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

The borehole at the southern part of subglacial Lake Vostok has been drilled into an ice layer 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 0.8−1.2 Ga and 1.6−1.8 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 MesoproterozoicNeoproterozoic crustal provinces