites in the presence of a fluid, now ob-served as dusty inclusions in the garnets.

Other evidence of recent recrystallisation includes theobservation of garnet and cpx enclosing each other, butwith multiple cpx inclusions in a garnet showing the sameoptical orientation under crossed nicols. In Type I eclogites,phlogopite and sulphides occur as inclusions in the rims ofgarnet and cpx grains, and melt blebs are almost alwayspresent in the garnets. Basically, Type II eclogites do notshow any evidence of metasomatism, whereas Type I eclog-ites show strong evidence for such a process (recrystallisa-tion, phlogopite, sulphides, melt blebs). Correlationsbetween sulphide abundances and indices of metasomatismare also observable in this dataset (Greau, 2011).

The obvious conclusion to be drawn from these observa-tions is that the Type I eclogites are not primary rocks, butstrongly modified metasomatites; they therefore carry little,if any, evidence for (or against) a subduction origin of theRoberts Victor eclogite suite.

7.2.2. Oxygen isotopes

Oxygen isotope data constitute one of the strongestarguments in favour of a subduction origin of mantle eclog-ites (e.g. Jagoutz et al., 1984; Macgregor and Manton, 1986;Jacob et al., 1994; Jacob and Foley, 1999; Jacob, 2004;Viljoen et al., 2005). Most suites of eclogite xenoliths fromkimberlites show wide variations in mineral d18O values(2–8&), which are both below and above the expected man-tle range (5.5 ± 0.4&; Mattey et al., 1994). These wide vari-ations are within the range observed in hydrothermallyaltered oceanic crust from ophiolite massifs (3–13&). Inthe Roberts Victor eclogites and numerous other mantleeclogite suites, the distribution of the d18O values is bimo-dal, with one population centred on 3& and the other on6& (Macgregor and Manton, 1986; Ongley et al., 1987;Caporuscio, 1990; Schulze et al., 2000; Jacob et al., 2005).This has been interpreted as reflecting hydrothermal alter-ation of different portions of the oceanic lithosphere atvarying temperatures (Macgregor and Manton, 1986), asobserved in ophiolites (Gregory and Taylor, 1981).

These two distinct populations correspond to the twotypes of eclogite described above. Type II eclogites corre-spond to the less positive d18O values and Type I eclogitescorrespond to the peak of d18O values centred on 6&. It isdifficult to explain the existence in the mantle of a low-d18Oreservoir such as the Type II eclogites. However, d18O val-ues more positive than the mantle average are common(especially in alkali magmas). The highest values are re-ported from carbonatites (Deines, 1989); the d18O of car-bonatites worldwide ranges from 4.5& to >25&

(Fig. 12a; Deines, 1989). Although many of these

Table 7Trace-element compositions of reconstructed whole-rocks.

Sample RV07-1

RV07-2

RV07-3

RV07-7

RV07-11

RV07-13

RV07-14

RV07-16

RV07-17

RV07-18

RV07-19

RV07-20

RV07-22

RV07-24

RV07-29a

RV07-29b

RV07-40

RV07-41

Type I I I I I I I I I I I I I I I I I IModes(%)

Garnet 42 28 62 55 53 42 70 58 26 67 68 55 48 54 65 44 54 25

cpx 58 73 38 45 47 58 30 42 74 33 32 45 52 46 35 56 46 75

Element

MgO wt% 13.20 12.79 12.88 13.61 13.86 12.90 14.29 11.46 11.73 14.25 12.80 14.77 13.70 11.98 14.22 13.29 16.68 14.39

Li ppm 5.30 8.52 1.90 4.48 4.90 5.16 4.17 9.53 7.47 4.55 6.19 1.89 6.62 5.44 3.87 5.22 0.96 5.49P ppm 84.4 65.8 94.5 97.5 127 95.2 156 162 75.8 109 152 84.2 99.3 115 90.4 82.5 303 64.5K ppm n.c. 957 n.c. n.c. n.c. 635 436 n.c. 1127 n.c. n.c. 456 569 419 482 755 n.c. n.c.Ti ppm n.c. 2072 2832 n.c. 1626 2146 1608 n.c. 2172 n.c. n.c. 1458 2030 1624 2105 1986 2556 1424Cr ppm n.c. 940 n.c. n.c. 649 784 977 n.c. 1126 n.c. n.c. 317 596 544 544 955 396 1220Ni ppm 208 218 82.6 155 109 118 120 181 207 146 147 80.9 200 217 140 192 197 256Cu ppm n.c. 6.88 n.c. n.c. 4.18 9.03 3.62 n.c. 4.74 n.c. n.c. 1.55 11.2 5.97 7.05 10.6 2.70 8.61Zn ppm n.c. 73.0 n.c. n.c. 68.2 77.1 67.5 n.c. 76.5 n.c. n.c. 43.7 70.0 67.6 53.4 51.6 44.7 74.2As ppm n.c. 3.24 n.c. n.c. 0.275 n.c. n.c. n.c. n.c. n.c. n.c. n.c. 0.139 n.c. n.c. 0.468 n.c. 0.299Rb ppm n.c. 1.07 0.13 0.03 n.c. 0.045 0.88 0.07 n.c. 0.07 0.08 n.c. n.c. n.c. n.c. 0.088 0.201 n.c.Sr ppm 149 170 125 102 111 146 68.4 54.7 156 70.2 46.9 115 118 56.5 92.5 154 184 257Y ppm 7.17 7.99 21.3 7.15 6.78 12.6 10.5 8.60 7.75 13.5 8.37 14.9 8.05 5.3 9.38 7.14 18.6 5.20Zr ppm 16.8 20.0 53.2 10.8 11.6 31.1 15.8 14.2 27.5 17.4 14.8 17.7 17.2 18.6 18.7 18.2 62.1 15.9Nb ppm n.c. 0.144 0.054 0.025 n.c. 0.032 0.039 0.041 0.031 0.034 0.026 0.041 0.029 n.c. 0.023 0.039 0.345 n.c.Cs ppm n.c. 0.508 n.c. n.c. n.c. n.c. 0.062 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Ba ppm n.c. n.c. 0.524 0.401 n.c. 0.320 1.44 0.182 0.399 0.318 0.298 0.555 0.730 0.651 n.c. 0.804 1.36 0.552La ppm 0.721 0.984 1.22 0.478 n.c. 0.809 0.351 0.178 0.961 0.335 0.191 1.18 0.529 n.c. 0.392 0.643 n.c. 1.36Ce ppm 3.05 4.62 4.46 2.06 2.20 3.64 1.41 0.849 3.76 1.37 0.900 4.82 2.24 0.893 1.70 2.75 5.79 5.41Pr ppm 0.571 0.780 0.846 0.388 0.402 0.735 0.269 0.182 0.645 0.284 0.192 0.779 0.461 0.212 0.372 0.562 1.49 1.01Nd ppm 3.16 3.98 5.09 2.23 2.23 3.93 1.65 1.33 3.32 1.68 1.35 4.08 2.61 1.50 2.25 3.10 9.09 5.32Sm ppm n.c. 1.04 1.61 n.c. 0.692 1.09 0.743 n.c. 0.940 n.c. n.c. 0.444 0.778 0.801 0.839 0.980 2.64 1.18Eu ppm 0.339 0.343 0.629 0.315 0.279 0.439 0.342 0.413 0.347 0.344 0.368 0.438 0.299 0.391 0.360 0.344 0.989 0.470Gd ppm n.c. 1.02 2.04 n.c. 0.770 1.42 1.10 n.c. 0.894 n.c. n.c. 1.38 0.930 0.983 1.08 1.02 3.00 1.03Tb ppm n.c. 0.185 n.c. n.c. 0.158 0.259 0.244 n.c. 0.177 n.c. n.c. 0.299 0.175 0.167 0.211 0.183 0.505 0.149Dy ppm 1.25 1.33 3.49 1.27 1.13 2.06 1.83 1.76 1.30 2.19 1.62 2.30 1.32 1.10 1.64 1.33 3.45 0.953Ho ppm 0.293 0.322 0.898 0.294 0.268 0.474 0.443 0.350 0.312 0.579 0.329 0.576 0.307 0.211 0.367 0.288 0.735 0.200Er ppm 0.875 0.991 3.02 0.830 0.810 1.48 1.34 0.806 0.936 1.67 0.912 1.87 0.933 0.751 1.06 0.805 1.85 0.594Tm ppm n.c. 0.161 n.c. n.c. 0.125 0.219 0.209 n.c. 0.157 n.c. n.c. 0.300 0.142 0.099 0.150 n.c. 0.242 0.096Yb ppm n.c. 1.19 4.04 n.c. 1.01 1.64 1.58 n.c. 1.14 n.c. n.c. 2.53 1.02 0.578 n.c. n.c. 1.42 0.714Lu ppm n.c. 0.184 0.647 0.130 0.157 0.246 0.248 n.c. 0.180 0.272 n.c. 0.395 0.152 0.110 0.152 0.139 0.172 0.103Hf ppm 0.659 1.03 1.89 0.394 0.413 1.86 0.536 0.379 1.35 0.550 0.432 0.496 0.644 0.568 0.628 0.748 2.00 0.763Ta ppm n.c. n.c. 0.014 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Pb ppm 0.252 0.775 0.307 0.255 0.242 n.c. 0.264 0.147 n.c. 0.877 0.113 1.443 0.252 n.c. 0.199 n.c. n.c. n.c.Th ppm 0.014 n.c. 0.018 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.U ppm 0.012 0.392 n.c. n.c. n.c. n.c. n.c. 0.019 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.

(continued on next page)

6944Y

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Table 7 (continued)

Sample XRV6dusty XRV6clean HRV77bimin RV07-9a

RV07-9b

RV73-12

RV07-8

RV07-12

RV07-30

RV07-31

RV07-33

RV07-34

RV07-36

RV07-37

RV07-66

HRV77macrocx

Type I I I I I II II II II II II II II II II IIModes (%) Garnet 74 74 25 25 30 45 40 50 41 55 40 31 55 58 77 5

cpx 26 26 65 53 58 55 60 51 60 45 60 69 45 42 23 95

Element

MgO wt% 12.52 11.06 11.13 15.01 13.93 12.39 8.37 11.33 10.24 9.93 9.13 7.59 13.40 10.95 14.53 10.09

Li ppm 2.38 1.76 5.65 3.65 3.62 5.88 6.43 5.61 9.16 6.18 6.59 7.19 4.48 5.46 0.87 13.9P ppm 103 89.5 68.0 57.7 89.6 25.1 8.6 41.3 13.5 33.1 20.8 25.0 55.6 46.9 33.7 19.6K ppm 397 273 619 n.c. 548 15.5 n.c. 4.27 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Ti ppm 2218 1896 1722 1330 1476 1059 1245 939 870 873 953 1269 765 1212 741 1870Cr ppm 496 491 953 1147 603 1564 n.c. 792 533 377 199 207 660 454 1310 1459Ni ppm 76 77 169 128 225 356 97 354 362 192 186 125 407 209 223 343Cu ppm 2.83 2.83 5.42 2.89 2.46 29.8 25.0 28.4 20.4 19.1 24.6 59.0 24.3 19.0 0.93 22.0Zn ppm 68.8 70.1 50.0 59.5 89.9 108.1 n.c. 102.1 89.0 87.9 79.5 60.9 104.8 81.5 50.0 83.6As ppm 0.35 0.234 n.c. 0.145 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Rb ppm 0.45 0.051 n.c. n.c. n.c. n.c. 0.09 n.c. n.c. 0.02 n.c. n.c. n.c. n.c. n.c. n.c.Sr ppm 73.3 71.5 135 167 179 14.2 6.61 34.3 9.09 9.48 11.3 7.33 41.3 6.88 2.86 194Y ppm 17.1 19.3 6.2 7.60 10.8 19.5 23.348 22.9 11.4 15.2 10.0 9.3 26.8 19.4 20.1 1.6Zr ppm 28.0 29.2 14.9 25.8 27.7 3.91 1.678 11.4 2.4 1.2 0.5 0.8 7.48 4.80 2.3 11.6Nb ppm 0.167 n.c. n.c. n.c. 0.046 0.025 n.c. 0.017 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Cs ppm n.c. n.c. n.c. 0.010 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Ba ppm 8.10 n.c. 0.436 n.c. n.c. 0.279 n.c. n.c. 0.159 n.c. n.c. n.c. n.c. n.c. n.c. n.c.La ppm 0.834 0.561 n.c. 1.53 1.78 0.045 n.c. n.c. n.c. n.c. n.c. 0.012 n.c. n.c. n.c. n.c.Ce ppm 3.22 2.76 3.22 6.41 7.08 0.075 n.c. 0.249 0.030 n.c. n.c. n.c. n.c. n.c. n.c. 0.616Pr ppm 0.556 0.558 0.611 1.09 1.18 n.c. 0.011 0.161 n.c. n.c. n.c. 0.009 n.c. n.c. n.c. 0.207Nd ppm 3.33 3.59 3.12 5.62 5.86 0.258 0.153 1.93 n.c. 0.122 0.099 0.106 n.c. 0.189 0.130 1.531Sm ppm 1.24 1.49 0.845 1.16 1.33 0.411 0.289 1.56 0.265 0.337 0.239 0.187 1.35 0.371 0.200 0.622Eu ppm 0.563 0.759 0.299 0.382 0.484 0.291 0.223 0.733 0.212 0.321 0.199 0.150 0.677 0.325 0.186 0.255Gd ppm 1.80 2.50 0.853 1.02 1.48 1.35 1.14 2.80 0.785 1.135 0.738 0.588 2.58 1.29 0.937 0.505Tb ppm 0.388 0.483 0.141 0.177 0.281 0.322 n.c. 0.539 0.219 0.296 0.191 0.161 0.551 0.346 0.306 0.072Dy ppm 2.76 3.42 0.972 1.27 1.91 2.84 3.16 3.97 1.75 2.41 1.62 1.36 4.30 2.94 2.66 0.366Ho ppm 0.649 0.748 0.241 0.309 0.428 0.714 0.918 0.869 0.447 0.622 0.400 0.361 1.046 0.743 0.782 0.066Er ppm 1.93 2.11 0.844 0.970 1.217 2.39 3.13 2.42 1.42 1.89 1.26 1.17 3.14 2.35 2.46 0.232Tm ppm 0.302 0.326 0.124 0.154 0.181 0.367 n.c. 0.356 0.227 n.c. 0.194 0.184 0.477 n.c. 0.423 n.c.Yb ppm 2.24 2.44 0.973 1.25 1.30 2.78 4.24 2.53 1.77 2.35 1.50 1.45 3.43 n.c. 3.28 n.c.Lu ppm 0.323 0.336 n.c. 0.199 0.188 0.441 0.655 0.363 n.c. 0.341 0.208 0.219 n.c. n.c. 0.508 n.c.Hf ppm 0.816 0.825 0.763 1.31 1.17 0.375 0.175 0.775 0.192 0.112 0.081 0.121 0.461 0.303 0.120 0.701Ta ppm 0.015 n.c. n.c. 0.007 0.021 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.Pb ppm 0.282 0.166 n.c. 0.488 0.509 0.032 0.047 n.c. 0.118 0.148 0.054 n.c. n.c. n.c. n.c. n.c.Th ppm n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.U ppm 0.014 0.012 n.c. 0.025 n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c. n.c.

n.c. = not calculable.Modes were derived from whole-rock major element contents and individual mineral analyses or from visual estimation when the sample size did not allow whole-rock analysis.

Ro

berts

Victo

reclo

gites:A

metaso

matic

histo

ry6945

0.001

0.01

0.1

1

10

100

K Cs Rb Ba Th U La Ce Pb Pr Nd Sr Sm Eu Ti Gd Dy Ho Y Yb Lu Zr Hf Nb Ta

Rec

on

stru

cted

wh

ole

-ro

ck/C

I ch

on

dri

tes

Metasomatic refertilisationAverage Type IAverage Type IIN-MORBOceanic gabbrosBoninite-like melts

Fig. 7. Extended trace-element patterns of average reconstructed Type I and Type II whole-rocks compared to N-MORB (Hofmann, 1988),oceanic gabbros (compiled from Hart et al., 1999; Bach et al., 2001; Coogan et al., 2001; Holm, 2002) and boninite-like melts (Polat et al.,2002). Grey arrows show the proposed metasomatic relationship between Type II and Type I eclogites. Normalised to CI chondrite values ofAnders and Grevesse (1989).

6946 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

carbonatites may have undergone some crustal contamina-tion, most of the data still lie in an array compatible withmantle-like signatures in terms of d13C (�3 to �7&;Fig. 12a; Deines, 1989) and therefore indicate little or nocontamination. From this, it seems reasonable to proposethat the d18O of carbonatites ranging from 5.5& to10.5& (Fig. 12a) are a good estimation of the d18O compo-sitions of carbonatites in the mantle. This suggests that theinteraction of such an isotopically heavy component withthe Type-II eclogites, involving reactions and recrystallisa-tion at high fluid/rock ratios, could give intermediate valuesof d18O (Fig. 12a) such as those observed in Type I eclogites(Ongley et al., 1987). This seems to be in accordance withthe calculated d18O values (Fig. 12b; Zheng, 1993) of thehydrated (6.1–9.1&) or carbonic fluids (5.5–8.5&) in equi-librium with Type I garnets. Estimations of fluid/rock ra-tios needed to shift the d18O values from 3& to 6& (in aclosed system) range from 2& to 25% depending on thenature of the fluid (hydrated or carbonic) and its d18O com-position. This is in accordance with simple mass-balancecalculations based on the concentrations of incompatibletrace elements, which indicate that 3–19% of fluid is neededto refertilise the Type II eclogites to the levels observed inType I.

Similar high d18O values (6–7&) are also found in someperidotite xenoliths from kimberlites (Kyser et al., 1981,1982; Gregory and Taylor, 1986; Zhang et al., 2000; Tayloret al., 2005). While most of these studies proposed thatthese isotopic compositions were the result of metasomaticprocesses, Taylor et al. (2005) attributed them to seawateralteration of shallow peridotitic bodies within the oceaniccrust. This interpretation involved a bit of circular reason-ing as it is strongly based on the assumption that the asso-ciated eclogites have a subduction-related origin. However,the subduction hypothesis was itself mostly supported by

the apparent absence of d18O variations in peridotite sam-ples (e.g. Mattey et al., 1994). Moreover, no examples oflow d18O (ca 3&) in peridotite xenoliths have been re-ported, while the mechanism proposed by Taylor et al.(2005) would be expected to generate some peridotites withlow d18O as well.

Recently, new light has been shed on stable-isotope frac-tionation during mantle processes. Developments in theanalysis of Fe isotopes have resulted in several studies thatexplain significant d57Fe variations, preserved in mantleperidotites and pyroxenites, as being the result of meltextraction, melt percolation and metasomatism (Williamset al., 2004, 2005; Weyer and Ionov, 2007). More impor-tantly, Williams et al. (2009) showed positive correlationsbetween d57Fe and d18O (grt and cpx) in a suite of SouthAfrican eclogite xenoliths (two Type I, four Type II; allwith LREE-enriched trace-element patterns). However, nod57Fe fractionation and no correlations between d57Feand d18O were observed in a suite of altered oceanic basalticdykes, and the authors concluded that the isotopic compo-sitions of Fe and O in their eclogites cannot be directlyinherited from an altered crustal protolith but must reflecta secondary process in the mantle.

Williams et al. (2009) argued against metasomatism as acause of isotopic fractionation because there were no re-ported correlations between d57Fe or d18O and metasomaticindices such as LREE. However, the d18O values of garnetfrom the Roberts Victor samples studied here show positivecorrelations with several different indices relevant to themetasomatism described in this study. d18O of garnet is pos-itively correlated with [La] in cpx, [Hf] and [Zr] in garnet,and [Ce], [Zr], and [Sr] of the reconstructed whole-rocks(Fig. 13). d18O also correlates positively with whole-rock[Se] and the modal abundance of sulphides (Greau, 2011).On most of these plots the phlogopite-rich eclogite is the

0.1

1

10

100

1000

10000

Ba La Ce Pr Nd Sr Sm Eu Gd Tb Dy Ho Y Er YbLu Zr Hf Nb Ta0.01

0.01Ba La Ce Pr Nd SrSm EuGd Tb Dy Ho Y Er Yb Lu Zr Hf Nb Ta

a

b

Liqu

id/C

I cho

ndrit

es

Type

I/Av

erag

e Ty

pe II

Liqu

id/C

I cho

ndrit

es

Caculated fluid/melt in equilibrium with Type I garnets using Ds for:

Small-volume mantle melts :Average carbonatite Silicate melt in cpxmegacryst (Araujo et al., 2009)Calcite-silicate melt in cpxmegacryst (Araujo et al., 2009)Fibrous diamonds (Rege, 2005)

Carbonatitic melt at 6.6 GPa and 1285ºC (Dasgupta et al., 2009)Carbonated peridotite melt at 10 GPa and 1700ºC (Brey et al., 2008)Hydrous basaltic melt at 6 GPa and 1200ºC (Green et al., 2000)

0.1

1

10

100

1000

10000

Liquids in equilibrium withType I garnets

Fluid/melt neededto transform II into I

Fig. 8. Extended trace-element pattern showing the compositional range of calculated fluids in equilibrium with Type I garnets, usingpartition coefficients for garnet/silicate melt (Green et al., 2000), garnet/carbonatitic melt (Dasgupta et al., 2009) and garnet/carbonatedperidotite melt (Brey et al., 2008). (a) Compared to worldwide average carbonatite compositions (Nelson et al., 1988), fibrous diamondcomposition (circle; Rege, 2005), Calcite-silicate globules in cpx megacryst (triangle; Araujo et al., 2009), silicate melt in cpx megacryst(square; Araujo et al., 2009). (b) Compared to Type I samples normalised to the average Type II compositions (dark grey field) and silicatemelt in cpx megacryst (square; Araujo et al., 2009). Note that only fluids calculated using partition coefficients from Green et al. (2000) (lightgrey field) are shown in (b).

Roberts Victor eclogites: A metasomatic history 6947

most enriched sample. It is also noteworthy that d18O ofgarnet is negatively correlated with the Cu content of cpx,another strong discriminator between Type I and Type IIeclogites.

The study of Williams et al. (2009), and the correlationsbetween d18O and these metasomatism indices, thereforesupport the metasomatic refertilisation model proposedabove, in which Type I eclogites are the product of reactionbetween the Type II eclogites and a high-d18O fluid/meltsuch as carbonatite, kimberlite or related low-volume flu-ids/melts.

If such a fluid/melt interacted with the eclogites it wouldalso be expected to affect the surrounding peridotites. Asmentioned above, the few ultramafic xenoliths present atRoberts Victor are intensively altered to serpentine, calciteand quartz (Williams, 1932; Hatton, 1978; Viljoen et al.,1991), which may be attributed to metasomatism. However,the heavy-mineral concentrates from the kimberlite containabundant, unaltered harzburgitic to lherzolitic garnets. The

chemical fingerprint of metasomatism in Roberts Victorperidotitic garnets can be observed in the Y versus Zr plotfor these garnets (Fig. 14) (Griffin et al., 1999), indicatingthat peridotitic wall-rock may have been modified by thesame metasomatic agent(s). Although, this diagram hasbeen developed for peridotitic garnets, Roberts VictorType-I eclogitic garnets fall in the “depleted” field but showa trend extending toward the “melt metasomatism” field,and overlapping a population of similarly metasomatisedperidotitic garnets from Roberts Victor.

7.2.3. Eclogites and diamonds

Mantle eclogites are one of the two main host rocks ofdiamonds. However, it was early recognised that only TypeI eclogites carry diamonds and that Type II are barren;McCandless and Gurney (1989) proposed their classifica-tion as a tool for evaluation of the diamond potential ofexploration targets. Later work has shown that all reportedinclusions in eclogitic diamonds are of Type I affinity (high

cpx macrocryst(Type II)bimineralic

eclogite (Type I) contact

Sulfide

ovoid garnets

clusteredunequilibrated garnets

melt pockets

phlogopite

2 cm

Bimineralic part

Macrocryst

Contact

cpx/

cho

nd

rite

s

0.01

0.1

1

10

100

Macrocryst close to contact

Contact

cpx/

cho

nd

rite

s

Macrocryst

cpx/

cho

nd

rite

s

Macrocryst

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er

Macrocryst close to contact

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er

0.01

0.1

1

10

100

0.01

0.1

1

10

100

1

2

3

Type-II fieldType-I field

20

40

6080100

HRV77bimin

HRV77macrocx

Ca

Mg Fe

20

40

60

40garnets

Fig. 9. Sketch of the petrographic structure of composite xenolith HRV77 and the associated chemical variability. Note the progressive loss ofovoid shape and preferential orientation of garnet as moving away from the contact. Cpx boundaries are not represented in the bimineralicpart but grain-size is similar to garnet. Contact is composed of the macrocrystic cpx showing features of destabilisation. Bottom quadrilateralshows variations of major-element compositions between dusty garnets sitting in the bimineralic part (diamonds) and ovoid clear garnetssitting in the cpx macrocryst (circles). Right side REE patterns of cpx: (1) macrocrystic cpx; (2) macrocrystic cpx close to contact and contactitself; (3) cpx in the bimineralic part. Note the progressive enrichment in LREE from a Type II pattern to the typical Type I pattern.

met

asom

atis

m

0.1

1

10

100

Ba La Ce Pr Nd Sr Sm Eu Ti Gd Dy Ho Y Yb Lu Zr Hf

CPX

/CI c

hond

rites

Avg. Type II CPX

Ud146 CPX-DI (Ireland et al., 1994)Ud146 CPX-ROCK (Ireland et al., 1994)HRV77macrocx CPX

HRV77bimin CPX

Fig. 10. Trace-element patterns of both HRV77 cpx types (trian-gles) compared to cpx from diamondiferous eclogite (open circle)and associated cpx diamond inclusion (solid circle) from Uda-chnaya (Ireland et al., 1994), for which the differences in the trace-element patterns have been interpreted as the results of metaso-matism. The average trace-element pattern of Roberts Victor TypeII cpx is also shown for comparison.

HRV77biminHRV77macrocx

RV07-17

MgO WR* (wt%)

ΣLR

EE c

px (p

pm)

0.0

10.0

20.0

30.0

40.0

7.0 9.0 11.0 13.0 15.0 17.0

R2= 0.40

Fig. 11. RLREE content in cpx versus reconstructed whole-rock(WR*) MgO content. Triangles, phlogopite-bearing; squares, TypeI; circles, Type II.

6948 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11

a

b

T (ºC

)N

SA

MPL

ES

CarbonatitesType II EclogitesType I Eclogites

MIXING?

δ18O ‰ (V-SMOW)

δ18O ‰ (V-SMOW)

0 5 10 15 20 25 30

0

5

-5

-10

-15

δ18O ‰ (V-SMOW)

δ13 C

‰ (P

DB)

950

1000

1050

1100

1150

1200

1250

1300

Carbonatites

Type I

Type II

2 3 4 5 6 7 8 9 10 11

Type II garnet (this study)Type I garnet (this study)CO2-rich fluid in equilibrium H2O-rich fluid in equilibrium

1

Fig. 12. (a) Frequency diagram of d18O compositions of Type I eclogites, Type II eclogites and carbonatites. Carbonatite data from Deines(1989), eclogite data from Ongley et al. (1987), Caporuscio (1990), MacGregor and Manton (1986), Schulze et al. (2000), Jacob et al. (2005)and this study. Inset shows d13C vs. d18O of carbonatite worldwide (Deines, 1989) illustrating that most carbonatites with mantle-like d13C(�3 to �7&) have a d18O pristine of crustal contamination (5.5–10.5&). (b) Calculated d18O compositions of hydrated- or CO2-rich fluids inequilibrium with Roberts Victor garnets (this study). Parameters and method from Zheng (1993).

Roberts Victor eclogites: A metasomatic history 6949

Na in garnet and/or high K in cpx). Although this couplingbetween diamonds and Type I eclogites is well known, ourstudy can add another dimension. Most, if not all, RobertsVictor Type I eclogites carry sulphides whereas Type II arealways sulphide-free. This is pertinent because sulphides arethe most common inclusion in diamonds (Sharp, 1966;Sobolev, 1977; Harris, 1992; Sobolev et al., 1999a) and theyhave been linked to the genesis of diamond (Haggerty,1986; Shushkanova and Litvin, 2008).

Several recent studies based on in-situ analyses of fi-brous (“turbid”) diamonds have suggested that diamondscrystallise from a variety of metasomatic fluids (Weisset al., 2009; references therein). Although these range inmajor-element composition from carbonatite to hydro-silicic melts, and to highly saline brines, they have very

similar trace-element patterns. Araujo et al. (2009) de-scribed immiscibility between silicate and carbonatiticmelts trapped in Cr-diopside megacrysts derived from6 GPa (ca 180 km) beneath the Diavik kimberlite fieldof the Slave craton. These melts, ranging from Mg-silicate to Ca–Mg carbonate, have very similar trace-element patterns, which correspond to those of carbonat-itic to silicic fluids trapped in fibrous coats on diamondsfrom the Diavik kimberlites. The trace-element patternsof non-fibrous diamonds and clear outer rims on fibrousdiamonds show more complexity, suggesting the evolu-tion of fluids to different trace-element patterns; thereseems to be little difference between the fluids that depos-it diamonds in eclogitic and peridotitic matrices (Regeet al., 2010).

0

1

2

3

2 3 4 5 6 7

Type IType II

Type I phogopite

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1

2

3

4

5

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0.2

0.4

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[La]

cp

x p

pm

[Zr]

gt

pp

m[H

f] g

t p

pm

[Ce]

WR

* p

pm

[Zr]

WR

* p

pm

[Sr]

WR

* p

pm

δ18O gt (‰)

0

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10

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20

25

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2 3 4 5 6 7

a

b

c

d

e

f

δ18O gt (‰)

δ18O gt (‰) δ18O gt (‰)

δ18O gt (‰)

δ18O gt (‰)

Fig. 13. Correlations between d18O and trace elements commonly use as indices of metasomatism. Symbols same as Fig. 9.

Zr Garnet (ppm)

Y G

arn

et (

pp

m)

“Phlo

gopite”

met

asom

atis

m

0

20

40

60

0 50 100 150

Fertile

Melt-Metasomatism

Garnet concentrate RVType I eclogite

Fig. 14. Zr content versus Y content of peridotitic garnets (opentriangles) from Roberts Victor heavy-mineral concentrates (Griffinet al., 2003) indicating the chemical fingerprinting of the peridotiticwall-rock by metasomatism. Also shown are the Type I eclogiticgarnets (diamonds) from this study.

6950 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

As shown above (Fig. 8a) the calculated trace-elementpatterns of the metasomatic fluids with which Type I eclog-ites have equilibrated are very similar to the fluids found infibrous diamonds, and in the trapped melts described byAraujo et al. (2009). The trace-element data do not allowus to distinguish between carbonatites and other fluids ormelts in the spectrum produced during progressive low-volume melting of carbonated peridotite (Gudfinnssonand Presnall, 2005). However, the proposed massivemajor-element modification of the eclogitic whole-rocksand the presence of abundant sulphides, suggest that weare dealing with melts, carrying significant amounts ofimmiscible sulphide.

Therefore, we can define a trinity of “Type I silicates(metasomatised)-sulphide-diamond”. This trinity seems tobe ubiquitous in the Type I eclogites and strongly arguesfor a metasomatic process. It noteworthy that the classicmetasomatic mineral phlogopite is commonly found associ-ated with sulphides or carbonates in Roberts Victor eclog-ites, and is also found (though rarely) as inclusions indiamond (Sobolev et al., 2009). Such K-rich metasomatism

LAB

LAB

Type II eclogite

DiamondSulfide Phlogopite

PeridotiteType I eclogite Metasomatised peridotite

Percolating fluid/melt

a

0.001

0.01

0.1

1

10

100

PbK

CsRb

BaLa

CePr

NdSr

SmEu

GdDy

HoY

YbLu

TiZr

HfNb

TaTh

U

0.001

0.01

0.1

1

10

100

PbK

CsRb

BaLa

CePr

NdSr

SmEu

GdDy

HoY

YbLu

TiZr

HfNb

TaTh

U

WR Type II

WR Type I

b

Fig. 15. Schematic diagram illustrating the proposed mechanism responsible for the transformation of Type II eclogites onto Type I eclogites.(a) Eclogite body and peridotitic wall-rock prior metasomatism. On the right, summaries of typical microstructure and trace-elementcomposition of Type II eclogites. (b) Metasomatic event via percolation of melt/fluid through the eclogites body and the peridotitic wall-rock.Recrystallisation of the eclogitic assemblage and growing of phlogopite, diamond and sulphide. On the right, summaries of typicalmicrostructure and trace-element composition of Type I eclogites.

Roberts Victor eclogites: A metasomatic history 6951

also explain why Type I cpx are richer in K2O than com-pared to Type II cpx, even though the P–T estimates placethe two rock types at similar depths in the mantle.

8. SUMMARY AND CONCLUSIONS

The Roberts Victor eclogites can be divided into twomain groups following the McCandless and Gurney classi-fication (1989). This study shows that other petrographicand geochemical features can be used as criteria to completethis classification and to investigate the links between thetwo groups. Polyphase sulphides and melt pockets in gar-nets are only associated with Type I eclogites. High con-tents of incompatible elements (LREE, HFSE, LILE) aretypical of Type I eclogites, whereas low incompatible-element contents and high Cu contents in cpx (>20 ppm)are markers of Type II eclogites. Type II eclogites carry pet-rographic evidence of cooling from high T (exsolution ofrutile in cpx and gnt, exsolution of gnt from cpx); thesefeatures are absent in Type I eclogites.

We propose (Fig. 15) that the distinct geochemical signa-tures and petrographic features of the two groups can be rec-onciled by the percolation of low-volume fluids/melts in thecarbonatite–kimberlite spectrum through the primary TypeII eclogites. During this process, the metasomatic agent in-duced subsolidus recrystallisation of the silicates, obliterat-ing their primary fabric. The metasomatic agent alsointroduced sulphides + phlogopite ± diamond and left meltpockets trapped within the recrystallising garnets. The meta-somatism produced a marked enrichment in incompatibleelements (LREE, HFSE, Sr, Ba, K, Rb, Cs, U. . .) and chan-ged the major-element compositions of the eclogites to be-come more Mg-rich and less Fe- and Ca-rich. The presenceof micron-sized fluid inclusions, and recrystallisation in thepresence of the 18O-rich fluid/melt, shifted the low-d18O com-positions of Type II eclogites (mean �3.5&) towards thehigher Type I values (�6.5&) typical of Type I eclogites.

Microstructural features such as melt pockets andthe unequilibrated grain boundaries of Type I eclogitessuggest that this metasomatism occurred shortly before

6952 Y. Greau et al. / Geochimica et Cosmochimica Acta 75 (2011) 6927–6954

entrainment of the eclogite xenoliths in the Roberts Victorkimberlite.

Other stable isotopes (Mg, Fe) and radiogenic isotopes(Nd–Sr–Hf) are currently under investigation to further testthis model. Preliminary results confirm the existence of twoisotopically distinct reservoirs, representing the Type IIeclogites and the metasomatic fluid, and the young age ofmetasomatic features in the Type I eclogites (Huanget al., 2010).

The Roberts Victor Type I eclogites are the products ofhigh-degree metasomatism, and carry little “memory” oftheir original elemental or isotopic compositions; they can-not be used to determine the origin of this suite of eclogites.However, Type II eclogites may represent the protoliths ofthese rocks and are therefore the key samples for under-standing the ultimate origin of this eclogite suite.

ACKNOWLEDGEMENTS

We are grateful to John Gurney for providing complementarysamples, which helped refine our observations, and to Simon Shee,who facilitated the collecting expedition and provided other sam-ples. We also thank Norman Pearson and Alan Kobussen for theirhelp collecting samples. Generous technical assistance by PeterWieland in the use of the analytical instruments at GEMOC isgreatly appreciated; Dr. Pearson also assisted with helpful discus-sions on the interpretation and instrumental aspects. The paperbenefited greatly from the constructive reviews provided by theAssociate Editor, Peter Ulmer, and by Sonja Aulbach, MichelGregoire and an anonymous reviewer. This project was supportedby Macquarie University international postgraduate scholarshipsand ARC (Australian Research Council) Discovery and LinkageGrants (O’Reilly, Griffin). The study used instrumentation fundedby ARC LIEF and DEST Systemic Infrastructure Grants, Mac-quarie University and Industry. This is contribution #772 fromthe GEMOC ARC National Key Centre (www.gemoc.mq.edu.au)and #003 from the CCFS ARC Centre of Excellence(www.ccfs.mq.edu.au).

APPENDIX A. SUPPLEMENTARY DATA

Supplementary data associated with this article can befound, in the online version, at doi:10.1016/j.gca.2011.08.035.

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