Structure and Evolution of the Australian Continent

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Structure and Evolution
of the Australian Continent
Jean Braun
Jim Dooley
BruceG oleby
Rob van der Hilst
ChrisK lootwijk
Editors
GeodynamiScesr ies Volume 26
AmericaGne ophysicUanl ion
Washington,
Geodynamics Series
1. Dynamics of Plate Interiors
A. W. Bally, P. L. Bender, T. R. McGetchin, and R. I. Walcott (Editors)
2. Paleoreconstruction of the Continents
M. W. McEIhinny and D. A. Valencio (Editors)
3. Zagros, Hindu Kush,H imalaya, Geodynamic Evolution
H. K. Gupta and F. M. Delany (Editors)
4. Anelasticity in the Earth
F. D. Stacey, M. S. Patterson, and A. Nicholas (Editors)
5. Evolution of the Earth
R. J. O'Connell and W. S. Fyfe (Editors)
6. Dynamics of Passive Margins
R. A. Scrutton (Editor)
7. Alpine-Mediterranean Geodynamics
H. Berckhemer and K. Hs0 (Editors)
8. Continental and Oceanic Rifts
G. P61masonP, . Mohr,K . Burke,R . W. Girdler,R . J. Bridwella, nd G. E.S igvaldason(E ditors)
9. Geodynamics of the EasternP acific Region, Caribbean, and Scotia Arcs
R6mon Cabr(cid:127), S. J. (Editor)
10. Profileso f Orogenic Belts
N. Rast and F. M. Delaney (Editors)
11. Geodynamics of the Western Pacific-lndonesian Region
Thomas W. C. Hilde and Seiya Uyeda (Editors)
12. Plate ReconstructionF rom Paleozoic Paleomagnetism
R. Van der Voo, C. R. Scotese, and N. Bonhommet (Editors)
13. Reflection Seismology:A Global Perspective
Muawia Barazangi and Larry Brown (Editors)
14. Reflection Seismology:T he Continental Crust
Muawia Barazangi and LarryB rown (Editors)
15. Mesozoic and Cenozoic Oceans
Kenneth J. Hs0 (Editor)
16. Composition, Structure,a nd Dynamics of the Lithosphere-AsthenosphereS ystem
K. Fuchs and C. Froidevaux (Editors)
17. Proterozoic Lithospheric Evolution
A. Krbner (Editor)
18. Circum-Pacific Orogenic Beltsa nd Evolutiono f the Pacific Ocean Basin
J. W. H. Monger and J. Francheteau (Editors)
19. Terrane Accretion and Orogenic Belts
Evan C. Leitch and ErwinS cheibner (Editors)
20. Recent Plate Movements and Deformation
K. Kasahara (Editor)
21. Geology of the USSR:A Plate-Tectonic Synthesis
L. P. Zonenshain, M. I. Kuzmin,a nd L. M. Natapov B.M. Page (Editor)
22. Continental Lithosphere: Deep Seismic Reflections
R. Meissner,L . Brown,H . D0rbaum, W. Franke, K. Fuchs,F . Selferr( Editors)
23. Contributionso f Space Geodesy to Geodynamics: Crustal Dynamics
D. E. Smith, D. L. Turcotte (Editors)
24. Contributions of Space Geodesy to Geodynamics: Earth Dynamics
D. E. Smith, D. L. Turcotte (Editors)
25. Contributionso f Space Geodesy to Geodynamics:T echnology
D. E. Smith,D . L. Turcotte
CONTENTS
Preface
(cid:127)1.B raun,J . C. Dooley, B. R. Goleby,R . D. van der Hilst, and C. T. Klootwijk iv
SecularV ariationi n the Compositiono f SubcontinentaLli thosphericM antle:G eophysicaal ndG eodynamic
Implications
W. L. Griffin, S. Y. O'Reilly,C . G. Ryan, O. Gaul, and D. A. Ionov 1
HypotheseRs elevantt o CrustaGl rowth
A. L. Hales 27
UpperM antleS tructurbe eneathA ustraliafr omP ortableA rrayD eployments
R. D. van der Hilst, B. L. N. Kennett, and T. Shibutani 39
Mappingo f GeophysicaDl omainsin theA ustralianC ontinentaCl rustU singG ravitya ndM agneticA nomalies
P. Wellman 59
ComplexA nisotropyin theA ustralianL ithospherfero mS hear-wavSep littingin Broad-banSdK SR ecords
G. Clitheroe and R.. D. van der Hilst 73
A Brief Reviewo f Differencesin LithospherSe eismicP ropertieUs nderW esterna ndE asternA ustraliaS timulated
by Seismogramfsro mt he MarryatC reekE arthquakeosf 1986
B. (cid:127)1. Drummond 79
LithospheriSct ructurien SoutheasAtu straliaa: ModelB asedo n Gravity,G eoida ndM echanicaAl nalyses
Y. Zhang,E . ScheibnerB, . E. Hobbs,A . Ord, B. J. Drummonda, ndS . J. D. Cox 89
The Mount Isa GeodynamicT ransect-C rustalI mplications
B. R. Goleby,T . MacCreadyB, . J. Drummonda, ndA . G. Goncharov 109
Intra-Crusta"l SeismicIs ostasyi"n the BalticS hielda ndA ustralianP recambriaCn ratonsf rom Deep Seismic
Profilesa ndt he Kola SuperdeepB ore Hole Data
A. G. GoncharovM, .D. LizinskyC, . D. N. Collins,K . A. Kalnin,T . N. Fomin,B . d. DrummondB, . R. Goleby,a ndL .
N. Platonenkova 119
ContrastinSgt yleso f LithospherDice formatioAnl ongt heN orthernM argino f theA madeuBs asinC, entral
Australia
J. Braun and R. Shaw 139
Extensionin the FitzroyT rough,W esternA ustraliaa: n Exampleo f ReactivationT ectonics
(cid:127). Braun and R. Shaw 157
Granite-GreenstonZeir conU -Pb Chronologyo f the Gum CreekG reenstonBe elt, SouthernC rossP rovinceY, ilgarn
Craton:T ectonicI mplications
Q. WangJ, . Beesona, ndI . H. Campbell
PREFACE
Recentg eophysicagl,e ochemicaaln dg eologicaslt udiesh avel edt o a muchi mproved
understandinogf t he structuraen de volutiono f theA ustralianc ontinenftr omi ts Archaean
nucletio itsp resent-damyo rphologTyh. isn eww ealtho f informatiohna sr aiseda dditional
questionso n the continent'gse ologicapl ast,a nd has led to the formulationo f new
hypotheseosn continentagl rowtha nd dynamicsw hich will servet o inspiref urther
investigationTsh. isv olumec ompiletsh e mostc urrengt eologicaaln dg eophysicdala ta
pertainingto the formationa nde volutiono f theA ustralianco ntinentth roughg eological
time. Althought he mainf ocuso f thism onograpihs the structuraen de volutiono f the
Australianc ontinenmt, anyo f theo bservationasn di nterpretationasre d iscusseidn a global
framework and are relevant for studies of other continents.
The contributorsd escribeo ur stateo f knowledgeo n the structureo f the Australian
continenat,n do urp resenut nderstandinogf howt hiss tructureev olvedth roughg eological
timeb y accretioonf thec entraPl roterozoiccr ustabl locksa nde asternP hanerozoitce rranes
to the Archaean nuclei of western Australia.
New data are presentedfr om a wide range of disciplinesin cludings eismology,
petrophysicpse,t rochemistgrye,o chronologayn,d p otentiafli elds tudiesT. he datai nclude
thes eismic-velocistytr ucturuen derm ostp artso f thec ontinentto depthso f 1000k m from
the inversiono f seismicd ataf roma portablea rrayo f broad-bansde ismomete(rtsh e SKIPPY
experiment)d, eepr eflections eismics oundingos,b servationosf seismica nisotropfyro m
shear-wavsep littingh,i gh-resolutigorna vitya ndm agnetiacn omalym apsm, odala ndt race
elementd ataf rom xenolithsa, ndh igh-resolutiosne nsitiveh ighr esolutionio n microprobe
(SHRIMP) U-Pb zircond atingo f Archaeanro cksi n theY ilgarnB lock.
Hypotheseasn dm odelsa ref ormulatecdo ncernintgh eg rowtha ndr e-structurinogf the
continentht rougha largen umbeor f tectonice ventss, ucha st he ProterozoiIcs anO rogeny
of northeasternA ustralia,t he late PalaeozoicA lice SpringsO rogenyo f central and
northwesterAnu straliaa, ndt he Mesozoicc ontinentaelx tensionas sociatewdi th the opening
of the TasmanS eaa longt he southeastermna rgino f the continent.
This volume is basedo n papersp resenteda t the 1996 WesternP acific Geophysics
Meeting in Brisbane. Them eetingw asc o-sponsorbedy the SpecialisGt roupo n Solid
EarthG eophysicosf the GeologicaSl ocietyo f Australiaa ndt he AmericanG eophysical
Union. The editorsw ish to thank the many individualsw ho have contributedto this
monograpahn, de specialltyh ea uthorasn dr eviewersw,h ow orkedd iligentltyo permitit s
timely publication.
Finallyw, e hopeth att hisA ustraliapne rspectivwei ll helpo therE arths cientisttos i mprove
ouru nderstandinogf the evolutiona ndd ynamicso f theE arth'sc ontinents.
Jean Braun
Jim Dooley
BruceG oleby
Rob van der Hilst
ChrisK lootwijk
Editors
Secular Variation in the Composition of Subcontinental Lithospheric
Mantle: Geophysical and Geodynamic Implications
W. L. Griffin
National Key Centref or the GeochemicaEl volutiona nd Metallogenyo f ContinentsS, choolo f Earth SciencesM, acquarie
University,S ydney,N SW 2109, Australia, and
CSIRO Explorationa nd Mining, P.O. Box 136, North Ryde, NSW, Australia
SuzanneY . O'Reilly
National Key Centref or the GeochemicaEl volutiona nd Metallogenyo f ContinentsS, choolo f Earth SciencesM, acquarie
University, Sydney,N SW, Australia
C. G. Ryan
CSIRO Explorationa nd Mining, P.O. Box 136, North Ryde, NSW, Australia
O. Gaul and D. A. Ionov
National Key Centref or the GeochemicaEl volutiona nd Metallogenyo f ContinentsS, choolo f Earth SciencesM, acquarie
University, Sydney,N SW, Australia
A synthesiso f modal and trace element data for mantle-derivedp eridotites
and the compositions of over 8000 mantle-derived Cr-pyrope garnets,
documents a secular and apparently irreversible change in the chemical
composition of newly created lithospheric mantle throughout the Earth's
history. This change suggestsa n evolution in fundamentall arge-scaleE arth
processes;i t has important implications for the interpretation of seismic
tomography, and means that lithosphere erosion will have major tectonic
consequences. The average composition of peridotitic garnet xenocrysts
from volcanic rocks is strongly correlatedw ith the tectonothermala ge of the
continental crust penetrated by the eruptions. Garnets derived from
harzburgitico r lherzolitic rock types can be recognisedb y comparisonw ith
data from mantle-derived xenoliths, and used to estimate relative abundances
of these rock types in individual mantle sections. Subcalcich arzburgitesa re
found only in lithosphericm antle beneathA rchean terrains;m ildly subcalcic
harzburgitesa re common beneath Archean terrains, less abundant beneath
Proterozoic terrains, and essentially absent beneath terrains with
tectonothermaal ges less than 1 Ga. Garnetsf rom lherzolites( clinopyroxene-
bearingp eridotites)s how a decreaseo f mean Cr contenta nd Zr/Y, and a rise
in Y and Y/Ga, with decreasingc rustala ge. Modeling using empirical element
distributionc oefficientss uggeststh at thesec hangesr eflect a rise in (cpx+gnt)
Structure and Evolution of the Australian Continent
Geodynamics2 6
Copyright1 998b y the AmericanG eophysicaUl nion.
2 GRIFFIN ET AL.
and cpx/gnt, and a decreasei n mg#, from Early Proterozoic time to the
present. The Archean-Proterozoibco undaryr epresentsa major changei n the
processesth at form continentall ithosphericm antle; since 2.5 Ga there has
been a pronouncedb, ut more gradual,s ecularc hangei n the nature of these
processes. Actualistic models of lithospheref ormation based on modem
processesm ay be inadequate,e ven for Proterozoict ime. The correlation
between mantle type and crustal age indicatest hat the continentalc rust and
the underlying lithosphericm antle are formed together, and generally stay
coupledt ogetherf or periodso f eons. The stabilitya nd thicknesso f Archean
lithosphericm antlei s directly relatedt o its low density,w hich in turn reflects
both its high degreeo f depletioni n basaltic componentsa, nd its low Mg/Si.
These chemical characteristics produce high seismic velocities, and
compositionalf actors may accountf or at least half of the velocity contrast
betweenA rchean and youngera reas,s eeni n seismict omography. The higher
density and mantle heat flow of younger, less depleted mantle sections
imposess evere limits on their thicknessa nd ultimate stability, becauset he
cooler upper parts of theses ectionsw ill be negativelyb uoyantr elative to the
underlying asthenosphere.
1. INTRODUCTION measured in many Archean cratons [Morgan, 1995].
Archeanm odel ageso n inclusionsin diamonds[ Richardson
The aim of this paper is to examine changes in the et al., 1984] and Archean Re-Os depletiona geso n mantle-
compositiono f the subcontinentalli thosphericm antle from derived xenoliths in kimberlites from Archean cratons
Archeant ime to the present. The naturea nd scaleo f these [Pearsone t al., 1995] stronglys uggestt hat the lithospheric
variationsr epresentf undamentailn formationr elatingt o the keels beneath these areas formed in Archean time, and have
geodynamice volution of Earth, and changest hrought ime persisted to the present. The repeated intrusion of
in the processes that have produced the continents. diamondiferousk imbeditesi n somea reas( e.g. the Kaapvaal
Understandingo f the evolutiono f thesep rocessesim pacts Craton of South Africa, from at least 1600 Ma to 80 Ma
on our ideas about major aspects of geology, from the [Smith et al., 1995]) also testifiest o the long-terms tability
compositiono f the Earth, to the formationa nd localisation of at least some Archean keels.
of large ore deposits.K nowledgeo f the compositiono f the This general model of lithospherick eels beneaths ome
mantle is essential also for realistic modeling of Archean cratonsr aises the fundamentalq uestiono f their
geophysicadl ata,e speciallys eismica ndg ravity. origin and the reasonsfo r their persistencteh roughg eologic
Diamond exploration activities have made a major time. Are the causest ectonic, thermal or compositional?
contributiont o understandingth e natureo f the continental This paper will briefly examine the evidencef rom mantle-
lithosphere. One fundamentalo bservationf rom this body derived xenoliths, and then expand on this using a large
of work is summarisedi n Clifford's Rule (as expandedb y body of compositionald ata on mantle-derivedg arnets,t o
Janse[ 1994]): kimberlites with economicc oncentrationso f trace the evolutiono f subcontinentaml antle throught ime.
diamondsa re restrictedt o cratonsw ith crustala gesg reater
than or equal to 2.5 Ga, and diamondiferousla mproitesa re
2. DATA BASES AND DEFINITIONS
restrictedt o areasw ith crustala gesb etween2 .5 and 1.6 Ga.
Combined with experimentald ata on diamonds tability in
the mantle, this observationh as led to the concept of a Two data basesa re used in this paper. One consistso f
thick cold "root" or "keel" beneath Archean cratons, and its averagedd atao n garnetc oncentratefsr om volcanicr ockso f
corollary, that the lithospheric mantle beneath younger widely different agesa nd tectonics ettings( Table 1). The
terrainss houldb e thinnero r hotter,o r both,t o explaint he other is a compilationo f modal and compositionadl ata on
scarcity of diamonds in regions with Proterozoic and garnet peridotite xenoliths from a variety of tectonic
Phanerozoicc rustala ges[ Boyd andG urney,1 986]. settings( Table 2). All of the garnetsu sed in Table 1 are
Thesei deash ave beenl argely substantiatebdy the results Cr-pyropes, judged on the basis of composition to be
of seismict omographys tudies,w hich showr egionso f high derived from ultramaficw all rocksd uring ascento f the host
seismic velocity extending to 150-300 km depth beneath volcanic rock. Many of the samples are derived from
someA rcheanc ratons,b ut not beneatht he youngerp artso f diamonde xplorationa ctivities;o thersh ave beenc ollectedo r
continents[ Suet al., 1994]. These high-velocityv olumes analyseds pecificallyf or the purposeso f this research.T he
are interpreted as being cooler than the lower-velocity garnetsh ave been analysedf or major elementsb y electron
volumes, reflecting the generally lower surfaceh eat flow microprobe, and for trace elements either by proton
,--:(cid:127). (cid:127) (cid:127). o o o,-:. o o,-:.'":. (cid:127)
Table 2. Xenolith data
Locstion/ Sample Mode GntC ompositionO livine Bulk Rock
reference no. oliv opx cpx gnt cpx/gnt cpx+gnt Cr203 CaO %Fo A1203 CaO MgO mg#
% % % % % % % % % % %
ARCHONS
Kaapvaal Craton EJB 4 60.8 31.0 3.0 4.2 0.71 7.2 4.49 5.13 92.1 1.51 1.28 42.43 91.9
Cox et al., 1987 EJb 48 63.1 30.5 1.6 4.5 0.36 6.1 4.84 5.15 92.9 1.13 0.64 45.53 92.8
mb3 60.7 31.1 2.5 5.7 0.44 8.2 4.11 4.84 92.5 1.65 0.92 43.84 92.5
mb 7 52.4 39.3 1.5 5.1 0.29 6.6 4.75 5.24 92.9 1.43 0.95 44.00 92.8
mb 12 63.7 29.5 2.0 4.4 0.45 6.4 4.80 5.04 92.3 1.47 1.03 42.95 92.6
mb 13 66.5 27.2 0.7 4.4 0.16 5.1 4.45 5.00 92.8 1.56 0.74 43.39 92.9
Cox et al., 1973 Ibm9 48.7 40.6 2.7 6.7 0.40 9.4 4.00 5.07 92.3 2.45 1.36 38.84 91.8
11 47.5 47.0 0.4 5.0 0.08 5.4 5.83 5.24 92.3 1.41 0.75 41.12 92.2
12 42.0 38.4 9.2 10.4 0.88 19.6 3.96 4.96 83.4 3.60 2.90 33.45 80.9
17 49.1 44.4 0.1 6.1 0.02 6.2 3.74 4.80 92.6 2.45 0.89 38.33 92.9
32 27.7 43.8 4.2 20.4 0.21 24.6 3.61 4.55 89.0 4.71 2.29 33.94 88.2
33-c 13.9 20.7 49.0 16.4 2.99 65.4 2.13 4.72 87.5 5.02 9.10 24.89 86.6
36-a 54.0 23.0 12.0 11.0 1.09 23.0 2.47 4.79 87.4 3.23 3.20 35.38 86.7
37 42.2 31.1 13.0 13.7 0.95 26.7 2.33 4.68 87.5 4.10 6.67 27.33 87.1
38 67.4 22.8 2.1 7.7 0.27 9.8 1.73 4.46 88.6 2.27 3.55 30.34 86.1
bd 1355 54.0 34.0 4.0 7.0 0.57 11.0 4.21 5.22 92.5 1.50 1.03 41.80 92.8
Boyd et al., 1993 frb932 61.4 30.0 0 7.3 0 7.3 3.78 3.42 93.9 1.67 0.61 43.69 93.6
frb978 64.7 28.3 0 5.1 0 5.1 4.93 3.94 93.5 1.23 0.76 43.73 93.3
frb 1013 65.2 27.4 0 4.5 0 4.5 7.86 4.18 93.5 0.97 0.71 43.58 92.4
phn4 254 63.6 32.1 0 3.9 0 3.9 6.16 4.00 93.5 0.99 0.32 43.77 93.7
phn5 596 77.3 18.3 0 3.5 0 3.5 9.47 4.84 92.6 0.68 0.30 44.13 92.3
frb 1402 69.8 25.2 0 3.7 0 3.7 4.51 3.92 93.2 0.89 0.29 43.70 92.5
frb 1404 57.6 35.8 0 5.8 0 5.8 4.14 3.77 93.5 1.39 0.45 43.07 93.2
frb 1409 57.6 35.0 0 6.8 0 6.8 4.23 3.96 93.7 1.57 0.59 43.04 93.4
frb 1422 63.7 30.9 0 4.5 0 4.5 4.25 3.54 93.5 1.11 0.35 43.79 93.2
frb 1447 65.3 28.9 0 4.7 0 4.7 4.39 3.77 93.4 1.13 0.32 43.75 93.1
118 47.4 40.2 2.8 9.6 0.29 12.4 2.58 4.64 92.9 2.41 1.03 41.35 92.3
175 58.4 29.7 7.4 4.5 1.66 11.9 2.30 4.60 92.2 1.32 1.70 42.61 92.2
181 82.2 15.1 0.4 2.4 0.16 2.7 6.22 5.53 93.2 0.55 0.33 48.14 92.9
197 57.1 20.1 8.8 14.0 0.63 22.8 2.17 3.87 91.7 3.47 2.14 40.13 90.1
127 64.4 31.6 0 4.0 0 4.0 5.89 4.26 92.7 1.09 0.48 45.41 92.8
168 63.1 31.9 0 5.0 0 5.0 5.92 4.21 92.7 1.15 0.51 44.80 92.3
184 72.3 22.0 0 5.6 0 5.6 4.29 3.68 93.8 1.23 0.56 46.79 93.5
Carswell et al., 1984 PTH207 64.9 31.3 2.2 1.6 1.34 3.8 8.34 6.90 92.0 0.68 0.73 44.27 92.6
PTH400 63.4 28.7 6.6 1.3 5.05 7.9 4.34 5.45 91.4 0.42 1.35 43.07 90.7
PTH403 61.7 29.1 3.4 5.8 0.58 9.2 6.80 6.02 91.9 1.19 1.01 42.36 91.0
PTH405 60.3 33.6 1.3 4.7 0.28 6.1 6.33 5.35 92.5 1.08 0.58 43.66 91.8
PTH409 67.2 29.8 1.2 1.8 0.69 3.0 7.70 6.57 92.5 0.61 0.45 44.97 92.7
Danchin, 1979 118 47.4 40.2 2.8 9.6 0.29 12.4 2.58 4.64 80.7 2.41 1.03 41.35 92.3
175 58.4 29.7 7.4 4.5 1.66 11.9 2.30 4.60 58.0 1.32 1.7 42.61 92.2
181 82.2 15.1 0.4 2.4 0.16 2.7 6.22 5.53 74.8 0.55 0.33 48.14 92.9
197 57.1 20.1 8.8 14.0 0.63 22.8 2.17 3.87 74.3 3.47 2.14 40.13 90.1
168 63.1 31.9 0.0 5.0 0.00 5.0 5.92 4.21 80.1 1.15 0.51 44.80 92.3
184 72.3 22.0 0.0 5.6 0.00 5.6 4.29 3.68 79.7 1.23 0.56 46.79 93.5
Lashaine 775 74.2 15.7 0 8.5 0 8.5 4.51 2.85 92.7 2.06 0.42 45.6 94.1
Reid et al., 1974 797 62.7 28.1 1.3 4.8 0.27 6.1 4.49 4.39 92.7 1.42 0.57 44.3 92.8
Rhodes& Dawson, 796 72.6 18.0 0.9 6.7 0.13 7.6 3.53 4.63 92.2 1.67 0.59 45.0 92.2
1974 740 68.0 20.7 2.0 8.1 0.25 10.1 2.78 4.92 92.0 2.09 0.91 44.0 92.1
794 69.2 21.0 2.3 5.8 0.40 8.1 3.59 5.07 92.0 1.53 0.87 44.2 92.2
776a 77.5 10.7 5.0 6.5 0.77 11.5 4.21 4.44 91.7 1.53 1.26 44.1 91.2
782 79.0 11.9 0.8 4.4 0.18 5.2 3.44 3.93 91.3 1.16 2.55 44.3 91.4
TECTONS
The Thumb 112 82 11 4 2 2.00 6.0 5.81 5.94 86.8 1.14 1.28 41.4 85.6
Ehrenberg1, 982 ao82 61 16 16 9 1.78 25.0 2.40 5.20 89.7 2.60 3.26 39.0 88.2
110 62 14 15 9 1.67 24.0 1.68 4.66 90.4 3.52 2.96 38.0 89.3
128 64 11 14 11 1.27 25.0 3.06 5.01 91.1 3.40 2.63 39.8 90.0
ro77 57 18 14 11 1.27 25.0 2.75 2.80 39.3 90.2
qo77 72 22 2.0 3.0 0.67 5.0 2.87 6.03 91.2 1.07 0.96 44.3 90.5
ho77 80 15 2.7 2.2 1.23 4.9 2.71 5.93 91.7 0.89 0.82 45.2 91.2
io78 70 20 3.3 4.4 0.75 7.7 1.31 1.24 42.7 91.3
Notes:B lanke ntries= no data;* averagefo r gntp eridotite(sN ixona ndB oyd,1 979)a ndS terae t al., (1989)
Table 2. Xenolith data continued
Location/ Sample Mode GntC ompositionO livine Bulk Rock
reference no. oliv opx cpx gnt cpx/gnt cpx+gnt Cr203 CaO %Fo A1203 CaO MgO mg#
% % % % % % % % % % %
TECTONS ctd
The Thumb ctd 126 88 9 0.7 2.0 0.35 2.7 6.09 6.32 91.4 0.54 0.52 47.0 91.5
Ehrenberg1, 982 117 96 3 1.0 1.0 1.00 2.0 0.24 0.44 47.6 91.6
no77 74 19 1.7 3.5 0.49 5.2 3.57 6.40 90.8 1.54 0.82 43.9 91.7
156 79 19 1.0 1.0 1.00 2.0 0.97 0.60 45.8 91.7
104 76 18 3.0 3.0 1.00 6.0 0.54 0.72 45.3 91.8
120 81.0 16.0 1.0 2.0 0.50 3.0 0.53 0.50 47.2 91.9
105 81 16 1.0 2.0 0.50 3.0 4.10 6.26 92.2 1.21 1.18 44.9 92.1
Malaita plm4 002 66 10 15 4 3.75 19.0 1.01 5.02 89.5* 3.55 3.58 39.2 88.6
Neal, 1988 plm4 009 57 12 20 1 20.00 21.0 0.61 4.84 89.5* 4.93 4.78 36.5 88.6
plm4 013 56 12 13 10 1.30 23.0 1.32 6.00 89.5* 4.99 4.47 36.5 88.3
phn4 016 60 12 24 2 12.00 26.0 0.77 5.15 89.5* 3.48 5.23 37.8 89.2
phn4 034 66 5 9 2 4.50 11.0 1.78 5.14 89.5* 3.52 3.78 38.9 89.0
phn4 064 66 5 17 8 2.13 25.0 0.90 4.93 89.5* 4.59 3.92 38.4 88.3
phn4 067 58 5 28 6 4.67 34.0 0.84 4.95 89.5* 4.76 6.08 35.6 88.8
plm4 069 60 8 15 7 2.14 22.0 1.32 5.89 89.5* 4.51 4.64 37.2 88.3
crn 209 66 8 16 2 8.00 18.0 4.90 5.54 89.5* 2.95 2.17 39.9 89.0
crn 213 61 12 18 4 4.50 22.0 0.68 4.79 89.5* 5.11 4.01 37.8 88.7
Pali-Aike TM 2 60 20 20 10 2 30 1.23 5.05 87* 4.0 3.0 37.7 88.7
Stern et al., 1989 TM1 55 15 15 15 1 30 1.28 4.96 87* 4.1 3.2 37.6 89.1
BN4 50 20 15 15 1 30 1.20 4.96 87* 4.6 3.4 36.9 88.3
BN35 45 25 15 15 1 30 1.16 4.97 87* 4.3 3.3 37.1 89.3
LS4 65 20 10 5 2 15 1.69 5.13 87* 3.8 2.9 38.3 89.6
LS 101 60 20 10 10 1 20 1.75 5.11 87* 3.9 3.0 37.9 89.2
LS33 55 20 15 10 2 25 1.90 5.02 87* 3.9 3.0 37.3 89.1
Vitim 313-1 60.8 13.7 12.1 13.4 0.90 25.5 1.18 4.82 90.1 4.37 3 38.50 89.6
Ionov et al., 1993 313-2 58.0 22.1 13.7 6.3 2.17 20.0 1.32 4.96 89.8 3.23 3.18 39.70 90.2
Ionov,u npubl. 313-3 61.1 12.7 14.3 11.9 1.20 26.2 1.14 4.9 90.1 4.03 3.35 38.65 89.7
313-5 64.0 11.2 13.4 11.4 1.18 24.8 1.52 4.83 90.5 3.95 3 39.10 89.9
313-6 63.7 12.1 12.9 11.3 1.14 24.2 1.59 5.11 90.4 3.88 3.04 38.95 89.3
313-8 57.0 13.4 15.6 14 1.11 29.6 1.23 4.9 90.5 4.82 3.7 37.40 89.5
313-37 60.9 16.8 15.5 6.5 2.38 22.0 1.18 5.18 90.2 3.27 3.45 39.20 90.1
313-54 60.6 13.3 14.7 11.4 1.29 26.1 1.32 4.87 90.7 4.1 3.42 38.70 89.7
313-104 57.6 16.8 14.1 11.1 1.27 25.2 1.06 4.94 89.7 4.32 3.43 38.52 89.5
313-105 59.8 19.5 12.1 8.0 1.51 20.1 1.11 4.71 90.0 3.41 2.83 39.15 89.8
313-106 63.2 15.4 13.1 8.4 1.56 21.5 1.01 4.85 89.8 3.29 3.04 39.72 89.5
313-110 61.4 14.3 12.3 11.7 1.05 24.0 1.2 4.95 90.5 4.01 3.07 39.56 89.9
313-240 66.7 14.1 11.3 7.9 1.43 19.2 1.16 4.99 90.0 3.19 2.69 41.06 89.9
313-241 61.3 16.8 11.9 10.0 1.19 21.9 1.15 4.95 89.9 3.62 2.84 39.55 89.4
314-74 67.9 16.5 10.4 3.9 2.67 14.3 1.16 5.05 90.9 2.84 2.35 41.82 90.4
314-580 65.6 14.9 13.9 3.5 3.97 17.4 1.54 5.04 90.8 3.17 2.68 40.41 89.1
313-113sg 70.2 8.6 13.3 7.6 1.75 20.9 0.99 4.80 90.2 3.05 2.93 41.20 89.6
E. China m33 42.3 23.4 24.1 10.2 2.4 34.3 1.50 5.00 89.7 5.37 5.34 33.80 88.6
Qi eta l., 1995 m38 52.5 25.3 15.2 7.0 2.2 22.2 1.47 5.02 89.6 3.91 3.38 36.80 88.8
m31 57.6 20.2 15.2 7.0 2.2 22.2 1.51 4.99 89.7 3.54 3.23 37.90 89.1
m6 60.3 19.3 12.5 7.3 1.7 19.8 1.29 4.99 89.4 3.66 2.93 38.50 89.2
M8 64.0 21.0 12.0 2.0 6.0 14.0 1.51 5.18 90.0 2.15 2.6 40.36 89.9
M30 55.0 22.0 16.0 8.0 2.0 24.0 1.36 5.01 89.6 3.8 3.5 37.90 89.2
M22 44.0 32.0 14.0 10.0 1.4 24.0 1.37 5.07 89.7 4.61 3.35 36.10 89.0
M34 59.0 29.0 8.3 4.0 2.1 12.3 1.97 5.37 90.5 2.81 2.15 39.63 90.4
M35 53.0 26.0 10.0 11.0 0.9 21.0 1.43 5.11 89.8 4.43 2.78 37.48 89.1
M7 52.0 27.0 13.0 8.3 1.6 21.3 1.40 4.78 90.0 3.94 3.32 36.40 89.3
M32 61.0 20.0 10.0 7.5 1.3 17.5 1.86 5.34 90.5 3.35 2.75 39.20 90.1
X77 53.0 28.0 15.0 4.5 3.3 19.5 2.26 5.62 89.9 3.26 3.25 37.30 89.0
M3 63.0 13.1 14.1 9.7 1.5 23.8 1.27 5.07 89.7 2.93 3.03 39.15 88.1
MD-4 70.2 13.4 5.9 10.5 0.6 16.4 2.22 5.45 90.7 2.77 2.08 43.35 92.2
Liu & Fan, 1990 ZN-12 40.8 32.3 14.1 12.8 1.1 26.9 1.15 5.65 88.8 5.16 3.28 35.28 89.2
Fan& Hoope1r,9 89 MQ-8 44.5 29.4 17.9 8.2 2.2 26.1 1.53 5.37 89.9 4.8 3.66 36.11 89.9
Notes:B lanke ntries= nod ata;* averagefo r gntp eridotite(sN ixona ndB oyd,1 979)a ndS terne t al., (1989)