Provenance and age constraints of Paleozoic siliciclastic rocks from the Ellsworth Mountains in West Antarctica, as determined by detrital zircon geochronology

Abstract

New sensitive high-resolution ion microprobe (SHRIMP) U-Pb detrital zircon ages from Cambrian to Permian-Carboniferous siliciclastic units in the Ellsworth Mountains constrain their provenance and maximum depositional age, as well as providing key information as to the tectonic evolution of a problematic region. The Cambrian Heritage Group was deposited in an active continental rift setting and has main zircon components of late Mesoproterozoic-early Neoproterozoic age (ca. 1300-900 Ma) with little to no contributions from older cratons. Two metavolcaniclastic samples of the Union Glacier Formation (lower Heritage Group) have U-Pb zircon ages of ca. 675 Ma, indicating proximal Cryogenian volcanism and thereby raising questions as to the depositional age of this unit. Igneous and metamorphic zircons of late Neoproterozoic-early Cambrian age (650-530 Ma) are a secondary component present in the upper part of this group. The passive-margin sediments of the overlying Upper Cambrian-Devonian Crashsite Group record an up-sequence increase in late Neoproterozoic-Cambrian detrital zircons (ca. 650-480 Ma). The youngest detrital zircons were dated at ca. 480 Ma with major peaks at ca. 530 Ma and 500 Ma. Similar patterns are recorded in the Permian-Carboniferous Whiteout Conglomerate, with main components at ca. 650-500 Ma,

Palaeozoic – Early Mesozoic geological history of the Antarctic Peninsula and correlations with Patagonia: Kinematic reconstructions of the proto-Pacific margin of Gondwana

“…This is consistent with Gondwana breakup reconstructions (Jordan et al, 2017), stratigraphic and paleomagnetic data (e.g. Dalziel and Grunow, 1992;Randall and Mac Niocaill, 2004), and the interpretation of Riley et al (2020b) that indicates Haag Nunataks was located close to the Natal Embayment or the Shackleton Range (Castillo et al, 2017), prior to translation in the Early Jurassic (Fig. 3).…”

“…The Heritage Group is at least 7.5 km in thickness and consists of volcaniclastic and shallow marine/fluvial sedimentary rocks that were deformed during the Palaeozoic Gondwanide Orogeny (Curtis, 1997). Flowerdew et al (2007), Craddock et al (2016) and Castillo et al (2017), examined the detrital zircon history of the Cambrian -Permian sedimentary successions of the Ellsworth Mountains and determined that the deposition of the Heritage Group at ~520 Ma developed in a continental rift setting at the margin of Laurentia and East Antarctica, with a primary sediment supply from Laurentia and Coats Land in East Antarctica.…”

Tracking voluminous Permian volcanism of the Choiyoi Province into central Antarctica

“…The Polarstar Formation is the youngest formation of the Paleozoic strata in the Ellsworth Mountains (Figs. 2 and 3; Elliot et al, 2016;Castillo et al, 2017a;Craddock et al, 2017). A minimum thickness of 1.2 km for the intensely folded strata of the Polarstar Formation has been estimated by combining several measured sections.…”

Stratigraphic and provenance analysis of Triassic rock units between 28-29° S, northern Chile: implications on the tectonic and paleogeographic evolution of the southwestern margin of Gondwana

“…The ECMC is exposed as small isolated xenoliths of phyllites and mica schists within Pennsylvanian plutons in the southernmost part of the study area ( Fig. 2) whose maximal depositional age is Ordovician (Ortiz and Merino, 2015; Charrier et al (2007) and Franzese and Spalletti (2001), Gondwana reconstruction modified from Torsvik and Cocks (2013) and Castillo et al (2017) and references therein. .…”