Magmatic evolution, xenolith mineralogy, and emplacement history of the Aries micaceous ...

365 Pages·2013·24.23 MB·English

Magmatic evolution, xenolith mineralogy, and
emplacement history of the Aries micaceous
kimberlite, central Kimberley Basin, Western
Australia.

Peter Jason Downes
B.Sc. (Hons.), The University of Queensland

This Thesis is presented for the degree of Doctor of Philosophy at
The University of Western Australia

School of Earth and Geographical Sciences

Supervisors: Professor Brendan J. Griffin, Dr Neal McNaughton and
Associate Professor Alex W. R. Bevan (external)

Thesis Submitted: May, 2006.
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ABSTRACT
The Neoproterozoic (815.4 ± 4.3 Ma) Aries kimberlite intrudes the King Leopold
Sandstone and the Carson Volcanics in the central Kimberley Basin, northern Western
Australia. Aries is comprised of a N-NNE-trending series of three diatremes and
associated hypabyssal kimberlite dykes and plugs. The diatremes are volumetrically
dominated by massive, clast-supported, accidental lithic-rich kimberlite breccias that
were intruded by hypabyssal macrocrystic phlogopite kimberlite dykes and plugs with
variably uniform- to globular segregationary-textured groundmasses. Lower diatreme-
facies, accidental lithic-rich breccias probably formed through fall-back of debris into
the vent with a major contribution from the collapse of the vent walls. These massive
breccias are overlain by a sequence of bedded volcaniclastic breccias in the upper part
of the north lobe diatreme. Abundant, poorly-vesicular to nonvesicular, juvenile
kimberlite ash and lapilli, with morphologies that are indicative of phreatomagmatic
fragmentation processes, occur in a reversely-graded volcaniclastic kimberlite breccia
unit at the base of this sequence. This unit and overlying bedded accidental lithic-rich
breccias are interpreted to be sediment gravity-flow deposits (including possible debris
flows) derived from the collapse of the crater walls and/or tephra ring deposits that
surrounded the crater. Diatreme-forming eruptions may have been initiated by magma-
water interactions along fracture and joint-controlled aquifers within the King Leopold
Sandstone. The current level of exposure of the diatremes probably extends from the
lower-diatreme facies, up into the base of a bedded upper-diatreme sequence.

Hypabyssal macrocrystic phlogopite kimberlite dykes exhibit differentiation to a
minor high-Na, Si olivine-phlogopite-richterite kimberlite, and late-stage, narrow
macrocrystic serpentine-diopside ultramafic dykes in the north extension lobe.
Chemical zonation of phlogopite-biotite phenocrysts indicates a complex magmatic
history for the Aries kimberlite, with the early inheritance of a range of high-Ti
phlogopite-biotite macrocrysts from metasomatised mantle lithologies, followed by the
crystallisation of a population of high-Cr phlogopite phenocrysts (containing up to 1.7
wt% Cr O at Mg numbers of 83-90 (increasing with Cr O content) and ~1.2-1.9 wt%
2 3 2 3
TiO ) within the spinel facies lithospheric mantle. It is inferred that this range in the
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Cr O content of phlogopite phenocrysts was controlled by variations in magma
2 3
chemistry produced by the assimilation of mantle peridotite. The crystallisation of one
to two further overgrowth rims of phlogopite occurred at higher levels and upon
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emplacement. Mineralogical and geochemical evidence suggest that the high-Na, Si
olivine-phlogopite-richterite kimberlite was derived from the macrocrystic phlogopite
kimberlite as a residual liquid following extended phlogopite crystallisation and the
assimilation of country rock sandstone, and that macrocrystic serpentine-diopside
ultramafic dykes formed as mafic cumulates from macrocrystic phlogopite kimberlite.

Ultra-violet laser 40Ar/39Ar dating of phlogopite grain rims yielded a kimberlite
eruption age of 815.4 ± 4.3 Ma (95% confidence). 40Ar/39Ar laser profiling of one high-
Ti phlogopite-biotite macrocryst revealed a radiogenic 40Ar diffusive loss profile, from
which a kimberlite magma ascent duration from the spinel facies lithospheric mantle
was estimated (assuming an average kimberlite magma temperature of 1000˚C),
yielding values of ca 0.23-2.32 days for the north extension lobe of the Aries
kimberlite. This high-Ti phlogopite-biotite macrocryst produced a maximum 40Ar/39Ar
core age of 951.8 ± 7.9 Ma, which suggests that the central Kimberley block may have
been affected by a mantle metasomatic or another resetting event at ca 950 Ma.

The Aries kimberlite contains a suite of 27 serpentinised ultramafic xenoliths,
including aluminous to chromian spinel-bearing, and rare, metasomatised, phlogopite-
biotite and rutile-bearing types, along with minor granite xenoliths. Proton-probe trace-
element analysis of pyrope and chromian spinel grains derived from heavy mineral
concentrates from the kimberlite has been used to define a Proterozoic geotherm for the
central Kimberley Craton, of ~35-40 mW/m2. Lherzolitic chromian pyrope, that is
highly depleted in Zr and Y, and Cr-rich magnesiochromite xenocrysts (class 1),
probably were derived from depleted garnet peridotite mantle at ~150 km depth.
Sampling of shallower levels of the lithospheric mantle by kimberlite magmas in the
north and north extension lobes entrained high-Fe chromite xenocrysts (class 2), and
aluminous spinel-bearing xenoliths, where the compositions of both the aluminous
spinel and the chromite are anomalously Fe-rich for spinel-group minerals from mantle
xenoliths. This Fe-enrichment may have resulted from Fe-Mg exchange with olivine
during slow cooling of the peridotite host rocks. Textures reflecting the cooling history
of some mantle xenoliths are preserved in the form of fine exsolution rods of aluminous
spinel in diopside and zircon in rutile grains in aluminous spinel- and rutile-bearing
serpentinised ultramafic xenoliths, respectively. These textures suggest nearly isobaric
cooling of host rocks in the lithospheric mantle, and indicate that at least some
aluminous spinel in spinel-facies peridotites formed through exsolution from chromian
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diopside. Episodes of Fe-Ti-rich metasomatism in the spinel-facies Kimberley mantle
are the likely source of high-Ti phlogopite-biotite + rutile and Ti, V, Zn, Ni-enriched
aluminous spinel ± ilmenite associations in several ultramafic xenoliths. U-Pb SHRIMP
207Pb/206Pb zircon ages for one granite (1851 ± 10 Ma) and two serpentinised ultramafic
xenoliths (1845 ± 30 Ma; 1861 ± 31 Ma) indicate that the granitic basement and lower
crust beneath the central Kimberley Basin are at least Palaeoproterozoic in age.
However, Hf-isotope analyses of the zircons in the ultramafic xenoliths suggest that the
underlying lithospheric mantle is at least late Archaean in age.
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ACKNOWLEDGEMENTS
Many people have contributed greatly to this project. I would like to thank Brendan
Griffin, Neal McNaughton and Alex Bevan for their supervision and advice on various
aspects of the study. Phil Crabb and Thundelarra Exploration kindly provided access to
the Aries drillcore database and sponsored fieldwork at Aries. BHP Exploration also
sponsored a field trip to Aries in 2001. Brian Richardson, Dale Ferguson and Rowan
Ferguson from Thundelarra provided great assistance during fieldwork, as did Caroline
Ludemann and Brendan Griffin from UWA. Discussions with Rob Ramsay, Mike
Baumgartner, Dale Ferguson, Stuart Brown and Mark Doyle about the geology at Aries
were greatly appreciated. Brendan Griffin, Greg Pooley, Sharon Platten and the staff of
the CMM at UWA provided great assistance with all aspects of SEM imaging and
mineral anaysis. Michael Verrall and Greg Hitchen are thanked for their help with SEM
imaging and electron microprobe analysis at the Division of Exploration and Mining,
ARRC, CSIRO, Bentley, W.A. Neal McNaughton, Noreen Veilreicher, April Pickard
and Ian Fletcher assisted with U-Pb SHRIMP analysis, data processing and the
interpretation of results. Jo-Anne Wartho assisted with Ar-Ar analysis at Curtin
University and contributed greatly to the interpretation of the results, including
calculations of ascent duration for the kimberlite magmas. Bill Griffin from GEMOC,
Macquarie University, Sydney, kindly provided proton-probe trace-element data for
garnets and chromites, and Hf-isotope analyses of zircons. Stuart Brown, Mark Doyle,
Jo-Anne Wartho and Stephan Kurszlaukis are thanked for reviewing various parts of the
manuscript. Jenny Bevan generously proof-read the manuscript in very quick time. I
must acknowledge the work of Bob Crossley of Minerex Services in Kalgoorlie for his
section-making wizardry. Jim Richards at United Kimberley Diamonds generously
provided access to company reports on Aries. This study was undertaken with the
permission of the Trustees of the Western Australian Museum, and was jointly funded
by UWA, Thundelarra Exploration and the Western Australian Museum. Finally, I
would like to thank my parents and extended family for their love and support over the
years.
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TABLE OF CONTENTS
ABSTRACT.......................................................................................................................................................2
ACKNOWLEDGEMENTS............................................................................................................................5
TABLE OF CONTENTS................................................................................................................................6
LIST OF FIGURES..........................................................................................................................................8
LIST OF TABLES..........................................................................................................................................10
CHAPTER 1: INTRODUCTION................................................................................................................11
1.1 INTRODUCTORY STATEMENT.......................................................................................................11
1.1.1 PREFACE..............................................................................................................................................11
1.1.2 AIMS AND OBJECTIVES.......................................................................................................................16
1.2 RESEARCH METHODS........................................................................................................................17
1.2.1 FIELDWORK AND PETROGRAPHY.......................................................................................................17
1.2.2 MINERAL CHEMISTRY ANALYTICAL TECHNIQUES.............................................................................17
1.2.3 WHOLE-ROCK GEOCHEMICAL ANALYTICAL TECHNIQUES................................................................19
1.2.4 GEOCHRONOLOGY TECHNIQUES........................................................................................................20
1.2.4.1 40Ar/39Ar laser dating.................................................................................................................20
1.2.4.2 Zircon geochronology................................................................................................................22
1.3 TERMINOLOGY AND NOMENCLATURE.....................................................................................23
1.4 THESIS ORGANISATION....................................................................................................................25
CHAPTER 2: VOLCANOLOGY OF THE ARIES MICACEOUS KIMBERLITE..........................27
2.1 INTRODUCTION....................................................................................................................................27
2.2 GEOLOGICAL SETTING.....................................................................................................................30
2.3 LITHOFACIES IN THE ARIES KIMBERLITE...............................................................................35
2.3.1 HYPABYSSAL LITHOFACIES................................................................................................................35
2.3.1.1 Macrocrystic phlogopite kimberlite (MPK), macrocrystic kimberlite (MK) and macrocrystic
kimberlite breccia (MKB) dykes............................................................................................................35
2.3.1.2 Globular segregationary-textured macrocrystic kimberlite (SK)...........................................41
2.3.1.3 Olivine-phlogopite-richterite kimberlite dykes (OPRK)..........................................................43
2.3.1.4 Macrocrystic serpentine-diopside ultramafic dykes (MSDU).................................................44
2.3.2 DIATREME LITHOFACIES....................................................................................................................45
2.3.2.1 Lithic kimberlite breccia (LKB1 15-50 vol% accidental lithic clasts, LKB2 >50 vol%
accidental lithic clasts)..........................................................................................................................45
2.3.2.2 Basalt breccia (BB) and sandstone breccia (SSB)...................................................................49
2.3.2.3 Bedded lithic kimberlite breccia (BLKB).................................................................................50
2.3.2.4 Juvenile lapilli-rich volcaniclastic kimberlite breccia (VKB).................................................52
2.3.2.5 Quartz-rich volcaniclastic kimberlite breccia (QVKB)...........................................................56
2.3.2.6 Volcaniclastic kimberlite breccia 2 (VKB2).............................................................................57
2.4 DISTRIBUTION OF VOLCANIC LITHOFACIES..........................................................................58
2.5 STRUCTURAL SETTING.....................................................................................................................61
2.6 DISCUSSION............................................................................................................................................61
2.6.1 EVALUATION OF POTENTIAL ERUPTION MECHANISMS AND THE POSSIBLE INFLUENCE OF COUNTRY-
ROCK AQUIFERS ON DIATREME DEVELOPMENT...........................................................................................61
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2.6.2 ORIGIN OF NUCLEATED LAPILLI.........................................................................................................64
2.6.3 ORIGIN OF BEDDED, UPPER DIATREME-FACIES VOLCANICLASTIC ROCKS AND IMPLICATIONS FOR
THE EROSIVE LEVEL OF ARIES DIATREMES..................................................................................................65
2.7 CONCLUSIONS.......................................................................................................................................66
CHAPTER 3: MAGMATIC EVOLUTION AND ASCENT HISTORY OF THE ARIES
MICACEOUS KIMBERLITE.....................................................................................................................69
3.1 INTRODUCTION....................................................................................................................................69
3.2 GEOLOGICAL SETTING.....................................................................................................................72
3.3 PETROGRAPHY.....................................................................................................................................74
3.3.1 MACROCRYSTIC PHLOGOPITE KIMBERLITE (MPK), MACROCRYSTIC KIMBERLITE (MK),
MACROCRYSTIC KIMBERLITE BRECCIA (MKB), AND GLOBULAR SEGREGATIONARY-TEXTURED
MACROCRYSTIC KIMBERLITE (SK)..............................................................................................................76
3.3.2 OLIVINE-PHLOGOPITE-RICHTERITE KIMBERLITE (OPRK)................................................................80
3.3.3 MACROCRYSTIC SERPENTINE-DIOPSIDE ULTRAMAFIC DYKES (MSDU)..........................................81
3.3.4 PHLOGOPITE-BIOTITE-BEARING SERPENTINISED ULTRAMAFIC XENOLITHS.....................................81
3.4 MINERAL CHEMISTRY......................................................................................................................82
3.4.1 TEXTURE AND COMPOSITION OF PHLOGOPITE-BIOTITE.....................................................................83
3.4.1.1 High-Mg phlogopite xenocrysts................................................................................................83
3.4.1.2 High-Ti phlogopite-biotite macrocrysts...................................................................................84
3.4.1.3 Dark brown phlogopite cores (zone 1).....................................................................................91
3.4.1.4 High-Cr phlogopite phenocrysts (zone 2)................................................................................91
3.4.1.5 High-Ti, phlogopite-biotite in rims and groundmass (zone 3)................................................92
3.4.1.6 Groundmass phlogopite (zone 4)..............................................................................................92
3.4.1.7 Barian phlogopite......................................................................................................................93
3.4.1.8 Phlogopite-biotite in xenoliths..................................................................................................93
3.4.2 AMPHIBOLES.......................................................................................................................................94
3.5 WHOLE-ROCK GEOCHEMISTRY...................................................................................................97
3.6 40Ar/39Ar GEOCHRONOLOGY..........................................................................................................102
3.7 DISCUSSION..........................................................................................................................................107
3.7.1 CLASSIFICATION – IS ARIES A KIMBERLITE OR A LAMPROITE?......................................................107
3.7.2 ORIGIN OF HIGH-TI PHLOGOPITE-BIOTITE MACROCRYSTS..............................................................111
3.7.3 VARIATIONS IN MICA CHEMISTRY WITH MAGMA EVOLUTION........................................................114
3.7.4 ORIGIN OF GROUNDMASS SEGREGATIONS, AND ASSOCIATED TRENDS IN THE COMPOSITION OF
GROUNDMASS MINERALS...........................................................................................................................117
3.7.5 GEOCHEMICAL VARIATION BETWEEN HYPABYSSAL PHASES..........................................................118
3.7.6 40Ar/39Ar GEOCHRONOLOGY.............................................................................................................119
3.8 CONCLUSIONS.....................................................................................................................................123
CHAPTER 4: MINERAL CHEMISTRY AND ZIRCON GEOCHRONOLOGY OF
XENOCRYSTS AND ALTERED MANTLE AND CRUSTAL XENOLITHS FROM THE ARIES
MICACEOUS KIMBERLITE...................................................................................................................125
4.1 INTRODUCTION..................................................................................................................................125
4.2 GEOLOGICAL SETTING...................................................................................................................127
4.3 PETROGRAPHY...................................................................................................................................131
4.3.1 ALUMINOUS SPINEL-BEARING SERPENTINISED ULTRAMAFIC XENOLITHS......................................134
4.3.2 CHROMITE-BEARING SERPENTINISED DUNITE.................................................................................136
4.3.3 CHROMIAN SPINEL INCLUSIONS IN OLIVINE MACROCRYSTS...........................................................137
4.3.4 SERPENTINISED ULTRAMAFIC XENOLITHS CONTAINING VARYING PROPORTIONS OF PHLOGOPITE-
BIOTITE, RUTILE, APATITE, PYRITE, AND/OR ZIRCON...............................................................................138
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4.3.5 GRANITE XENOLITHS........................................................................................................................139
4.3.6 ZIRCON MORPHOLOGY AND CATHODOLUMINESCENCE (CL) CHARACTERISTICS..........................141
4.4 MINERAL CHEMISTRY....................................................................................................................141
4.4.1 OLIVINE.............................................................................................................................................141
4.4.2 DIOPSIDE...........................................................................................................................................142
4.4.3 PHLOGOPITE-BIOTITE........................................................................................................................142
4.4.4 SPINELS.............................................................................................................................................143
4.4.5 RUTILE...............................................................................................................................................150
4.4.6 ILMENITE...........................................................................................................................................151
4.4.7 GARNET.............................................................................................................................................152
4.4.8 ZIRCON..............................................................................................................................................152
4.5. THERMOBAROMETRY....................................................................................................................153
4.6 U-Pb SHRIMP GEOCHRONOLOGY...............................................................................................157
4.7 HF-ISOTOPE ANALYSIS...................................................................................................................157
4.8 DISCUSSION..........................................................................................................................................162
4.8.1 GARNET AND SPINEL CHEMISTRY AND THERMOBAROMETRY.........................................................162
4.8.2 SYMPLECTIC TEXTURES IN SPINEL-GROUP MINERALS.....................................................................164
4.8.3 EXSOLUTION MICROSTRUCTURE......................................................................................................166
4.8.4 EVIDENCE FOR MANTLE METASOMATISM........................................................................................167
4.8.5 U-Pb AND Lu-Hf ZIRCON GEOCHRONOLOGY...................................................................................169
4.9. CONCLUSIONS....................................................................................................................................171
CHAPTER 5: CONCLUSIONS.................................................................................................................173
REFERENCES.............................................................................................................................................178

LIST OF FIGURES
Figure 1.1. Map showing the location of the Aries kimberlite and the north, east and west Kimberley
kimberlite-lamproite provinces in the Kimberley region of Western Australia.
Figure 2.1. Map showing the location of the Aries kimberlite and the north, east and west Kimberley
kimberlite-lamproite provinces in the Kimberley region of Western Australia.
Figure 2.2. A simplified geological map of the Phillips Range area showing basement geology and the
location of the Aries kimberlite.
Figure 2.3. The stratigraphy of the Kimberley and Speewah Basins.
Figure 2.4. Geological plan of the Aries kimberlite at the 350 m relative level (RL), 50 m below the
current surface.
Figure 2.5. Geological cross-sections of the Aries kimberlite: (a) central lobe - 9920 mN, and (b) north
lobe - 10235 mN (local grid).
Figure 2.6. Graphic log of DDH AN7, from the north lobe of the Aries kimberlite.
Figure 2.7. Photographs of uniform- and globular segregationary-textured macrocrystic phlogopite
kimberlite.
Figure 2.8. Photographs of lithic kimberlite breccias from the north lobe diatreme.
Figure 2.9. Photographs of spherical nucleated lapilli.
Figure 2.10. Photographs of juvenile lapilli-rich volcaniclastic kimberlite breccia (VKB), bedded lithic
9
kimberlite breccia (BLKB), and volcaniclastic kimberlite breccia (VKB2), from the north and central
lobe diatremes.
Figure 2.11. Graph of maximum lithic clast size versus depth in DDH AN7 for the VKB unit.
Figure 2.12. Photomicrographs showing poorly- to non-vesicular, ash-sized, juvenile kimberlite
fragments in VKB.
Figure 3.1. Map showing the location of the Aries kimberlite and the north, east and west Kimberley
kimberlite-lamproite provinces in the Kimberley region of Western Australia.
Figure 3.2. Geological plan of the Aries kimberlite at the 350 m relative level (RL), 50 m below the
current surface.
Figure 3.3. Back Scattered Electron (BSE) images of phlogopite-biotite macrocrysts and phenocrysts.
Figure 3.4. BSE images of groundmass segregations in macrocrystic phlogopite kimberlite (MPK) and
olivine-phlogopite-richterite kimberlite (OPRK).
Figure 3.5. Major-element variation diagrams for phlogopite-biotite from the Aries kimberlite and
contained xenoliths.
Figure 3.6. Trace-element variation diagrams for phlogopite-biotite from the Aries kimberlite and
contained xenoliths.
Figure 3.7. Ti (apfu) v Na/K for amphiboles from the Aries kimberlite.
Figure 3.8. (a) Primitive mantle-normalised trace-element abundance patterns, and (b) chondrite-
normalised REE profiles for hypabyssal lithologies from the Aries kimberlite.
Figure 3.9. Ar diffusion profile for a high-Ti phlogopite-biotite macrocryst from the Aries kimberlite.
Figure 3.10. Al O (wt%) v FeO (wt%) for the Aries micas with comparative data.
2 3
Figure 4.1. Map showing the location of the Aries kimberlite and the north, east and west Kimberley
kimberlite-lamproite provinces in the Kimberley region of Western Australia.
Figure 4.2. Geological plan of the Aries kimberlite at the 350 m relative level (RL), 50 m below the
current surface.
Figure 4.3. Back-scattered electron images of spinel-group minerals, rutile and phlogopite from the Aries
kimberlite and contained xenoliths.
Figure 4.4. Back-scattered electron (BSE) images of mineral exsolution textures in the Aries
serpentinised ultramafic xenoliths.
Figure 4.5. Cathodoluminescence (CL) and back-scattered electron (BSE) images of zircon from
serpentinised ultramafic xenoliths from the Aries kimberlite.
Figure 4.6. Major-element variation diagrams for spinel-group minerals from the Aries kimberlite and
xenoliths.
Figure 4.7. Cr/(Cr+Al)-Fe2+/(Fe2++Mg) plots comparing the uniform-textured core compositions of spinel
xenocrysts and spinels from ultramafic xenoliths from the Aries kimberlite to fields for mantle
xenoliths from kimberlites (a) and basalts (b).
Figure 4.8. Trace-element variation diagrams for spinel-group minerals from the Aries kimberlite and
xenoliths. (a) Ti vs Ni; (b) Ti vs Co; (c) Ti vs V; (d) Ti vs Zn.
Figure 4.9. Y-Zr and Y/Ga-Zr/Y plots for garnet xenocrysts from the Aries kimberlite.
Figure 4.10. T -P plot for garnet xenocrysts from the Aries kimberlite.
Ni Cr
Figure 4.11. Cr O (wt%) versus T (˚C) plot for chromain spinel xenocrysts from heavy mineral
2 3 Zn
concentrates from the Aries kimberlite.
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Figure 4.12. Histogram of T (˚C) for chromian spinel xenocrysts from heavy mineral concentrates from
Zn
the Aries kimberlite.
Figure 4.13. SHRIMP U-Pb zircon concordia diagrams for a granite xenolith and two serpentinised
ultramafic xenoliths from the Aries kimberlite.
Figure 4.14. Th-U plot for zircons from granite and serpentinised ultramafic xenoliths from the Aries
kimberlite.

LIST OF TABLES
Table 3.1. Petrography of the Aries kimberlite
Table 3.2. Representative electron microprobe and SEM-EDS analyses of phlogopite-biotite from the
Aries kimberlite.
Table 3.3. Representative LA-ICPMS trace-element analyses of phlogopite-biotite from the Aries
kimberlite and contained xenoliths.
Table 3.4. Representative electron microprobe analyses of amphibole, sanidine and andradite from the
Aries kimberlite.
Table 3.5. (a) Whole-rock major-element analyses of hypabyssal lithologies from the Aries kimberlite.
(b) Whole-rock trace-element analyses of hypabyssal lithologies from the Aries kimberlite.
(c) Whole-rock major- and trace-element ratios for hypabyssal lithologies from the Aries kimberlite.
Table 3.6. Summary of 40Ar/39Ar analyses (2 sigma errors) from mica grains from the Aries kimberlite,
including the modelling results from one 40Ar* diffusion profile.
Table 3.7. A comparison of the mineralogy of the Aries kimberlite with group 2 kimberlites (orangeites)
and lamproites.
Table 4.1. Texture and composition of spinel-group minerals from the Aries kimberlite and contained
xenoliths.
Table 4.2. Representative analyses of olivine, diopside and phlogopite-biotite from the Aries xenoliths.
Table 4.3. Representative analyses of spinel-group minerals, ilmenite and rutile from the Aries kimberlite
and contained xenoliths.
Table 4.4. Trace-element chemistry of spinel xenocrysts and spinels from serpentinised xenoliths.
Table 4.5. Trace-element chemistry of chromian spinel xenocrysts from heavy mineral concentrates
(proton probe).
Table 4.6. LA-ICPMS trace-element analyses of rutile from a phlogopite-rutile-bearing serpentinised
xenolith (AN29-234.15m).
Table 4.7. Trace-element chemistry of garnet xenocrysts from the Aries kimberlite.
Table 4.8. U-Th-Pb SHRIMP zircon data for granite and serpentinised ultramafic xenoliths from the
Aries kimberlite.
Table 4.9. Hf isotope data for zircons from the Aries ultramafic xenoliths.