Geological history of the dry valleys, Antarctica, based on stable isotope studies.
In 1973, DVDP 4 drilling was performed to obtain unconsolidated sediments of Lake Vanda, McMurdo oasis. The cored sediments were found to contain layered salt concretions composed of gypsum, thenardite and calcite. On the basis of stable isotope compositions, delta-C-13, delta-O-18 and delta-S-34, of the water and salts, in was concluded that the lake and the Wright Valleys were once a fjord containing sea water and isolated from the ocean by glaciation. Micropaleontological studies for the cored sediments were also performed, indicating the existence of marine fossil fragments, marine sponge microsclere and marine centric diatom, only below the 1st gravel layer. This supports the above conclusions. Other evidence suggests that the sea water level fluctuated markedly in geologic time and reached possible 150m higher than at present, and that Wright Valleys and Taylor Valleys were under ocean water in the past.
Nakai, N.; Mizutani, Y. Geological history of the dry valleys, Antarctica, based on stable isotope studies. Antarctic Recordno.58:244-2531977