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The Permo-Triassic Gondwana Sequence, Central Transantarctic Mountains, Antarctica: Zircon Geochronology, Provenance, and GEOSPHERE; V

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The Permo-Triassic Gondwana Sequence, Central Transantarctic Mountains, Antarctica: Zircon Geochronology, Provenance, and GEOSPHERE; V Research Paper GEOSPHERE The Permo-Triassic Gondwana sequence, central Transantarctic Mountains, Antarctica: Zircon geochronology, provenance, and GEOSPHERE; v. 13, no. 1 basin evolution doi:10.1130/GES01345.1 David H. Elliot1, C. Mark Fanning2, John L. Isbell3, and Samuel R.W. Hulett4 20 figures; 1 table; 3 supplemental files 1School of Earth Sciences and Byrd Polar and Climate Research Center, Ohio State University, Columbus, Ohio 43210, USA 2Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia 3Department of Geosciences, University of Wisconsin–Milwaukee, Wisconsin 53201, USA CORRESPONDENCE: elliot.1@ osu .edu 4Department of Earth, Atmospheric and Planetary Sciences, Notre Dame University, Notre Dame, Indiana 46556, USA CITATION: Elliot, D.H., Fanning, C.M., Isbell, J.L., and Hulett, S.R.W., 2017, The Permo-Triassic Gond- wana sequence, central Transantarctic Mountains, ABSTRACT (McLoughlin and Drinnan, 1997a, 1997b) are part of the East Gondwana interior Antarctica: Zircon geochronology, provenance, and rift system (Harrowfield et al., 2005) and are linked byGlossopteris and palyno- basin evolution: Geosphere, v. 13, no. 1, p. 155– The most complete Permian–Triassic Gondwana succession in Antarctica morphs to the Trans ant arc tic Mountains and other Gondwana successions. 178, doi:10.1130/GES01345.1. crops out in the central Trans ant arc tic Mountains. The lower Permian strata Vertebrate remains and plant assemblages (Glossopteris and Dicroidium were deposited in an intracratonic basin that evolved into a foreland basin in floras) provide paleontological ages for the Beacon strata, giving a Devonian Received 15 April 2016 Revision received 24 August 2016 late Permian time. Sedimentary petrology and paleocurrent data have been age for the Taylor Group and a Permian through Triassic age for the Victoria Accepted 24 October 2016 interpreted as indicating a granitic (craton) provenance and a West Antarctic Group (Truswell, 1991; Young, 1991). Pollen and spore analysis has established Final version published online 20 January 2017 volcanic provenance. To address the West Antarctic provenance and evolution a palynostratigraphy for the Victoria Group (Schopf and Askin, 1980; Kyle and of the detrital input, detrital-zircon grains from nine sandstones (plus three Schopf, 1982; Farabee et al., 1990) and enabled correlation with the Austral- sandstones reported previously) representing the full extent of the Permo-Tri- asian palynostratigraphic zonation (Mantle et al., 2010). Strata in eastern Ells- assic succession exposed on that flank of the basin, have been analyzed by worth Land and the Ellsworth Mountains have yielded Glossopteris and thus sensitive high-resolution ion microprobe. Results define three provenances: have Permian ages (Gee, 1989; Taylor and Taylor, 1992). Vertebrate faunas have an early (early to middle Permian) provenance that is dominated by zircons been recovered from Lower and Middle Triassic strata (Smith et al., 2011; Sidor having Ross orogen ages (600–480 Ma); a middle (late Permian) provenance et al., 2014). dominated by Permian zircons with subordinate older magmatic arc grains Sandstone petrology and paleocurrent data for the Victoria Group in plus lesser Ross orogen–age grains; and a late (Triassic) provenance, which is the central Trans antarc tic Mountains (CTM) established a granitic source quite variable and in which the predominant Triassic arc component ranges interpreted to be the East Antarctic craton and a volcanic source located in from very minor to significant and again with a component of Ross orogen– West Antarctica (Barrett et al., 1986). Outcrops that might be representative age grains. Detrital zircons imply a more extensive Permo-Triassic arc, in time of the potential sources in East Antarctic are confined in CTM to the Miller and space, on the Gondwana margin than is evident from outcrop data. The Range (Fig. 3). The volcanic source has been correlated with the few isolated zircon data are integrated into a model for basin evolution and infilling, pro- Permian and Triassic granitoids and gneisses along the West Antarctic margin viding broad constraints on the timing of tectonic events and the provenance. (Pankhurst et al., 1993; Collinson et al., 1994; Pankhurst et al., 1998; Mukasa and Dalziel, 2000; Elliot and Fanning, 2008). A volcanic provenance in Permian time was also recorded from Mount Weaver in the Scott Glacier region (Min- INTRODUCTION shew, 1967), and although such a source was not noted by Long (1965) for the Permian sandstones in the Ohio Range, petrological reexamination of the The Permo-Triassic Gondwana stratigraphy is best developed in the Trans- sandstones has revealed a volcanic component in the upper part of the section. antarc tic Mountains (Figs. 1 and 2), where it is divided into a lower Taylor No unequivocal tuffs have been identified in the upper part of the Permian Group (Devonian) and an upper Victoria Group (Permian to Triassic), the two Buckley Formation in the CTM despite the presence of much volcaniclastic together often referred to as the Beacon Supergroup (Barrett, 1991). In West material derived from an active magmatic arc (Collinson et al., 1994). Glass Antarctica, Permian strata crop out in the Ellsworth Mountains (Collinson et al., shards have been identified in a number of Permian and Triassic sandstones For permission to copy, contact Copyright 1992) and in small isolated outcrops in eastern Ellsworth Land (Laudon, 1987). (Collinson et al., 1994), but attempts to date the rocks have been unsuccessful. Permissions, GSA, or [email protected]. Permian and Lower Triassic strata in the northern Prince Charles Mountains Tuff beds in the lower part of the middle informal member of the siliciclastic © 2016 Geological Society of America GEOSPHERE | Volume 13 | Number 1 Elliot et al. | The Permo-Triassic Gondwana sequence Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/13/1/155/1000843/155.pdf 155 by guest on 28 September 2021 Research Paper CTM Central Transantarctic Mtns. 0° Central South MR Miller Range Prince Age Ohio Range Transantarctic Charles Victoria Land NVL North Victoria Land Mountains SVL South Victoria Land Mtns. ANTARCTICA Theron 90°E Weddell Sea Mtns. 90°W Falla 80°S 160–282m VVVV VVVV 180° VVV Lashly VVV VVVV 520+m Filchner- Triassic VVVV VVV Ronne 0° VVV Fremouw VVVV Ice Shelf VVVV 700m VVV VVVV East VVV Feather Haag N. Pensacola Mtns. Erehwon N. 250m T Antarctica VVV r a VVVV VVVV 90°W Ellsworth n 90°E Mount VVV 70°S Mtns 80°S s ctoria Group Ohio Ra. a Glossopteris Vi VVVV Buckley n t 690+m VVV 750m West CT a r Thurston I. Mt. Weaver M c Weller t i Antarctica c Permian 250m Scott Gl. MR M Fairchild Marie Shackleton Gl. 130–220m Byrd o Discovery Beardmore Gl. Fig. 3 u Mackellar Land n Ridge 60–140m Ross t 165m Byrd Gl. a SVL Ice 80°S i n Buckeye Pagoda Metschel Shelf s Triassic gneisses 275m 0–175m 0–70m Late Triassic granitoids P erm Carboniferous Permian-Triassic strata o-T rias Permian gneisses N s . ic Ross V Permian granitoids ar L Aztec c Beacon Hts Generalized areas of Sea bedrock outcrop Devonian Horlick Alexandra Arena Edge of shelf ice 0–150m 0–300m Altar 500 km New Mtn 2000 m bathymetric contour 180° Taylor Gp 70°S 300–1500m Figure 1. Location map for Antarctica. Stretched continental crust underlies the Ross Sea, Ross Sandstone (volcaniclastic: Coal Ice Shelf, and interior West Antarctica through to Ellsworth Land (the Ross embayment) and VVVV was generated during Late Cretaceous to Late Cenozoic time. Stretched continental crust also arc derived) Carbonaceous shale underlies the Filchner-Ronne Ice Shelf region and the adjacent Weddell Sea (the Weddell em- Sandstone (quartzose) bayment) but was extended during the Early–Middle Jurassic breakup of Gondwana. I.—Island; Shale, siltstone N.—Nunatak; Gl.—Glacier. Diamictite Hiatus Permian Polarstar Formation of the Ellsworth Mountains (Fig. 1) have yielded Figure 2. Simplified geologic columns for Devonian to Lower Jurassic strata in the zircons with Late Permian U-Pb sensitive high-resolution ion microprobe Trans ant arc tic Mountains (Ohio Range, central Transant arc tic Mountains, south (SHRIMP) ages of 258.0 ± 2.1 Ma and 262.5 ± 2.2 Ma (Elliot et al., 2016a). Victoria Land). Sources: Ohio Range—Long (1964, 1965); central Transant arc tic The aim of this paper is to evaluate the evolution of the Permo-Triassic ba- Mountains and south Victoria Land—Elliot (2013). Note that the marine Horlick Formation, although a siliciclastic succession of similar Early Devonian age, is not sin in the light of new and existing detrital-zircon geochronologic data. Specifi- part of the Taylor Group. Gp.—Group. cally, this paper records new detrital-zircon data for nine sandstones and inter- prets the results in terms of the evolution of the basin and the source regions. An initial program of detrital-zircon geochronology (Elliot and Fanning, 2008) REGIONAL GEOLOGY showed that the Permian upper Buckley Formation in the Shackleton Glacier region includes near contemporaneous igneous zircon grains. The possibil- The pre-Devonian basement in the CTM (Fig. 3) comprises Neoproterozoic ity existed, therefore, that reanalysis of the young zircons in these and other and Cambrian siliciclastic and volcaniclastic strata and limestones (Stump, samples using SHRIMP II in the higher resolution geochronology mode would 1995) intruded by granitoids emplaced during the Cambrian to Early Ordovi- provide refined and improved age data for those formations. cian Ross orogeny (Goodge et al., 2012). A regional erosion surface, the Kukri GEOSPHERE | Volume 13 | Number 1 Elliot et al. | The Permo-Triassic Gondwana sequence Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/13/1/155/1000843/155.pdf 156 by guest on 28 September 2021 Research Paper Mt. Weeks 175°E Surficial deposits 83°30′S Clarkson Pk. v v L. Jurassic basaltic rocks (11-4) v v Mt. Miller 83°30′S L.
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