Provenance of the Gamburtsev Subglacial Mountains from U–Pb and Hf analysis of detrital zircons in...

Sedimentary Geology 211 (2008) 12–32

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Sedimentary Geology

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Provenance of the Gamburtsev Subglacial Mountains from U–Pb and Hf analysis ofdetrital zircons in Cretaceous to Quaternary sediments in Prydz Bay and beneath theAmery Ice Shelf

J.J. Veevers a,⁎, A. Saeed a, P.E. O'Brien b

a GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney NSW 2109, Australiab Geoscience Australia, GPO Box 378, Canberra 2904, Australia

⁎ Corresponding author. Tel.: +61 2 9850 8355; fax: +E-mail address: [email protected] (J.J. Veever

0037-0738/$ – see front matter © 2008 Elsevier B.V. Aldoi:10.1016/j.sedgeo.2008.08.003

a b s t r a c t
a r t i c l e i n f o
Article history:
In central Antarctica, drain Received 14 December 2007Received in revised form 25 July 2008Accepted 19 August 2008
Keywords:Detrital zirconsU–Pb agesHf-isotopesPrydz BayAmery Ice Shelf

age today and earlier back to the Paleozoic radiates from the GamburtsevSubglacial Mountains (GSM). Proximal to the GSM past the Permian–Triassic fluvial sandstones in the PrinceCharles Mountains (PCM) are Cretaceous, Eocene, and Pleistocene sediment in Prydz Bay (ODP741, 1166, and1167) and pre-Holocene sediment in AM04 beneath the Amery Ice Shelf. We analysed detrital zircons for U–Pb ages, Hf-isotope compositions, and trace elements to determine the age, rock type, source of the hostmagma, and “crustal” model age (TDMC ). These samples, together with others downslope from the GSM andthe Vostok Subglacial Highlands (VSH), define major clusters of detrital zircons interpreted as coming from(1) 700 to 460 Ma mafic granitoids and alkaline rock, εHf 9 to −28, signifying derivation 2.5 to 1.3 Ga fromfertile and recycled crust, and (2) 1200–900 Ma mafic granitoids and alkaline rock, εHf 11 to −28, signifyingderivation 1.8 to 1.3 Ga from fertile and recycled crust. Minor clusters extend to 3350 Ma. Similar detritalzircons in Permian–Triassic, Ordovician, Cambrian, and Neoproterozoic sandstones located along thePaleoPacific margin of East Antarctica and southeast Australia further downslope from central Antarcticareflect the upslope GSM–VSH nucleus of the central Antarctic provenance as a complex of 1200–900 Ma(Grenville) mafic granitoids and alkaline rocks and older rocks embedded in 700–460 Ma (Pan-Gondwana-land) fold belts. The wider central Antarctic provenance (CAP) is tentatively divided into a central sector withnegative εHf in its 1200–900 Ma rocks bounded on either side by positive εHf.The high ground of the GSM–VSH in the Permian and later to the present day is attributed to crustalshortening by far-field stress during the 320 Ma mid-Carboniferous collision of Gondwanaland and Laurussia.Earlier uplifts in the ∼500 Ma Cambrian possibly followed the 700–500 Ma assembly of Gondwanaland, andin the Neoproterozoic the 1000–900 Ma collisional events in the Eastern Ghats–Rayner Province at the end ofthe 1300–1000 Ma assembly of Rodinia.

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1. Introduction

The Gamburtsev Subglacial Mountains (GSM) of central Antarctica(Fig. 1) have intrigued investigators about their age and compositionsince their discovery in the 1950s by a Soviet seismic expedition.Dalziel (1992) wrote that “they are totally unknown geologically. Thedrainage basins of this [East Antarctic] ice sheet date back to thePermian, possibly to the Proterozoic.” Developing the idea of Permiandrainage, Tewari and Veevers (1993), Veevers (1994, 2000, p. 126)found that the present drainage of East Antarctica, with ice radiatingfrom a central Dome Argus (Fig. 1) draped over the high ground of theGSM, recapitulates the Early Permian scene, including the south polarlatitude. This ideawas recently tested by an analysis of detrital zircons

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from Early Permian sandstones in Dronning Maud Land (DML) andconjugate southeastern Africa (Veevers and Saeed, 2007), frommorainal clasts of Permian siltstone in the southern Prince CharlesMountains (PCM) (Veevers et al., 2008), and from Permian–Triassicsandstones in the northern PCM and ?Triassic sandstone in PrydzBay (PB) (Veevers and Saeed, 2008). Together with data from Indiaand eastern Australia, this evidence points to a central Antarcticprovenance (CAP), including the GSM and the Vostok SubglacialHighlands (VSH), of a complex of 1200–900 Ma (Grenville) cratonswith mafic granitoids embedded in 700–500 Ma fold belts withgranitoids and alkaline rocks. Neoproterozoic (970–650 Ma) meta-sedimentary rocks in the southern PCM downslope from the GSM(Phillips et al., 2005, 2006) suggest an even earlier inception of thedrainage from the CAP.

The higher ground of the GSM in the Permian and later isattributed to crustal shortening by far-field stress during the 320 Mamid-Carboniferous collision of Gondwanaland and Laurussia

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Fig. 1. Salient features of Prydz Bay (PB) (O'Brien et al., 2004, 2007) and hinterland (Veeversand Saeed, 2008) during the Quaternary. Shown in PB and its extension under the Amery IceShelf are the sites of core samples of Quaternary sediment (ODP 1167, AM04), the PrydzChannelFanoutlinedby the2600mand600misobaths, PrydzChanneloutlinedby the600misobath, post-early Pliocene pre-mid Pleistocene ice-flow patterns for extreme ice advances(arrows) (O'Brien et al., 2007,fig.. 7),flow lines of the Amery Ice Shelf/Lambert Glacier system,from radar interferometric studies (visibleearth.nasa.gov/view_rec.php?id=1618) augmentedby LANDSATstudies byHambrey (1991). Nunataks of Precambrian rock (black) and Permian–Triassic rock,marked by P, are fromVeevers and Saeed (2008). TheGSMandVSH are outlinedby the 2000-m contour, and set within the 500-m contour; Dome Argus is outlined by the4000-mcontour, and the subglacial Lambert drainagedivide (broken line) is from Jamieson etal. (2005; Stewart Jamieson, pers. comm., 2006). CM = Clemence Massif.

13J.J. Veevers et al. / Sedimentary Geology 211 (2008) 12–32

(Veevers, 1994). Earlier uplifts in (a) the Late Cambrian (∼500 Ma)could have followed the 650–500 Ma assembly of Gondwanaland,and in (b) the Neoproterozoic (950–650 Ma) followed the 1000–900 Ma collisional events in the Eastern Ghats–Rayner Province atthe end of the 1300–1000 Ma assembly of Rodinia (Rogers andSantosh, 2004).

Seen late in the preparation of this paper were the papers oncombined geochronology and thermochronology of single detritalzircons, apatites, and hornblendes from PB sediment derived from theGamburtsev Subglacial Mountains. Cox et al. (2007), Hemming et al.(2007), and van de Flierdt et al. (2007) find geochronological peaks of550–500 Ma and 1050–850 Ma (confirmed in this work), and, fromcombined zircon and apatite (U–Th)/He cooling models, slow coolingsince about 500 Ma with erosion rates of 0.03 km/Ma or less.

Our study of detrital zircons from Holocene sand in AM04 beneaththe Amery Ice Shelf, Pleistocene sand in ODP 1167A, Eocene sand inODP 1166A, and Early Cretaceous sand in ODP 741A, all within thepresent Lambert drainage system, traces the evolution of the GSM–

VSH and CAP since the Permian–Triassic. Through studying the U–Pb,Hf and trace element compositions of these detrital zircons,considerable insight into the age and composition of central EastAntarctica can be made.

1.1. Setting

Ice in the Lambert Glacier and Amery Ice Shelf (Fig. 1) flowsthrough the Lambert Graben from Dome Argus. The path of ice flow isfrom the GSM past Komsomolskiy Peak, between the southern PCMand the Mawson Escarpment (Fig. 2), past the Clemence Massif (CM),and finally between theMunro KerrMountains and the northern PCM.Ice flow from the sides is minor.

According to ice-flow data (Fig. 1), the sand in AM04 comes fromice that flowed from the south. During extreme ice advances in theearly Pleistocene, the main ice flow NNE through the Lambert Graben(Fig. 2) was deflected by ice from the Ingrid Christensen Coast (arrowsin Fig. 1) to the west to flow along the Prydz Channel and terminateabove the Prydz Channel Fan. Sediment carried in this ice also camefrom the south.

In pre-glacial times, the Eocene fluvial sediment in ODP 1166 andEarly Cretaceous (Albian) sediment in ODP 741 were deposited withinthe eastern branch of the Lambert Graben (Fig. 2) but without anyclear paleocurrent indicators.

Full details of the sands fromwhich the zircons were extracted aregiven below.

1.2. Age and composition of bedrock of the PCM–PB region

The geological neighbourhood north of the GSM is now relativelywell known (Fig. 2), at least in terms of ages, thanks to the geologicalstudies of the PCM (Mikhalsky et al., 2001; Boger et al., 2006, 2008), thedescription of the lithostratigraphic groups in the southern PCM(Phillips et al., 2005) and their U–Pb geochronology involving ∼1500detrital zircons (Phillips et al., 2006), and geological studies bynumerous authors, including Carson et al. (1996) and Wilson et al.(2007), of the region around PB. All these data are compiled in Veeversand Saeed (inpress). The age and compositionof Precambrianbedrock isaugmented by a U–Pb and TDM geochronological and host-rock study ofseveral hundreddetrital zircons in the Permian–Triassic AmeryGroup inthenorthernPCMand in ?Triassic sandstone inODP 740A in PB (Veeversand Saeed, 2008).

2. Methods of analysis, presentation, and interpretation of data

Details of the methods are given in the appendix: SupplementaryData in the online version. In brief, the samples were processed bystandard methods for separating zircons. Zircons were imaged by

Fig. 2. MacRobertson Land, Princess Elizabeth Land, and Prydz Bay geology after Fitzsimons (2003, fig.. 5) and Mikhalsky et al. (2001), and modified from Veevers and Saeed (2008),showing location of ODP 741 with Cretaceous sediment, ODP 1166 with Eocene sediment, ODP1167 with Pleistocene sediment, and AM04 with pre-Holocene sediment. ODP 740A,with ?Triassic sediment (Veevers and Saeed, 2008) is also shown. Lambert Graben, from Golynsky et al. (2006), is interpolated (broken line) between 70°S and the western edge of apositive feature (tiny circles indicate boundaries on seismic lines, Stagg, 1985; Cooper et al., 1991a, Fig. 2-1). Structures west of the Svenner Channel and bathymetry are from Stagg(1985). Outcrop of Precambrian rock marked in black within terranes (patterns) with names in bold, TDMNd (Ga) is encircled. Alkaline rocks aremarked by an asterisk, with age in Ma.The leaf symbol indicates the Permian–Triassic Amery Group at Beaver Lake and Mt Meredith, and the Glossopteris-bearing red siltstone in moraine at Mt Rymill and Mt Maguire inthe southern PCM, carried in the ice northward (arrow) an unknown distance. The quartzite at Komsomolskiy Peak, with detrital zircons aged 2600 Ma, 2000 Ma, and 1850 Ma, wasdeposited after 1850 Ma (Phillips et al., 2006).

14 J.J. Veevers et al. / Sedimentary Geology 211 (2008) 12–32

cathodoluminescence and back-scattered electron methods to deter-mine internal structure. Images of typical grains of the populations aregiven in Fig. 10.

U–Pb analysis of individual grains of zircon was conducted bylaser-ablation microprobe inductively coupled plasma-mass spectro-metry (LA-ICPMS) and Hf-isotope analysis (εHf and TDM

C model age) by

Fig. 3. AM04 core log. The zircons were extracted from a sample of the sand and gravelunit 74–123 cm.

Fig. 4. Detrital zircons (sample AM04) from pre-Holocene sediment beneath the Amery Ice Shewide bins of a pooled sample of 60b20% (52b5%) discordant grains, with main peaks at 536Maages of low-HREE-c zircons are shown above. Probability distribution diagramof TDMC ages (Ga) orange 960-900 Ma are dominated by mafic (b65% SiO2) granitoids, have positive and negativeolder crustal sources; those in the range 560–500 Ma, also dominated by mafic granitoids anarrows) from older crustal sources. (b) histograms of rock types of 9 grains within the 500–5665=granitoid with b65% SiO2, M = mafic rock, L = low-HREE-c rock. (c) εHf versus ages of 50 zi


laser-ablation-multi-collector inductively coupled plasma-mass spec-trometry (LA-MC-ICPMS).

We use the more precise 206Pb/238U ages for grains with 207Pb/206Pbagesb1000 Ma and 207Pb/206Pb ages for older grains (Gehrels et al.,2006). TheU–Pb ages have aprecision of±1%or less comparable to thoseof ion-probe data. We cite peaks in age probability in single numerals,e.g., 1007 Ma, but the precision of ±1% is implicit.

We followGillis et al. (2005) in admitting grains≤20% discordant. Acommon value for 1 sigma uncertainty based on random ormeasurement errors is ∼10Ma.We follow Gehrels (2006) and Gehrelset al. (2006) in “the view that only clusters of ages record robustsources ages, and attach significance only to age peaks that comprisethree or more analyses”. The data are presented in age probabilityplots with histograms (Ludwig, 2001) that show the number ofanalyses within each 20 million-year interval. Further information oninterpretation is given in Link et al. (2005).

Trace-element abundances in zircon were determined by electronmicroprobe and ICPMS analysis. Belousova et al.'s (2002) classificationand regression tree (CART) of zircons has a branch interpreted ascoming from alkaline rocks and carbonatites (ARCs), with thesediscriminates: Lub20.7 ppm and Tab0.5 ppm characterize syenite;Lub20.7 ppm, TaN0.5 ppm, then LuN2.3 ppm characterize carbona-tite. In place of the inferred rock-type names, we refer to zircon grainswith these characteristics by the general descriptive term “low heavy-rare-earth-element (low-HREE) group”. We discriminate further by“low-HREE-c” for those classified as carbonatite.

The analytical data of the 8 samples are available in archived Excelfiles AM04, ODP 741A, ODP 1166AU, ODP 1166AL, ODP 1167A-19, ODP

lf. (a) U–Pb ages in a probability distribution diagram and histogramwith 20 million-yearand 936 Ma; significant (nN3) clusters (grey bars) are 960–900Ma and 560–500 Ma; the

f 47 grainsb2500Ma and TDM ages of 3 grainsN2500Ma,with a peak at 1.9Ga; grains in theεHf , signifying derivation at TDMC =1.7 Ga (dashed arrows) from mixed juvenile mantle andd including 2 low-HREE-c, have negative εHf signifying derivation at TDMC =1.9 Ga (dashed0 Ma range and 14 within 960–900 Ma. Rock types are: 75=granitoid with 70–75% SiO2,rcons with trace-element classification of rock types.

Table 1Sample pooled from cores in ODP 1167A (O'Brien et al., 2001)

Core mbsf Clasts

19 150.55–155.52 quartzite, dolerite, metamorphic rock, granite, coal22 179.76–180.68 sandstone, quartzite, coal37 322.80–326.37 garnet-bearing quartzite39 341.85–343.80 –

mbsf = metres below seafloor.


1167A-22, ODP 1167A-37, ODP 1167A-39 in the Appendix: Supplemen-tary data, in the online version.

3. Holocene sand in AM04

3.1. Setting

Core AM04 is a short gravity core collected from beneath the AmeryIce Shelf throughahot-waterdrill-hole locatedat 69.90°S70.29°E,120kmfrom its edge (Fig. 1) at a surface elevation of 71.0 m asl atop the 603-m-thick ice shelf and 399mof seawater to the seafloor at 931mbsl. It is oneof a set of 4 such cores collected by the Australian Antarctic Division(Craven et al., 2004, 2006; Hemer et al., 2007). The core (Fig. 3) comprisesan upper 74 cm thick unit of clayey silt formed by hemipelagic settlingbeneath the ice shelf and a lower unit 49 cm thick (to total depth) of sandandgravel formednear the ice shelf groundingzonebycurrentsproducedby thermohaline circulation and tidal pumping (Hemer et al., 2007).

The detrital zircons analysed in this study come from the lower unit.Its deposition close to the former grounding zone beneath the ice shelfmeans that the detritus was exclusively derived from transport in basalicewith no likelihood of debris transported by icebergs and only a smallchance of material coming from the north via sub-ice shelf currents.Examination of satellite imagery places the core location on a flow lineoriginating from the south-western and southern tributary glaciers ofthe Amery Ice Shelf, most likely the Collins and Mellor Glaciers (Fig. 1).The sample therefore represents the provenance of the modernGamburtsev Subglacial Mountains.

Fig. 5. ODP 1167A stratigraphical column showing the distribution of the four samples, the deO'Brien et al. (2007). IRD = ice-rafted debris.

The debris assemblage represents subglacial material released atthe grounding line. Its equivalent material in ODP Site 1167A is themuddy sand with dispersed pebbles found deeper than 5.17 m belowsea floor (mbsf) (Fig. 5). These sediments were also derived from theglacier grounding zone when it was at the shelf edge (Passchier et al.,2003; O'Brien et al., 2007). The material shallower than 5.17 mbsf insite 1167A probably has ice-rafted and hemipelagic components.

3.2. Age profiles and host rock types

The U–Pb ages (Fig. 4) are clustered between 960 Ma and 900 Maabout apeakat936Ma, andbetween560Maand500Maabout apeakat536 Ma, with an isolated peak at 1056 Ma, and a scattering of ages to3300 Ma. The TDM

C model ages peak at 1.9 Ga within a range of 2.2–1.6 Ma. The host rocks are interpreted as dominantly mafic granitoids,with 3 grains (aged 2138, 530, 517 Ma) from low-HREE-c hosts. εHfvalues are distributed as follows: (1) most 960–900 Ma zircons, withpositive or near positive εHf, come from juvenilemantle sources derivedfrom the mantle at 1.7 Ga; (2) the 560–500 Ma zircons, with negativeεHf, come from the reworking of older crust generated from thedepleted mantle at 1.9 Ga.

Within 150 km of the 530 and 517 Ma low-HREE-c zircons in AM04are the 524 Ma and 500 Ma A-type granites of Jetty Peninsula andLanding Bluff, on either side of the Amery Ice Shelf (Fig. 2). Close by the∼936 Ma and 1.9–1.7 Ga TDM

C zircons are the 1000–900 Ma and 2.2–1.8 Ga TDM granitoids and gneisses of the Beaver Terrane. Accordingly,these areas are potential provenances of the AM04 zircons, but, as weshow below, the directions of paleoflow of the deposits indicate themain provenance in the south in the GSM.

4. Pleistocene sand in ODP 1167A

4.1. Setting

ODP 1167Awas sited at 66.40°S 72.28°E in awater depth of 1640mon the upper slope to penetrate the Pleistocene Prydz trough-mouth

positional environment, and the dominant provenance. From Passchier et al. (2003) and


fan (O'Brien et al., 2001; Cooper and O'Brien, 2004). We chose samplesfrom the sand layers in four cores (Table 1).

As shown in Fig. 5, the samples comprise gravel and coarse sand ofFacies II, debris-flow deposits (O'Brien et al., 2001). Passchier et al.(2003) distinguish Lithofacies IIB (84–217 mbsf), debris (gravity)-flowdeposits, including clast-rich debrites and lag deposits with bottom-current deposits and hemipelagic muds with ice-rafted debris (IRD),and IIC, debris-flow deposits with horizontal clast fabric indicatinglaminar flow, and few glaciomarine and hemipelagic sediments. Allsamples are Pleistocene: cores 19 and 22 are bracketed by ages of0.78 Ma and 1.13 (+0.2/−0.45) Ma, and cores 37 and 39 are older than1.13 (+0.2/−0.45) Ma.

According to Passchier et al. (2003) and O'Brien et al. (2007), thesuccession of debris flows in ODP 1167A came from over-steepenedupper-slope sediment deposited frommelt-out at the grounding zone

Fig. 6. Zircons (samples 1167A −19, 22, 37, 39) from the Pleistocene of PB. (a) U–Pb ages in pr(b) U–Pb ages in probability distribution diagrams and histograms with 20 million-year wide516 Ma and significant (nN3) clusters (shaded) of 1100–760 Ma, 640–540 Ma, and 540–480 M1933 Ma. Probability distribution diagram of TDMC ages of 191 grainsb2500 Ma and TDM agewithin the 480-540 Ma range, 24 within 540–640 Ma, and 54 within 760–1100 Ma. Rock typelow-HREE-c rock. (d) εHf versus ages of 195 zircons with trace-element classification of rock

at the continentnal shelf edge of the Amery Ice Shelf duringmaximumice advance. In the early Pleistocene (N1 Ma), during the deposition ofUnit IIC, including samples 1167A-37 and -39, “increased ice volumesproduce grounding of the ice and erosion of graben sediments …

Maximum ice volumes produce maximum depth of erosion and hencethe largest component of recycled sedimentary basin detritus in thesediment load” (O'Brien et al., 2007, p. 401), evidenced by dominantcoaly organic matter, finer-grained magnetic minerals, and smectites,from Permian sediments of the Lambert Graben. The main ice flow atthis time (Fig. 1) was NNE through the Lambert Graben and thendeflected by ice from the Ingrid Christensen Coast to the west formingthe Prydz Channel and the Prydz Channel Fan. In the mid to latePleistocene (b1 Ma) (Unit IIB, samples 1167A-19 and -22), “lowermaximum ice volume will not erode so deeply so that a blanket ofbasement-derived detritus may protect the basin fill from erosion,

obability distribution diagrams from the four samples arranged in stratigraphical order.bins of a pooled sample of 224b20% (mostb5%) discordant grains, with a main peak ata; the ages of 25 low-HREE-c grains cluster at 520, 790, and 930 Ma, and the oldest is ats of 7 grainsN2500 Ma, with a peak at 2.1 Ga. (c) histograms of rock types of 93 grainss are: 75=granitoid with 70–75% SiO2, 65=granitoid withb65% SiO2, M =mafic rock, L =types.

Fig. 7.ODP 1166A stratigraphical column showing the distribution of the samples (cores18-22, 24-28), and the depositional environment. From Cooper and O'Brien (2004).Plio=Pliocene; Ol=Oligocene; Eo=Eocene.

Table 2Sample pooled from cores in ODP 1166A (Cooper and O'Brien, 2004)

Core mbsf Lithology

18–19 (U = upper) 161.0–180.3 massive coarse grey sand and sandstone withgranules and rare pebbles

22 (U) 199.5–209.1 matrix-supported very coarse sand withgranules and pebbles

24–28 (L = lower) 218.7–266.8 matrix-supported very coarse sand with granulesand pebbles with fibrous black organic fragments



resulting in a reduced sedimentary signal in downstream glacialdeposits”, evidenced by dominant basement lithologies (granite,metamorphics, illite, quartz, felspar). Lower ice volume reduced theice advance across the shelf so that today gravity flow at the shelf edgeis minor. The reduced sedimentary signal in downstream depositsmeans that Precambrian basement was the dominant provenance ofUnit IIB.

Because the zircons can be traced through ice flow to the southernprovenance, their properties reflect the GSM during the Pleistocene.

4.2. Pooled sample from cores 19, 22, 37, 39

The distribution of U–Pb ages of the detrital zircons of theindividual samples is essentially the same with clusters within 480–640 Ma and 760-1100 Ma (Fig. 6a). The distribution of TDM ages, hostrocks, and εHf is also the same. Accordingly, all four samples arepooled to provide the most information (Fig. 6b, c, d).

Because the detrital zircons of the pooled samples 1167A-37+39and 1167A-19+22 have the same U–Pb and TDM ages, host rocks, andεHf distribution, this suggests (a) that the detrital zircons do notregister the early Pleistocene to mid-late Pleistocene change inproximal provenance indicated by ice-flow patterns and the composi-tion of debris (O'Brien et al., 2007), and (b) that the recycled zirconsfrom the Amery Group are indistinguishable from those deriveddirectly from the older provenance.

In the pooled sample (Fig. 6b, c, d), U–Pb ages peak at 516 Mawithin a significant (nN3) cluster (shaded) of 540–480 Ma; minorclusters are from 640–540 Ma and 1100–760 Ma. TDMC ages have amajor peak at 2.1 Ga and a minor one at 1.4 Ga within a range of 2.5–1.2 Ga. Grains in the range 540–480 Ma are mainly from maficgranitoids and include 11 low-HREE-c hosts; they have mainlynegative εHf signifying derivation at TDM

C =2.1 Ga from older crustalsources. Zircons in the range 640–540 Ma are also mainly from maficgranitoids; they have positive and negative εHf, signifying derivationfrom mixed juvenile mantle and older crustal sources. Zircons in therange 1100-760Ma aremainly from granitoids and include low-HREE-c hosts concentrated at 930 and 790 Ma; they have positive andnegative εHf, signifying derivation at TDMC =1.8 Ga from mixed juvenilemantle and older crustal sources.

5. Eocene sand in ODP 1166A

5.1. Setting

ODP 1166A was sited at 67.70°S 74.79°E in a water depth of 475 mon the continental shelf, and penetrated Unit III of middle-late Eocenealluvial to deltaic matrix-supported sandstone (Fig. 7)(Cooper et al.,2001; O'Brien et al., 2001; Cooper and O'Brien, 2004). We chosesamples from sand in four cores (Table 2).

A middle-late Eocene (39–34 Ma) age is indicated by pollen of themiddle Nothofagidites asperus palynozone (Macphail and Truswell,2004). Most of Unit III was deposited in fluvial channels and also inflood or tidal basins or lagoons (Cooper and O'Brien, 2004). The PBcoastal plain was covered by a low-growing scrub of gymnospermsand angiosperms (Nothofagus) that suggest humid conditions andprobably low temperatures at sea level (Macphail and Truswell, 2004).Evidence for nearby glaciation in the rift-flank mountains to the southis seen in sand grain surface features in the middle-late Eocene sands(Strand et al., 2003). Clear evidence of glaciation is found in theoverlying early Oligocene marine sediments with lonestones followedby till.

5.2. Pooled sample 1166A-U+L

Wechose a sample each fromcores 18–22 (U=Upper) and24–28 (L =Lower) (Table 2). Because the age profiles of the samples (Fig. 8a) lacksignificant differences, we pooled the samples to provide the mostinformation. U–Pb ages (Fig. 8b) peak at 528 Ma within a significantcluster (shaded) of 620–500 Ma; minor clusters are 740–640 Ma and1000–840Ma. TDMC ages are in the range of 2.8–1.0 Ga peak at 2.1 Ga, anda shoulder at 1.6 Ga. Grains in the range 620–500 Ma are mainly frommafic granitoids, and include 11 low-HREE-c hosts; they have mainlynegative εHf signifying derivation at TDM

C =2.0 Ga from older crustalsources. Zircons in the range 740–640 Ma are mainly from maficgranitoids and mafic rocks; they have positive εHf, signifying derivationat TDMC =1.5 Ga from juvenile mantle sources. Zircons in the range 1000–840 Ma are mainly from mafic granitoids and mafic rocks, and includelow-HREE-c hosts at 958 and 851 Ma; they have positive and negativeεHf, signifying derivation at TDMC =1.7 Ga frommixed juvenilemantle andolder crustal sources.

The zircons from1166A (Fig.11d) resemble those inAM04 and 1167A(Fig. 11a, b), which, as we show below, came from the south. It followsthat 1166A probably came from the same provenance in the south.

6. Early Cretaceous (Albian) sand in ODP 741A

6.1. Setting

ODP 741A was sited at 68.39°S 76.38°E in a water depth of 551 m,30 km seaward of the fault scarp (Cooper et al., 1991b) beneath theSvenner Channel at the edge of a 120-km-wide and 8-km-deep graben(Cooper et al., 1991a, fig.. 2-1). ODP 741 is overlooked by the Archeanand Proterozoic rocks of the Vestfold Hills and Rauer Group, and 550–

Fig. 8. Zircons (pooled samples 1166AU and 1166AL=1166A-U + L) from the Eocene of PB. (a) U–Pb ages in probability distribution diagrams from the two samples arranged instratigraphical order. (b) U–Pb ages in probability distribution diagrams and histograms with 20 million-year wide bins of a pooled sample of 116b20% (96b5%) discordant grains,with a main peak at 528 Ma and significant (nN3) clusters (shaded) of 1000–840 Ma, 740–640 Ma, and 620-500 Ma; the ages of 13 low-HREE-c zircons are shown above, with 11 at528 Ma, and singles at 851 and 958 Ma. Probability distribution diagram of TDMC ages (Ga) of 94 grainsb2500 Ma and TDM ages of 8 grainsN2500 Ma, with a peak at 2.1 Ga and ashoulder at 1.6 Ga; grains in the range 1000-840 Ma are dominated by mafic granitoids, have positive and negative εHf , signifying derivation at TDMC =1.7 Ga from mixed juvenilemantle and older crustal sources; those in the range 620–500 Ma, also dominated by mafic granitoids and including 11 low-HREE-c, have mainly negative εHf signifying derivation atTDMC =2.0 Ga from older crustal sources. (c) histograms of rock types of 48 grains within the 500–620 Ma range, 7 within 640–740 Ma, and 21 within 840–1000 Ma. Rock types are:

75=granitoid with 70–75% SiO2, 65=granitoid withb65% SiO2, M = mafic rock, L = low-HREE-c rock. (d) εHf versus ages of 100 zircons with trace-element classification of rock types.


500 Ma syenogranite of the Larsemann Hills (Fig. 2). We chosesamples from the sand layers in four cores (Table 3).

ODP 741A penetrated a 100-m-thick succession of Early Cretaceousfluvio-lacustrine coal-bearing sediment, part of Unit IV of Turner and

Padley (1991). Palynomorphs indicate the Coptospora paradoxa Zoneof middle to late Albian (105–100 Ma) age (Truswell, 1991; Truswellet al., 1999). The sediments form the upper part of a 2- to 3-km-thicksubhorizontal sedimentary succession.

Table 3Sample pooled from cores in ODP 741A (Barron et al., 1989)

Core mbsf Lithology

4 23.9–33.5 dark grey bioturbated sandstone with granules andfragments of coal

6 43.2–52.9 dark grey bioturbated sandstone with granules andfragments of coal

12, 13 101.2–120.5 dark grey sandstone with fibrous black organic fragments



6.2. Pooled sample 741A

We pooled a sample from the sandstone intervals of cores 4, 6, 12,and 13 between 25.57 mbsf and 111.68 mbsf (Table 3). U–Pb ages(Fig. 9) peak at 536 Ma within the only significant (nN3) cluster(shaded) of 580–520 Ma. TDMC ages peak at 2.2 Ga within a range of2.5–1.8 Ga. Grains are mainly from mafic granitoids, and include 12low-HREE-c hosts. All but one have negative εHf signifying derivationat TDMC =2.1 Ga from older crustal sources.

Of the samples analysed here, 741A is unique in lacking asignificant number of grains in the 1100–800 Ma interval and older.Notably absent are any zircons from the nearby Archean andProterozoic Vestfold Hills and Rauer Group, which, in the Albian,were evidently bypassed in favour of the more distant 550–500 Maalkaline rocks of the Larsemann Hills and Landing Bluff (Fig. 2), orequivalents elsewhere.

Fig. 9. Zircons (sample 741A) from the Early Cretaceous (Albian) of PB. (a) U–Pb ages in a prob56b10% (52b5%) discordant grains, with peak at 536Ma; all but 3 are significantly (nN3) clusProbability distribution diagram of TDMC ages (Ga) of 50 grainsb2500 Ma, with a peak at 2.2have negative εHf signifying derivation at TDMC =2.1 Ga from older crustal sources. (b) histogrmafic rock, L= low-HREE-c rock. (c) εHf versus ages of 46 zircons with trace-element classifi

7. Morphology and host rocks of the zircons

Zircons from the four localities have similar morphology andstructure (Fig. 10, Table 4). They range in shape from rounded toeuhedral, equant to elongate, in structure from structureless tooscillatory zoning, and in size from 50–300 µm (rarely 30–600 µm).Most of the low-HREE-c zircons are structureless, the same as those inSE Africa/Dronning Maud Land and in the ?Triassic of PB (Veevers andSaeed, 2007, 2008).

In their study of quartz grainmicrotextures for the onset of Eocene/Oligocene glaciation in ODP 1166, Strand et al. (2003) found thehighest frequency of grains with round edges in the Eocene sands, asfound here in the grains of zircon. Other quartz grains with angularoutlines, conchoidal fractures, and crescentic gouges were interpretedas indicating a distal glacial source at the onset of Antarctic glaciation.

8. Synthesis

8.1. Comparison of detrital zircons

The four sets of zircons described above together with those fromthe nearby ?Triassic red beds of ODP 740A and the Permian–TriassicAmery Group (Veevers and Saeed, 2008) are summarized in Table 5and shown, with bedrock age profiles shown in Fig. 11c, g. Paleoflowdata indicate that the Quaternary AM04 and 1167A (a, b) andPermian–Triassic Amery Group (h) have their major provenance inthe south in the GSM, withminor provenance in the immediate regionof the PCM and PB (c, g).

ability distribution diagram and histogramwith 20million-year wide bins of a sample oftered (shaded) in the range 580–520Ma, including 12 low-HREE-c zircons, shown above.Ga; grains are dominated by mafic granitoids and low-HREE-c hosts, and all except oneams of rock types: 75=granitoid with 70–75% SiO2, 65=granitoid with b65% SiO2, M =cation of rock types.

Fig. 10. Back-scattered electron (BSE) – cathodoluminescence (CL) images of selected zircon grains from the age main clusters (650–500 Ma, 1100–800 Ma). The smaller circle locatesthe U–Pb laser ablation pit∼30 µmwide, the larger circle the Hf-isotope pit∼50 µmwide. In each frame are shown the scale bar, the grain number, U–Pb age, and the host rock type.


In terms of U–Pb ages, all (including bedrock) contain a major 650–500 Ma cluster (shading), which includes low-HREE-c hosts, and,except 741A, an 1100–800 Ma cluster, including three with low-HREE-c hosts. In terms of TDM

C model ages, within a range of 2.4–1.7 Ga(horizontal pattern), four have peaks ∼2.1 Ga and another at 1.9 Ga;the sixth has a peak of 1.45 Ga within a range of 1.7–1.2 Ga (verticalpattern), which includes the shoulders of three samples. All except741A contain TDM ages 3.7–2.8 Ga (shading).

The similar Eocene (1166A), Pleistocene (1167A), and pre-Holocene(AM04) samples reflect two sets of rocks (Fig. 11, Table 5): (1) 640-(mean 527)-480 Ma mafic granitoids and minor low-HREE-c hosts,with TDMc∼2.0 Ga, and derivation mainly from older crustal sources(εHf 8 to −32), and (2) 1100-(935)-760 Ma mafic granitoids and minorlow-HREE-c hosts, with TDMc 1.75 Ga, and derivation from mixedjuvenile mantle and older crustal sources (εHf 11 to −22).

Sample AM04 differs from the near-identical 1167A and 1166A byits prominent peak at 936 Ma without low-HREE-c hosts, and by ayounger peak of TDMc (1.9 Ga vs 2.1 Ga).

Table 4Properties of the zircons

Sampleno.

Properties

AM04 50–200 µm broken rounded, subhedral, euhedral; structureless, oscillatoryzoning

1167A-19 50–250 µm broken rounded subhedral; structureless, oscillatory zoning1167A-22 50–150 µm rounded, euhedral, subhedral, equant, elongate, structureless,

oscillatory zoning1167A-37 30–600 µm rounded euhedral, subhedral, equant, elongate, structureless,

oscillatory zoning1167A-39 50–200 µm rounded euhedral, subhedral, equant, elongate, structureless,

oscillatory zoning1166AU 50–250 µm rounded, euhedral, subhedral, oscillatory, diffusive, laminar

zoning, structureless1166AL 50–300 µm rounded, euhedral, subhedral, oscillatory, diffusive, laminar

zoning, structureless741A 50–300 µm rounded, euhedral, subhedral, oscillatory, diffusive zoning,

structureless

The Albian sample 741A contains the younger cluster only, with580-(536)-520 Ma mafic granitoids and minor low-HREE-c hosts, andderivation at TDMc 2.1 Ga mainly from older crustal sources (εHf,except one at +2, −4 to −19). The only other grains are two at ∼800Maand a single one ∼1000 Ma.

The next older sample, ?Triassic 740A, contains zircons thatvariously resemble those of the younger samples, and closest to1167A: prominent peaks at 910 Ma and 540 Ma, each dominated(exceptionally) by low-HREE-c hosts, derived mainly in the ∼910 Macluster (also exceptionally) from older crustal sources (εHf 3 to −28).740A is further exceptional in containing a significant number of∼3200 Ma zircons.

The oldest sample, the Permian–Triassic Amery Group, containszircons that resemble those of the others,with thesenotable exceptions:(1) its 534 Ma peak has positive to negative εHf (9 to −28), four of theothers have εHfb2; (2) TDMc peaks at 1.45 Ga, some 0.5 Ga younger thanthe others' peaks.

The properties of the samples independently shown to have beenderived mainly from the south — the Quaternary AM04 and 1167A(Fig. 13b, c), the Permian–Triassic Amery Group (d), the Neoproter-ozoic Sodrudhestvo Group (e), the Permian siltstone at Mt Rymill andMt Maguire (f) — are added to those of other samples with paleoflowindicators (Fig. 13a, h). The set of north-flowing sediment through theLambert Graben is now known to include the Quaternary AM04 and1167A (Fig. 13b, c), the Permian–Triassic Amery Group (d), the clasts ofPermian siltstone at Mt Rymill and Mt Maguire (f), and theNeoproterozoic Sodrudhestvo Group (e) in recording the high groundof the GSM. Additionally, the sand inclusion (f) in the ice of the LakeVostok drill-hole 5G-1 (Leitchenkov et al., 2007) is seen from ice flowto have come from the VSH.

8.2. Comparison with regional bedrock

U–Pb and TDM ages of bedrock in the PCM (west of 70°E) and in thePB coast and hinterland (east of 70°E) (Fig.11c, g) are fromVeevers andSaeed (2008). Both regions contain 650–500 Ma and 1100-800 Ma

Table 5Properties of samples AM04, 1167A, 1166A and 741A, and, from Veevers and Saeed (in press), of the ?Triassic succession in ODP 740A and the Permian–Triassic Amery Group by 650–500 Ma and 1200–900 Ma clusters, with peak TDMc in the far column

Range 650–(peak) 500 Ma

Rock type MainderivationTDMc Ga

εHf Range 1100–(peak) 800 Ma

Rock type MainderivationTDMc Ga

εHf PeakTDMc Ga

AM04 pre-Holocene 0 Ma 560 (536) 500 mafic granitoidlow-HREE-c

1.9 negative 0 to −12 960 (936) 900 mafic granitoid 1.7 positive–negative11 to −2

1.7

1067A Pleistocene 0–2 Ma 640 (516) 480 mafic granitoidlow-HREE-c

2.1 mainly negative 8to −32

1100 (940)(820) 760

granitoids low-HREE-c

1.8 positive–negative11 to −12

2.1

1066A Eocene 39–34 Ma 620 (528) 500 mafic granitoidlow-HREE-c

2.0 mainly negative 2to -26

1000 (928)(856) 840

mafic granitoidlow-HREE-c

1.7 positive–negative11 to −22

2.1

741A Albian 100 Ma 580 (536) 520 mafic granitoidlow-HREE-c

2.1 mainly negative2, −4 to −19

– – – 2.2

740A ?Triassic ?220 Ma 650 (540) 500 low-HREE-c 2.2 negative 0 to −33 1200 (1076,910) 800

low-HREE-cb65%granitoid

2.1–2.0 mainly negative 3to −28

2.15

Amery Gp Permian–Triassic 265–200 Ma

650 (639, 534) 500 granitoidslow-HREE-c

2.5–1.3 positive–negative9 to −28

1100 (919) 800 felsic granitoidmafic rock

1.8–1.5 positive–negative10 to −28

1.45

Under “rock type”, we cite the dominant type and the presence of low-HREE-c hosts.


rocks, mainly granitoids and metamorphic rocks, and minor alkalinerocks, in strong correlation with the detrital zircons. The only othercluster of U–Pb ages of detrital zircons is 3600–3200 Ma in sample740A, with a few grains of this age in AM04, 1166A, and the AmeryGroup. In comparison, this range of ages is found in a 3269 Ma gneissprotolith in the nearby Rauer Group on the eastern coast of PB (Kinnyet al., 1993).

In the bedrock west of 70°E, TDM Nd model ages are concentratedbetween 1.2 Ga and 0.9 Ga in the 500–50 Ma alkaline rocks of theBeaver Terrane, 2.2 and 1.7 Ga, and minor ones between 3.5 Ga and3.0 Ga. The 2.2–1.7 Ga concentration matches the 2.1 Ga and 1.9 Gapeaks in TDM

C in all the detrital zircons in Fig. 11 except the AmeryGroup's peak of 1.45 Ga.

In the bedrock east of 70 °E, TDM model ages are concentratedbetween 2.2 and 1.2 Ga, and minor ones 3.0–2.7 Ga and 0.7 Ga. The2.2–1.2 Ga concentration matches the young part of the 2.1 Ga peak,and encompasses the 1.45 Ga peak of the Amery Group.

In summary, in terms of U–Pb ages and TDM model ages, thebedrock either side of 70°E serves equally as a potential provenance ofthe detrital zircons in all the samples except 741A, which lackssignificant numbers of zircons older than 580 Ma. We infer that 741Acame exclusively from a ∼550 Ma provenance of alkaline rocks, thenearest of which are the 550–500 Ma syenogranite of the LarsemannHills and 500 Ma A-type granite of Landing Bluff (Fig. 2).

The general finding, that the zircons could have come from localbedrock on either side of 70°E or both, can be narrowed by consideringthe overriding constraint of paleoslope indicators.

8.3. Constraints from paleoslope indicators

Paleoslope indicators – ice and water flow vectors radiating fromcentral Antarctica – are shown on the map of the Early PermianGondwanaland platform (Fig. 12). The indicators relate to zircon datafrom rocks and sediments from the Neoproterozoic, Permian–Triassic,Triassic, and Quaternary, as summarized in Fig. 13. The boxed datafrom detrital zircons in the Lambert and Lake Vostok regions indicatethe age and composition of the upslope provenance in the GSM–VSH,and with other downslope data from SE Australia and DML(differences shown in square brackets) define a wider CentralAntarctic Provenance (CAP).

Of the eight downslope samples shown in Fig. 13, all but theHawkesbury Sandstone (a) and the Cambrian sediments of theEllsworth–Whitmore Mountains (g) and Amelang Plateau Formationof Dronning Maud Land (h) are close to the front of the GSM in theLambert Graben, from 200 km for Mt Maguire to 1200 km for 1167A,and one is on the side of the VSH (Fig. 1). Other downslope indicators

for samples with 700–500 Ma and 1200–1000 Ma zircons (butwithout host rock type data or TDM model ages) are shown (doublearrows) for Cambrian and Ordovician sediments in SE Australia andthe Transantarctic Mountains. Unlabelled single arrows refer toPermian sediments. TDMC model ages and εHf values are given for theCambrian sediment of Mt Welch and the Ellsworth–WhitmoreMountains Block (EWMB)(Fig. 13g).

The zircon ages are clustered (stipple) in order of increasingfrequency: 3350–3050 Ma, 2900–2600 Ma, 2300–1950 Ma, 1200-1000-900, 850–750 Ma, and 700–460 Ma, all of which are looselycorrelated with the letter symbols d+ to aaaa of Veevers et al. (2006).The occurrence of 4 of the 6 clusters in the proximal Glossopterissiltstone and in 3 clusters in the proximal Sodruzhestvo Groupsuggests that all 6 clusters reflect ages in the GSM.

The main 700–460 Ma cluster, recognised as d+, has theseproperties in the 5 analysed samples (a, b, c, d, h): (1) major rocktype hosts are mafic granitoids, dominant in 2 samples. (2) the minorrock type in all 5 samples is a low-HREE-c host. (3) peaks range from460Ma to 630 Ma. (4) εHf ranges from 10 to −28, signifying derivationmostly from recycled crust. (5) TDMc Hf of 1.3 to1.5 and 1.9 to 2.5 Gadate the derivation from older crustal material, seen best in the AmeryGroup (Fig. 13d), and includes the main peaks of TDMc , except theslightly younger 1.25 Ga of the E-WM and 1.2 Ga of the AmelangPlateau Formation (Fig. 13g, h).

Properties (1) to (4) characterize Pan-Gondwanaland crust thatwas intensely reworked during the assembly of Gondwanaland(Veevers, 2003, 2007). Property (5), TDMc Hf , indicates the minimumage for the average continental crust source of the magma fromwhichthe zircon crystallized. The range of 1.3 to 2.5 Ga overlaps the 1.6–2.4 Ga episode of formation of “juvenile continental crust II” of Condie(2001) (Fig. 15, shaded).

The minor 1200–1000 Ma cluster (c of Veevers et al., 2006),expanded to include the 1000-900 Ma peaks in AM-04 and the AmeryGroup, presumably derived from Beaver Terrane ages upslope inthe GSM–VSH complex (Veevers and Saeed, 2008), has these proper-ties: (1) major rock type hosts are mafic granitoids, dominant in 4 ofthe 5 analysed samples. (2) the minor rock type in 3 samples is a low-HREE-c host. (3) major peaks range from 919 Ma to 980 Ma; minorpeaks are at 1000 Ma, 1050 Ma, 1090 Ma (Sodruzhestvo Group), and1150 Ma. (4) εHf ranges from 15 to −28, signifying derivation fromfertile crust (depleted mantle) and recycled crust. (5) TDMc Hf of 1.5 to1.8 Ga dates the derivation from older fertile and recycled crustalmaterial.

TDMc peaks (Fig. 13, at top) fall within 1.0 to 1.6 Ga (fine brokenlines), 1.6 to 2.4 Ga (coarse broken lines), and 2.4 to 3.7 Ga (coarserbroken lines).

Fig. 11. U–Pb ages (Ma) and TDMC ages (Ga) of grainsb2500 Ma and TDM agesN2500 Ma in probability distribution diagrams of samples arranged in stratigraphical order, with bedrock

ages in the PCM–PB region (c, g) and Amery Group data (h) from Veevers and Saeed (2008). Common U–Pb ages are 500–650 Ma and 800–1100 Ma (shaded), and common TDMC ages

1.2–1.7 Ga and 1.7–2.4 Ga (line pattern), with four peaks at 2.1 Ga, and TDM ages 2.8–3.7 Ga. (d). Low-HREE-c grains are shown by bars, and in 740A and the Amery Group by probabilitydiagrams inwhite. (a) AM04, fromFig. 4. (b) 1167A, fromFig. 6. (c) bedrockwest of 70°E, symbols in (g). V,W, X, Y, Z denote peaks in the probability distribution of detrital zircons in thePrecambrian lithostratigraphic groups of the S PCM (Phillips et al., 2006). FromVeevers and Saeed (2008). (d)1166A, from Fig. 8. (e) 741A, from Fig. 9. (f) 740A (fromVeevers and Saeed,2008); the 650–500Ma cluster, with 5 low-HREE-c grains, has negative εHf signifying derivation at TDMC =2.2 Ga fromolder crustal sources; the 1100–800Ma clusterwith 19 low-HREE-c grains, was derived at TDMC =2.1 and 2.0 Ga from older crustal sources. (g) bedrock east of 70 °E (from Veevers and Saeed, 2008), with key to symbols. (h) Amery Group (from Veeversand Saeed, 2008); the 650-500 Ma cluster, with 5 low-HREE-c grains, has positive and negative εHf signifying derivation at TDMC =1.3-2.5 Ga from mixed juvenile mantle and oldercrustal sources; the 1100–800 Ma cluster has positive εHf and was derived at TDMC =1.5–1.8 Ga from juvenile mantle sources.


Fig. 12. Early Permian Gondwanaland platform showing only those ice and water flow vectors radiating from central Antarctica (modified from Veevers and Saeed, 2008). Lettersa-h locate samples in Fig.11, and numerals 1-11 locate samples in Fig.14. Themodern GSM, delineated by the 2 km elevation contour (Jamieson et al., 2005; Stewart Jamieson, pers.comm., 2006), are surmounted by Dome Argus (DA); the VSH, delineated by the 1 km elevation contour, are set in a wider upland limited by the 0.5 km elevation contour. LakeVostok (LV), with the location of the 5G-1 core-hole, has ice flow from the northwest (Leitchenkov et al., 2007). The other Quaternary ice flow is northward from an ice divideacross Dome Argus across the GSM into the Lambert Glacier (Fig.1). Detrital zircons aged d+ 700–500Ma and c 1200–1000Ma (circles) include those at Lake Vostok, (Leitchenkovet al., 2007) and Mt Rymill (Mt R)/Mt Maguire (Mt M) (Veevers et al., 2008). Also shown are paleoflow in the Cambrian (double-shafted arrow) in the central TransantarcticMountains (Myrowet al., 2002; Goodge et al., 2004), whereMiddle-Late Cambrian (≤520Ma) sandstones contain detrital zirconswith peak ages at∼1050Ma and 525Ma (Goodgeet al., 2002). Similar aged populations are found in the Cambrian sediment of the Ellsworth–Whitmore Mountains block (EWMB) andWelch Mountains (Flowerdew et al., 2006,2007) and KanmantooGroup (Veevers, 2000, p. 200), Ordovician turbidite of SE Australia (Veevers, 2000, p. 204), other Permian samples of DronningMaud Land (DML)— SE Africa(Veevers and Saeed, 2007), Permian–Triassic of the Lambert-Mahanadi rift system (Veevers and Saeed, in press; Veevers et al., 2008), the Quaternary sediment of the Amery IceShelf and PB (this work), and the Triassic Hawkesbury Sandstone (Veevers et al., 2006; Veevers and Saeed, 2007). The boxed data from detrital zircons in the Lambert and LakeVostok regions indicate the age and composition of the upslope provenance in the GSM–VSH, and with other downslope data from SE Australia and DML define a wider CentralAntarctic Provenance (CAP), with differences shown in square brackets. Letter symbols, from Veevers et al. (2006), are d+ (700–500 Ma), c (1200–1000 Ma), aa (2300–1950 Ma),aaa (2900–2600 Ma).


Fig. 13. From the top, ages of formation of crust from depletedmantle and the 2.1–1.8 Ga epoch of collisional belts (Zhao et al., 2002), TDM Hf and Ndmodel ages of samples grouped (brokenlines) over the intervals Z (3.7–2.4Ga), Y (2.4–1.6Ga), andX (1.6–1.0Ga), U–Pb ages in clusters aaaa (3350–3050Ma), aaa (2900–2600Ma), aa (2300–1950Ma), c (1200–1000Ma), expanded to900Ma to include peaks in AM04 and the Amery Group, dd (850–750Ma), and d+ (700–460Ma), loosely correlated with letter symbols of Veevers et al. (2006), TDMc and TDM Hfmodel ages,rock-type hosts, and εHf values of zircons fromsamples (except the EWMBsample, #g) downslope from the central Antarctic provenance, located on Fig.12. Shading indicates correlation of theU–Pb ages with the clusters. (a) to (h) located on Fig. 12. (a) sample K2258 of the Triassic Hawkesbury Sandstone (Veevers et al., 2006). Ages of low-HREE-c grains inwhite. (b) sample of pre-Holocene sand fromtheAM04core-hole on theAmery IceShelf (Fig. 4). The agesof 2 low-HREE-cgrains are shownabove. (c) samples fromPleistocene sand inODP1167A,PB (Fig. 6). Theagesof25 low-HREE-c grains are shown above. (d) Permian–Triassic AmeryGroup about Beaver Lake, fromVeevers and Saeed (2008). Ages of low-HREE-c zircons inwhite.(e) ages (V,W, Yof Veeversand Saeed, 2008) of detrital zircons from the downslope 970–650Ma Sodruzhestvo Group at CumpstonMassif andMtMaguire (Phillips et al., 2006). (f) ages of zircons and rocks types of hostrocks, and TDM Nd model ages of the b5 µm fraction from a Permian morainal clast of siltstone near Mt Maguire and Mt Rymill (Veevers et al., 2008); and ages of 17 detrital zircons and 5 ?metamorphicmonazites (Leitchenkov et al., 2007) andwhole-rock TDMNdmodel age of 1.88 Ga and εNd value of −15 (Delmonte et al., 2004) from inclusions of quartzose siltstone in ice fromLakeVostok core-hole5G-1. (g)probabilitydistributiondiagramsofU–PbandHfmodel ages, and εHfvaluesofdetrital zirconsofCambrian sediments, Ellsworth–WhitmoreMountains (Veeversand Saeed, 2007), originally from Flowerdew et al. (2007). (h) samples KF30 and 43 of the Permian Amelang Plateau Formation in Dronning Maud Land (Veevers and Saeed, 2007).


Table 6Detrital zircons from the Permian (KF30+43) of DML compared with those from theCambrian of the E-WM (Veevers and Saeed, 2007)

d+ 700–460 Ma U–Pb peak Ma εHfKF30+43 625, 520 +8 to −7E-WM 650–535 +10 to −10

c 1200–1000 MaKF30+43 1103 +14 to 0E-WM 1048 +14 to 0

Overall TDM GaKF30+43 1.6–1.2 peak–0.8E-WM 2.0–1.25 peak–1.0

Table 7Properties of the zircons in the individual downslope samples in Fig. 13

TDMc peak Ga 1.21.251.41.451.61.751.881.92.02.12.12.152.22.452.723.03.23.5

Cluster d+ 700–460 Mamajor rock type felsic and mafic granitoids 5/5

mafic granitoids 2/5minor rock type low-HREE-c host 5/5main peak Ma 460

512516534536570

εHf 8 to −79 −288 −328 −328 −40

TDMc derived Ga 1.351.451.51.92.12.5–1.3

Cluster c 1200–900 Mamajor rock type mafic granitoids 4/5minor rock type low-HREE-c host 3/5main peak Ma 919

93694098010601103

εHf 10 to −2811 −1211 −1214 −015 +5

TDMc derived Ga 1.251.65–1.351.71.8–1.51.8

Top TDMc Hf peak for all samples, including TDM Nd of whole rock (clay) in italics. BelowThe main properties are listed for the clusters d+ (700–460 Ma) and c (1200–1000–900 Ma).


Strikingly similar are the properties of the Cambrian E-WM andPermian DML samples (Fig.13g, h) (Table 6). Both U–Pb ages and εHf inclusters d+ and c, and the TDM model ages of all the zircons areeffectively the same. This suggests (1) that the provenance remainedunchanged from the Cambrian to the Permian, and (2) that the E-WMsample lay downslope from the central Antarctic provenance incompany with the DML sample, as shown by paleoslope indicators.

8.4. Comprehensive set of U–Pb ages of zircons in downslope samples

d+ (700–460 Ma) (Table 7) is the dominant cluster (reflecting thePan-Gondwanaland events) in all the samples except the older(than d+) Skelton Group and the lithostratigraphic groups of the SPCM (Fig. 14, #7, #10). These groups define cluster c (1200–900 Ma)(Table 7) or Grenville age provenance in the TransantarcticMountains (filled circle) (Wysoczanski and Allibone, 2004) and ascluster V in the 970–650 Ma Sodruzhestvo Group (Fig. 13e) in the SPCM. Because the Sodruzhestvo Group was deposited from north-flowing paleocurrents (Phillips et al., 2005, 2006), its 1130–970 Madetrital zircons must have come from the south, in the direction ofthe GSM, and not from rocks of this age in the Beaver, Fisher, andClemence areas, which lay downslope. This suggests that zircons ofthis age were generated in orogens to the south, at the same time asthe 1000–900 Ma collision (Mezger and Cosca, 1999; Rogers andSantosh, 2004) of India (Eastern Ghats) and adjacent Antarcticterrane (Napier–Rayner Complex) and during the 1150–1000 Mafinal stage of the “worldwide Grenville orogenic event at 1.3–1.0 Ga”taken as marking the assembly of the supercontinent called Rodinia(Condie, 2001).

Cluster a (1800–1500 Ma), poorly defined in 6 samples (Fig. 14),correlates with the Kimban orogeny of the Gawler craton of SouthAustralia and the Nimrod orogeny of the central TAM (Veevers et al.,2006). The other clusters are defined in the large sample (n=1212) ofthe lithostratigraphic groups of the S PCM (Fig. 13e; Fig. 14, #10): aa(2300–1950 Ma) by cluster W; aa' (2600–2400 Ma) by X; aaa (2900-2600Ma) by Y; and aaaa (3350–3050Ma) by Z. Because aa and aaa arefound in the Sodruzhestvo Group, their provenance is south of the SPCM. Because the ages of the other clusters (aa'— 2600–2400 Ma andaaaa— 3350–3050 Ma) are represented in the S PCM, we suggest thatthe southern provenance may be an extension of the PCM.

8.5. Summary of TDM model ages

Pulsed crustal growth at 1.2, 1.9 (1.8–2.1 Ga, Zhao et al., 2002), 2.7,and 3.3 Ga is matched by 187Re-187Os mantle depletion ages at 1.2, 1.9,and 2.7 Ga (Pearson et al., 2007) and by Hf model ages of detrital and

Fig. 14. Probability distribution diagrams of U–Pb ages of detrital zircons in samples downsloptable 1). (1) to (11) located on Fig.12. (1) K2258— 240MaHawkesbury Sandstone (Fig.13). (2) 52002). (3) CF256— 455Ma Sunlight Creek Formation from the Genoa River (Fergusson and Fathe Lachlan Fold Belt (LFB) (Fig. 16) (light line). (5) 485-460 Ma Stony Head Sandstone, NE Ta(Black et al., 2004). (7) YC 130/95 and AA 195/86— ∼750 Ma Skelton Group, southern Victori268G 505 Ma Goldie Formation, Beardmore Glacier, central Transantarctic Mountains (Golithostratigraphic groups, southern PCM (Phillips et al., 2006; Veevers and Saeed, 2008). (11)2007).

inherited zircons in SE Australia (ultimately from the East Antarcticprovenance) with δ18Ob6.5‰ of 1.9 and 3.3 Ga (Kemp et al., 2006).These ages of newly formed crust from depleted mantle (and not from

e from the central Antarctic provenance in clusters d+ to aaaa (fromVeevers et al., 2006,14U1— 455MaBumballa Formation from the Shoalhaven River (Fergusson and Fanning,nning, 2002) (heavy line), and (4) a sample (n=201) of detrital and inherited zircons fromsmania (Black et al., 2004). (6) 450–420 Ma upper Mathinna Supergroup, NE Tasmaniaa Land (Wysoczanski and Allibone, 2004). The filled circle indicates cwithout d+. (8) 98-odge et al., 2002). (9) Amery Group, northern PCM (Veevers and Saeed, 2008). (10)KF43 — 290 Ma Amelang Plateau Formation, Dronning Maud Land (Veevers and Saeed,

Fig. 15. (a) the three stages of growth of juvenile continental crust according to Condie (2001, p. 225). (b) the 4 ages of formation of crust from depleted mantle (Kemp et al., 2006;Pearson et al., 2007), with the 2.1–1.8 Ga epoch of collisional belts (Zhao et al., 2002). (c) TDM model ages from the Transantarctic Mountains (TAM) bedrock (Veevers et al., 2006).(d) to (f) TDMc and TDM Hf model ages of detrital zircons (Table 7) from the CAP as peaks (solid squares), and by derivation from the depleted mantle of 680–460 Ma (open squares)and 1340-860 Ma (triangles) clusters. (g) TDM Nd model ages from the PCM–PB bedrock (Fig. 11).


the recycling of old crust), together with Condie's (2001) three stagesof growth of juvenile continental crust are shown on Figs.13 and 15 forcomparison with our data.

Figs. 13 and 15 show that grouping Y (2.4–1.6 Ga) corresponds withCondie's (2001) Stage II, and includes the CAP peaks and depletion agesof the d+ and c clusters, and model ages of bedrock in the PCM–PB andTAM regions. Within this stage, the 2.1–1.8 Ga epoch is represented bythe major TDMc peaks of the CAP, including those of all 5 samplesdescribedabove (Fig.11a, b, d, e, f), andby theU–Pbage clusteraa (2300–1950 Ma). The older grouping Z (3.7–2.4 Ga) corresponds with Condie's(2001) Stage I, and includes the minor CAP peaks and depletion ages ofthe aaa and aaaa clusters, and model ages of bedrock abundantly in thePCM–PB region and less abundantly in the TAM region. The youngergrouping X (1.6–1.0 Ga), part of Condie's (2001) Stage III, includes 5 CAPpeaks, many depletion ages of the d+ and c clusters, and model ages ofbedrock principally in the PCM–PB region, including those of the 500–50 Ma alkaline province in the Amery area. The crust/mantle events at1.2 and 1.9 Ga are represented by CAP peaks and depletion ages; the 2.7and 3.3 Ga events are not seen.

Altogether, these correlations indicate that the CAP may be anextension of the geology of the PCM–PB, a complex of c cratonsembedded in a matrix of d+ fold belts much of which from crustderived from the depleted mantle at ∼1.9 Ga and from recycled 2.1–1.8 Ga crust.

Further information about TDMc ages of the CAP is provided byKemp et al.'s (2006) analyses of zircons from SE Australia.

8.5.1. New U–Pb and Hf-isotope data from SE AustraliaNew information about the zircons of SE Australia, in particular TDMC

ages, is provided by U–Pb, Hf-isotope, and oxygen-isotope analyses ofdetrital and inherited zircons in the Lachlan Fold Belt (Kempet al., 2006).According to these authors, zirconswithΔ18Ob6.5‰ formed frommeltsthat contained a major mafic component derived from the depletedmantle and a minor to negligible sedimentary component. The TDM

C

model age of these zircons indicates the time since the source of theparental magmas separated from the mantle, or the age of formation ofthe continental crust. Their work showed that crust generation in theregion that supplied the zircons (which from paleogeographicalevidence was East Antarctica – Veevers et al., 2006) was limited tomajor pulses at 1.9 Ga and 3.3 Ga. The pulse at 1.9 Ga fallswithin the2.4–1.7 Ga range of TDMC peaks of detrital zircons in the Amery – PB area(Fig. 11) and in the middle of the 2.2–1.4 Ga range of PCM–PB bedrock,that corresponds in turn to Condie's (2001) Stage II growth of juvenilecrust (Fig. 15). The other pulse at 3.3 Ga is represented by 3.2 Ga ages inthe TAM and PCM–PB and a CAP peak, at the outset of Stage I.

The U–Pb age data of the ∼475 Ma Lachlan Fold Belt sample matchthose of the ∼240 Ma Hawkesbury Sandstone (Fig. 16) and the

∼455 Ma Sunlight Creek Formation (Fig. 14, #3) within the clusters ofd+, c, aa, and aaa, in evidence of the unchanging U–Pb age structure ofthe CAP provenance. The εHf distribution in d+ differs slightly: in the∼240 Ma Hawkesbury Sandstone, it is concentrated about 0, with along tail to -53.5; in the Lachlan Fold Belt, it is concentrated about −7,with a tail to −30. And the TDMc ages in the Hawkesbury Sandstone(1.0− (1.4, 1.75)−2.1 Ga) are younger than those in the Lachlan FoldBelt (1.3− (1.6, 2.0)−2.6 Ga). The differences may be attributed todifferent εHf and TDMc in those parts of the CAP provenance sourcedin the Ordovician and Triassic.

8.6. Summary of the GSM–VSH provenance

From their reflection in the proximally downslope samples, theproperties of the GSM–VSH provenance during times within theNeoproterozoic and Phanerozoic Eons are as follows.

Major components are (1) d+ (700–460 Ma): mafic granitoids andlow-HREE-c hosts; εHf ranges from 9 to −28, signifying derivationfrom fertile and recycled crust; TDMc Hf of 2.5 to 1.3 Ga, and (2) c(1200–900 Ma): mafic granitoids and low-HREE-c hosts; εHf rangesfrom 11 to −28, signifying derivation from fertile and recycled crust;TDMc Hf of 1.8 to 1.3 Ga.

Minor components are (3) aa (2300–1950 Ma): granitoids andmafic rocks; εHf ranges from 0 to −20, signifying derivation mostlyfrom recycled crust; TDM Hf of 2.7 to 2.5 Ga. (d) aaa (2900–2600):granitoids; εHf ranges from 1 to −8, signifying derivation mostly fromrecycled crust; TDM Hf of 3.2 Ga.

Because the Eocene 1166A sample is indistinguishable from thoseof AM04 and 1167A, we infer that 1166Awas also downslope from theGSM in the Eocene.

The Early Cretaceous 741A is exceptional in its restriction of zirconU–Pb ages to 580-520 Ma. We interpret this exception as due to thedisturbed (?reversed) drainage from the interior about the time ofcontinental breakup so that local ∼550 Ma mafic granitoids andalkaline (low-HREE-c hosts) rocks, as in the Larsemann Hills and atLanding Bluff (Fig. 2) became the exclusive provenance of thesediment. This is consistent with Arne's (1994) and Lisker et al.'s(2003, p. 13) view that “The Cretaceous denudation/rifting stage in theNPCM [northern PCM] was probably related to tectonic reactivation ofthe earlier Permo-Triassic rift during the initial separation of Indiaduring the breakup of Gondwana”.

8.7. Central Antarctic Provenance (CAP)

The GSM–VSH provenance is expanded to a wider CentralAntarctic Provenance (CAP) by the addition of the distal samples ofthe Hawkesbury Sandstone (HS) (Fig. 14, #1) and the Amelang Plateau

Fig. 16. U–Pb ages, TDMc and TDM Hf model ages, and εHf values of zircons from SE Australian samples. (a) sample K2258 from the Triassic Hawkesbury Sandstone, from Veevers andSaeed (2007), additionally with rock types. (b) Lachlan Fold Belt detrital (Ordovician [∼475 Ma] Adaminaby Beds) and inherited (∼430 Ma granodiorites and dacite) zircons, all fromKemp et al. (2006). Above, U–Pb ages (SHRIMP) of 201 zircons in a probability distribution diagram and histogram with 20 million-year wide bins, and probability distributiondiagram of TDMC ages (calculated with a value of 176Lu/177Hf=0.015) of 67 grainsb2500 Ma. Below, εHf versus U–Pb ages of 60 zircons.


Sandstone (APF) (14, #11). All 6 clusters are seen in the HS, but onlythe youngest 3 in the APF. Both differ from other samples in the εHf ofthe c cluster: HS εHf=15 to 5, APF εHf=14 to 0, both wholly positive,compared with εHf=11 to −28 of the other samples. The c cluster ofthe Cambrian metasediment in the distal EWMB also has positiveεHf=14 to 0. The difference in εHf of the c cluster suggests that theGSM–VSH provenance with mainly negative εHf is bounded on either

side by the wider CAP with positive εHf. The samples of the distal HS,APF, and EWMB have peaks of TDMc=1.35, 1.2 , 1.25 Ga, significantlylower than those of the proximal samples: TDMc=2.1, 1.9, 1.45 Ga.

Table 5 lists the properties of the samples downslope from (andhence that potentially reflect) the central Antarctic provenance. Thepeak TDMc Hf ranges from 1.2 to 3.5 Ga, and TDM Nd of whole-rocksamples of clay are 1.88 and 2.72 Ga.


Goodge et al. (2004) inferred that Cambrian samples in the centralTransantarctic Mountains had a provenance of Grenville and Pan-African ages in DML and the East African orogen, flanking the Kalaharicraton. Maidment et al. (2007) found detrital zircons from Cambrianand Ordovician sedimentary rocks in central Australia with ages of1.2–1.0 Ga (c) and 0.7–0.5 Ga (d+), and inferred that “the ultimatesource of this sediment might have been east Antarctica or theMozambique Orogenic Belt of east Africa”. We regard centralAntarctica as the more likely provenance because in the Cambrian itwas the higher part of the Transgondwanan Supermountain whereasthe Mozambique Belt was only an eroded remnant (Squire et al.,2006).

The Pleistocene 1167A (Fig. 13c) and Permian APF (Fig. 13, h) lackzircons older than 1350 Ma, presumably because older parts of theprovenance were not accessible in these areas.

In summary, other than this difference, the U–Pb age distributionsthrough the ages of deposition, from the Neoproterozoic SodruzhestvoGroup, through the Ordovician sediment of SE Australia, Permian APFand Mt Rymill siltstone, Permian–Triassic Amery Group, Triassic HS,

Fig. 17. Hypothetical super-terrane of sub-glacial Antarctica. Cratons of age c (and minor agbounded (dot-and-dash line) by the East African–Antarctic Orogen and the Prydz–LeeuwinPaleoflow and age (Ma) indicated by arrows. Extended from Veevers et al. (2006, fig.. 37) froCambrian to Devonian quartzose sandstones with detrital zircons in d+ and c clusters in VictoRange (MR) on the Pacific margin, the Grunehogna (G) craton of Dronning Maud Land, the Npossibly extends (dot-and-dash line) as exposed c and d+ terranes into Dronning Maud LandFraser regions. The ages of sediment shed from the GSM are given in Ma. TDM (Ga) are shownand its inferred specifications are given in the box. Thewider central Antarctic provenance (CAside by positive εHf. APF = Amelang Plateau Formation; EWMB = Ellsworth–Whitmore MouMiller Range; MtW = Mt Welch; VSH = Vostok Subglacial Highlands; WI = Windmill Islands

and Quaternary 1167A, AM-04, and Lake Vostok siltstone, are thesame, and suggest an unchanging provenance at these times duringthe past 1000 Ma, confirming Dalziel's (1992) view of the longevity ofthe GSM.

9. Discussion and conclusions

In the broadest terms, the GSM–VSH (Fig. 17), as reflected in thedownslope samples, comprise rocks dominantly of d+mafic granitoidsand low-HREE-c hosts, εHf of 9 to -28, derived from fertile andrecycled crust at model ages (TDMc) of 2.5–1.3 Ga. Low-HREE zirconsreflect host alkaline rocks, interpreted (Veevers, 2007) as generatedduring the assembly of Gondwanaland from oblique stresses 1 and 2.Less dominant contributions are from c mafic granitoids and low-HREE-c hosts, εHf of 11 to −28, derived from fertile and recycled crustat model ages (TDMc) of 1.8–1.3 Ga.

Contributors of minor amounts of zircons are aa granitoids andmafic rocks, εHf 0 to −20, derived from recycled crust at model ages(TDM) of 2.7–2.5 Ga, aaa granitoids, εHf 1 to −8, derived from recycled

es aa, aaa, and aaaa), embedded in a matrix of Pan-Gondwanaland fold belts of age d+Belt on two sides, the Ross Orogen on the Pacific side, and Australia on the fourth side.m data above (Fig. 12), Veevers and Saeed (2007, 2008), and Veevers et al. (2008), withria (Squire et al., 2006). Small exposures of aaa (Archean) rocks are known in the Millerapier Mountains, the southern PCM, and the Windmill Islands (WI). The super-terrane, into the PCM–PB, Rayner, and Eastern Ghats regions, and into the Wilkes and Albany-for rocks of the Ross Orogen. The dotted line circumscribes the upland of the GSM–VSH,P) is divided into a central sectorwith negative εHf in its c aged rocks bounded on eitherntains Block; G = Grunehogna craton; GSM = Gamburtsev Subglacial Mountains; MR =.


crust at a model age (TDM) of 3.2 Ga, and aaaamafic granitoids, εHf 0to −20, from recycled crust at model ages (TDM) of 3.6–3.5 Ga.

Following Veevers et al. (2006, fig. 37), we sketch the solidgeology of Antarctica (Fig. 17) as a mosaic of cratons of ages mainly cand minor aa, aaa, and aaaa, embedded in a matrix of Pan-Gondwanaland fold belts of age d+. The shape of the modelledsuper-terrane is inspired by the composite cogs of the West African,Congo, Amazonia, India-East Antarctica-West Australia that rotatedwithin amatrix of Pan-Gondwanaland fold belts (Veevers, 2003). Thesize of the individual cratons resembles that of the Gawler Block, andin age that of the nearby 1300–1000 Ma Musgrave Block of centralAustralia.

The 550–490 Ma subduction-related Ross orogen borders thesuper-terrane, and, as suggested by its model ages (2.0–0.9 Ga) thatoverlap the 1300–900Ma range of exposed rocks, may be underlain bythe super-terrane.

The Pinjarra orogen, including the Leeuwin Complex (Collins,2003), contains d+ ages as well as c. Fitzsimons (2003) shows threepotential pathways for the Pinjarra orogen across East Antarctica,in agreement with our inferred super-terrane of c cratons embeddedin d+ fold belts.

Cratons of age c alone are indicated by Neoproterozoic (970–650 Ma) samples in the PCM and southern Victoria Land, and byPermian (275, 255Ma) ones in the Collie Basin. Both c and d+ terranesare indicated by samples that were deposited (in decreasing age) at525 Ma in South Australia, 500 Ma along the Pacific margin ofAntarctica, 450 Ma in SE Australia, 300–200 Ma in the Mt Rymill–Amery–Godavari rift system, 290 Ma in DML, 275–255 Ma in thePerth region, and 240 Ma in the Hawkesbury Sandstone of SEAustralia. In turn, the Hawkesbury Sandstone contributed c and d+aged zircons to the shelf sand of eastern Australia (Sircombe, 1999;Veevers et al., 2006). Zircons of d+ and c ages in Pleistocene sandoffshore PB and in modern sand beneath the Amery Ice Shelf (thispaper) comemainly from the GSM, withminor recycling of Permian–Triassic sediments.

The wider central Antarctic provenance (CAP) is tentativelydivisible into a central sector with negative εHf in c aged rocksbounded on either side by those with positive εHf. The CAP or parts ofit provided sediment at various times in the Neoproterozoic,Cambrian, Ordovician, Permian, Triassic, and Quaternary.

Correlations of U–Pb ages and TDM model ages indicate that theCAP, a complex of c cratons embedded in a matrix of d+ fold belts, maybe an extension of the geology of the PCM–PB. Much of the crust wasderived from the depleted mantle ∼1.9 Ga and from recycled 2.1–1.8 Ga crust.

The profusion of detrital zircons in the Lambert Graben with agesof 1.3–1.0 Ga (Grenville) and 0.7 to 0.5 Ga (Pan-Gondwanaland) andnegative εHf indicates intense reworking of the juvenile crust duringthese epochs of supercontinental assembly.

The intermittent uplift of the GSM–VSH over the past 1000 Mapoints to alternations of weak (thin) and strong (thick) crust. Theuplift of the GSM in the Permian and later is attributed to crustalshortening by farfield stress during the 320 Ma mid-Carboniferouscollision of Gondwanaland and Laurussia (Veevers, 1994). Müller et al.(2007) show crustal thickness N46 km extending from 100°E toDronning Maud Land in East Antarctica, co-extensive with the GSM–

VSH between 60°E and 100°E.Earlier uplifts in (1) the ∼500 Ma Cambrian may have followed the

650–500 Ma assembly of Gondwanaland, and in (2) the 950-650 MaNeoproterozoic may have followed the 1000-900 Ma collisionalevents in the Eastern Ghats–Rayner Province at the end of the 1300-1000 Ma assembly of Rodinia (Rogers and Santosh, 2004).

The extensional event attending the Cretaceous breakup ofAntarctica and India may have disrupted the pattern of drainage tocause the (exceptional) lack of zircons older than 580 Ma in the EarlyCretaceous sediment of 741A.

Acknowledgements

We thank theOceanDrilling Program (ODP) for the offshore samplesand the Amery Ice Shelf–OceanResearch program for sample AM04.Wethank Chris Fergusson for Excel files of Ordovician samples of SEAustralia, Mike Flowerdew for files of Early Paleozoic samples from theEllsworth–Whitmore Mountains, and Glen Phillips for files of samplesfrom the lithostratigraphic groups of the S PCM. We thank StewartJamieson for providing an updated copy of Fig. 1 of Jamieson et al.(2005), German Leitchenkov for a pre-print, and Alexander Golynsky foradvice and help with references. Supported by ARC DP0344841 andgrants from Geoscience Australia and Macquarie University. This studyused instrumentation funded by ARC LIEF and DEST SystemicInfrastructure Grants, Macquarie University, and industry. Contribution501 from the ARC National Key Centre for Geochemical Evolution andMetallogeny of Continents www.es.mq.edu.au/GEMOC). O'Brien pub-lishes with the permission of the Chief Executive Officer, GeoscienceAustralia. Finally, we would like to thank two anonymous reviewers fortheir helpful comments and suggestions.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, inthe online version, at doi:10.1016/j.sedgeo.2008.08.003.

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Provenance of the Gamburtsev Subglacial Mountains from U–Pb and Hf analysis of detrital zircons in...

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