CHANGES OF SEDIMENTARY ENVIRONMENT SINCE THE LATE PLEISTOCENE IN VESTFOLD HILLS AREA, ANTARCTICA

Abstract

The Vestfold Hills area was a shallow-sea sedimentary environment in the interglacial stage (50,000—25,000 yr B.P.) of the last glacial period of the Late Pleistocene, and later became a glaciofluvial environment. This marine sedimentary plain was covered by glaciers at the time of 31,000—11,000 yr B.P. After the last glacial period (6500—3500 yr B.P.), the retreat of ice sheets in this area resulted in the formation of lakes and lagoons, followed by alternating sedimentation of three-times sub-turbidity current and two-times ice-melt water. Sulphate-Glauber salt was deposited in the inland depressions. The advance of the ice sheets in this area during the neo-ice age (2800 yr B.P.) resulted in three parallel moraine terraces consisting of boulders and coarse sands composed mainly of hornblende, and subordinately of garnet and magnetite. During this period a Si-AL-chloride detrital weathering crust was developed on hyperthenite with schistose actinolite. In addition to physical weathering (e.g. frost weathering), chemical weathering was obbviously strong.