Insight into the geology of the East Antarctic hinterland: a study of sediment inclusions from ice cores of the Lake Vostok borehole

Abstract

The borehole at the southern par t of subglacial Lake Vostok has been drilled into an ice lay er that has been refrozen from the lake water. This ice layer contains random sediment inclusions, eight of which have been studied using state-of the-art analytical techniques. Six inclusions comprise soft aggregates consisting mainly of clay-mica minerals and micron-sized quartz grains while two others are solid clasts of fine-grained cemented rocks. The largest rock clast consists of poorly-rounded quartz and minor amounts of accessory minerals and is classified as quartzose siltstone. More than twenty grains of zircon and monazite have been identified in this siltstone and dated by SIMS SHRIMP-II. Two age clusters have been recognized for these detrital grains, in the ranges 0.81.2 Ga and 1.61.8 Ga. The compositions of the rock clasts suggest that the bedrock situated to the west of Lake Vostok is sedimentary. The age data on the detrital accessory minerals suggest that the provenance of these sedimentary rocks the Gamburtsev Mountains and Vostok Subglacial Highlands, is mainly represented by Paleoproterozoic and Mesoproterozoic- Neoproterozoic crustal provinces. Citation: Leitchenkov G.L., B.V. Belyatsky, N.V. Rodionov and S.A.and Sergeev (2007), Insight into the geology of the East Antarctic hinterland: study of sediment inclusions from ice cores of the Lake Vostok borehole, in Antarctica: A Keystone in a Changing World - Online Proceedings of the 10th ISAES, edited by A. K. Cooper and C. R. Raymond et al., USGS Open-File Report 2007-1047, Short Research Paper 014, 4 p.; doi:10.3133/of2007-1047.srp014.