Zircons and clay from morainal Permian siltstone at Mt Rymill (73S, 66E), Prince Charles Mountains, Antarctica, reflect the ancestral Gamburtsev Subglacial Mountains - Vostok Subglacial Highlands complex

Abstract

Clasts of red siltstone with Glossopteris from moraine around Mt Rymill in the southern Prince Charles Mountains, East Antarctica, can be traced upslope in the Lambert Graben system to the nearby Gamburtsev Subglacial Mountains (GSM). The clasts contain zircons with SHRIMP U-Pb ages of 620-460 Ma and 1300-970 Ma from host rocks of intermediate to mafic rocks, and a clay fraction with a TDM Nd model age of 2.72 Ga and eNd of -18.3, derived from upper continental crust. East of the GSM, at Lake Vostok, clasts of siltstone in accreted ice can be traced to the Vostok Subglacial Highlands (VSH). The clasts contain zircons and monazites with SHRIMP U-Pb ages (Leitchenkov et al., 2007) broadly similar to those from Mt Rymill, and a TDM Nd model age of 1.88 Ga and eNd of -15 (Delmonte et al., 2004). Other Mesozoic and Paleozoic sediments deposited in a radial pattern about central Antarctica contain detrital zircons dominated by populations aged 700-500 Ma and 1300-1000 Ma, which we interpret as reflecting a GSM-VSH provenance dominated by rocks generated during the Pan-Gondwanaland and Grenville events ofsupercontinental assembly.