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Composition and age of the East Antarctic Shield in eastern Wilkes Land determined by proxy from Oligocene-Pleistocene glaciomarine sediment and Beacon Supergroup sandstones, Antarctica

John W. Goodge and C. Mark Fanning
Composition and age of the East Antarctic Shield in eastern Wilkes Land determined by proxy from Oligocene-Pleistocene glaciomarine sediment and Beacon Supergroup sandstones, Antarctica
Geological Society of America Bulletin (July 2010) 122 (7-8): 1135-1159

Abstract

The Precambrian East Antarctic Shield played a central role in the tectonic evolution of Rodinia and Gondwana, as well as growth of the East Antarctic Ice Sheet, yet little is known about its ice-covered interior. Glaciogenic deposits of Oligocene-Miocene and Pleistocene age on the Wilkes Land margin include glaciomarine diamictons containing basement rock clasts and fine-grained siliciclastic detritus, which provide proxy samples of the continental basement. Rock clasts obtained by dredge (81% metamorphic, 14% igneous, and 5% sedimentary lithologies) provide petrographic, geochemical, and age information about the glacial source area. Igneous clasts with Ross orogen U-Pb zircon ages (ca. 500 Ma) include a notably old ca. 585 Ma granitoid; they and Ross-age metamorphic rocks give discrete inherited-zircon age populations of 670-780, 900-1300, 1740-2300, and >2700 Ma that reflect basement sources. Paleoproterozoic rock clasts (granitoid, charnockite gneiss, and granulite gneiss) range from ca. 1720 to 1740 Ma. Detrital zircon populations from glaciomarine sediments vary with depositional age but show common terrigenous provenance ages of 460-660, 1045-1315, 1545-1815, and 2420-2605 Ma, which overlap those from inherited zircons in the Ross granitoids. Detrital zircon ages from onshore Permian and Triassic terrestrial sedimentary rocks reveal a different provenance and indicate that the glaciogenic deposits do not contain significant second-cycle material from older interior basins. Together, these data suggest that metamorphic rock units with distinctive Neoproterozoic, Paleoproterozoic, and Archean ages dominate East Antarctic Shield basement inland from the eastern Wilkes Land margin, and that Ross-age granitoids either intruded or were derived by partial melting of this composite metamorphic basement.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 122
Serial Issue: 7-8
Title: Composition and age of the East Antarctic Shield in eastern Wilkes Land determined by proxy from Oligocene-Pleistocene glaciomarine sediment and Beacon Supergroup sandstones, Antarctica
Affiliation: University of Minnesota, Department of Geological Sciences, Duluth, MN, United States
Pages: 1135-1159
Published: 201007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 72
Accession Number: 2010-050191
Categories: StratigraphyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010133
Illustration Description: illus. incl. charts, 3 tables, geol. sketch maps
S78°00'00" - S34°00'00", E104°00'00" - E179°00'00"
Secondary Affiliation: Australian National University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201027
Program Name: DSDPDeep Sea Drilling Project
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