Detrital zircon provenance of upper Cambrian-Permian strata and tectonic evolution of the Ellsworth Mountains, West Antarctica

Abstract

Detrital zircons from the upper Cambrian-Devonian sandstones (Crashsite Group; n=485) and Carboniferous tillite (Whiteout Conglomerate; n=81) of the Ellsworth Mountains, Antarctica record a steady supply of Neoproterozoic ("Pan-African") orogeny (~550-600 Ma), Grenville (~1000 Ma) and Neoarchean (~3000-3500 Ma) zircons into the northern marginal basin of Gondwana. The overlying Permian Glossopteris-bearing Polarstar Formation shales (n=85) have the same zircon provenance as underlying units but also include a dominance of depositional-age (263 Ma) euhedral zircons which are interpreted to be of local, volcanic arc origin. Modeling of detrital zircon provenance suggests that source areas were present in Pan-African and Laurentian crust throughout the Paleozoic. We also report calcite twinning strain results (12 strain analyses; n=398 twins) for the Cambrian Minaret Fm. in the Heritage range which is predominantly a layer-parallel shortening strain in the direction (WSW-ENE) of Permian Gondwanide orogen thrust transport. There is a secondary, sub-vertical twinning strain overprint. The initiation of localized lower-middle Cambrian

Tracking voluminous Permian volcanism of the Choiyoi Province into central Antarctica

“…6), consistent with previous detrital zircon data published for the Polarstar and Mt. Glossopteris formations (Elliot et al, 2016(Elliot et al, , 2017Craddock et al, 2017). The age range for zircon from these formations is contemporaneous with volcanic units of the Choiyoi Province (ca.…”

“…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.…”

“…Based on geochronology and facies comparisons, the Polarstar Formation has been interpreted as an extension of the Permo-Triassic Transantarctic Basin and separate from the Karoo Basin of South Africa and Permian deposits in the Falkland Islands (Elliot et al, 2016). Volcanogenic Permian detrital zircon for volcanoclastic sandstones of the Polarstar Formation generally range in age from 270 to 260 Ma and three zircon U-Pb ages have been determined for tuff beds: 258 ± 2 Ma, 263 ± 2 Ma, and 263 ± 1 Ma (Elliot et al, 2016;Craddock et al, 2017).…”

Long‐Term Geochemical and Geodynamic Segmentation of the Paleo‐Pacific Margin of Gondwana: Insight From the Antarctic and Adjacent Sectors

“…Detrital and igneous dates for the southern section of the South American arc compiled by Pepper et al () provide a comprehensive record of near continuous activity with several pulses of increased magma production throughout the Paleozoic and Mesozoic. The record is more scattered in the ice‐covered regions of West Antarctica (i.e., Marie Byrd Land, Thurston Island, the Ellsworth‐Whitmore block, and the Antarctic Peninsula), but limited geochronologic data available suggest that the bedrock contains Devonian through Early Jurassic magmatic and volcanic rocks (Craddock, Fitzgerald, et al, ; Craddock, Schmitz, et al, ; Millar et al, ; Mukasa & Dalziel, ; Pankhurst et al, ; Riley et al, ; Yakymchuk et al, ).…”

Provenance of the great Cambrian sandstone succession of northern Gondwana unravelled by strontium, neodymium and lead isotopes of feldspars and clays

“…Uranium–lead crystallization ages and, more recently, Hf isotopic composition of zircon grains are commonly used to identify sources of siliciclastic sediments (Thomas et al ., ; Meinhold et al ., ; Konstantinou et al ., ; Craddock et al ., ; Malone et al ., ). However, it is important to recall that the sediments of the Cambro–Ordovician sandstone succession contain other minerals that carry important complementary provenance information.…”