Upper Cretaceous floras of King George Island, West Antarctica, and their palaeoenvironmental and phytogeographic implications

The mega- and palynofloras that occur in the lower part of the volcanic-sed imentary succession of King George Island, northern South Shetland Islands, are of Late Campanian and probably also Early Maastrichtian age. They vary in composition locally, reflecting lateral facies changes, taphonomic proc esses and climatic differences. Those recovered from sections on the Fildes Peninsula (Half Three Point Formation, Fildes Peninsula Group) are commonl y dominated by products of ferns, mainly of the families Cyatheaceae, Dicks oniaceae and Gleicheniaceae, bur there are also fungal spores, and pollen g rains and foliage of conifers (mostly referable to the Podocarpaceae) and a ngiosperms. Sometimes the combined remains of conifers and flowering plants may, however, comprise more than 50% of assemblages. By contrast, the mega flora recovered from Admiralty Bay (Zamek Formation, Baranowski Glacier Gro up) is dominated by angiosperms. These include foliage of Nothofagus and pr imitive laurophyllous species. The vegetation that is represented mainly cl othed the eastern side of high fore-are uplands, and was affected by the vo lcanic events implied by the lithologies encountered. The floras contain el ements that are found in coeval deposits in other southern continents, the descendants of which today inhabit parts of Australia/Tasmania, New Zealand and South America. One new genus, Sterculiaephyllum, and four new species, S. australis, Ficophyllum skuaensis, Nothofagus zastawniakiae and N. glauc ifolia, are described. (C) 2000 Academic Press.