Ediacaran to lower Cambrian basement in eastern George V Land (Antarctica): Evidence from U Pb dating of gneiss xenoliths and implications for the South Australia- East Antarctica connection

Abstract

This study presents the first geochronological results on basement rocks from the Penguin-Bage-Webb (PBW) domain located east of the Neoarchean-Paleoproterozoic Terre Adélie craton, Antarctica. Investigated samples are paragneiss xenoliths hosted within early Paleozoic granitoids, which were emplaced during the Ross orogeny. Zircon UPb dating yielded ages ranging from the Archean to the Cambrian, with a dominant Ediacaran (550-635 Ma) population and maximum depositional ages around 570-575 Ma. U-Th-Pb analyses of monazite suggest that the metamorphic event that formed the gneiss samples occured at ca. 515 Ma, shortly prior to incorporation within the granitic magmas. The studied samples likely represent relics of the pre-Gondawana Pacific margin, which was subsequently deformed and metamorphosed during the early Paleozoic Ross orogeny. The obtained zircon UPb date distributions present similarities with those of the Kanmantoo and Nargoon sediments in Southern Australia and provide new constrains for the correlations between East Antarctica and South Australia before the opening of the Southern Ocean. Highlights ► Zircon and monazite U Pb ages of the gneiss xenoliths from eastern George V Land ► Inherited ages ranging from Archean to Cambrian with main Ediacaran population ► Relics of a pre-Gondwana pacific margin metamorphesed during the Ross orogeny Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Scratching the Surface: A Marine Sediment Provenance Record From the Continental Slope of Central Wilkes Land, East Antarctica

“…We propose westward transport of a minor component of detritus from the Eastern Sector via icebergs driven by the Antarctic Coastal Current to the KC14 core site. This hypothesis would account for the rare, but distinct c. 750‐500 Ma detrital age population characteristic of the basement rock and intruded granites of George V Land (e.g., Lamarque et al., 2018). Provenance from the east could also account for minor older c. 2,200‐1,700 Ma detrital zircon ages that correlate with Archean and Paleoproterozoic rocks of the Adélie Land coast (e.g., Ménot et al., 2007; Figure 8).…”

Petrochronology of the Terre Adélie Craton (East Antarctica) evidences a long-lasting Proterozoic (1.7–1.5 Ga) tectono-metamorphic evolution — Insights for the connections with the Gawler Craton and Laurentia

“…24), between the Neoarchean domain of Terre Adélie Craton and the ca. 560 Ma region east of 146°E (Lamarque et al, 2018). Similarly, a domain with ca.…”

Antarctic erosion history reconstructed by Terre Adélie moraine geochronology

“…1), bedrock exposures occur mainly along the coast, on small islands of < 1 km 2 . The Terre Adélie crystalline basement is made of high-grade metamorphic rocks (granulites) dating from the Neoarchaean ( c. 2.5 Ga) and the Palaeoproterozoic (1.6–1.7 Ga; Duclaux et al 2008, Naumenko-Dèzes et al 2020), accreted to a Neoproterozoic to lower Cambrian block in the eastern George V Land region (Lamarque et al 2018). Almost no post-Proterozoic deformation has been recognized except for discrete east to west faults and joints ascribed to rifting of the Antarctic Ocean during the Mesozoic (160–95 Ma).…”