Composition of Eocene-Oligocene sediments from the Kerguelen Plateau, Southern Ocean

Probably, some glaciers reached the sea, while most of the continent remained under the influence of a humid and warm to temperate climate. The growth of the inland ice resulted in enhanced physical weathering and in increased contents of detrital chlorite and kaolinite from about 40 Ma. A strengthening of the glacial conditions and the onset of continental East Antarctic glaciation is recorded in early Oligocene sediments with an age of 36 Ma.

All major sediment parameters document this event. The clay mineralogy changed between c. 36.3 Ma and c. 35.5 Ma from smectite-dominated assemblages to illite- and chlorite-dominated assemblages, the latter being indicative of physical weathering under cooler climates. Large quantities of ice-rafted gravel and sand accumulated on the Kerguelen Plateau between 36.0 Ma and 35.8 Ma.

At the same time, an increase in opal content occurred as well as a decrease in carbonate. The sediment parameters imply that the East Antarctic continent was more or less totally buried beneath the ice during Oligocene time. The ice sheet, however, probably did not have a polar but a temperate character, as indicated by the occurrence of Nothofagus and relatively warm surface water temperatures prohibiting the long-distance transport of debris by icebergs.