Kokkolity zlepieńca pektenowego wyspy King George, Antarktyka Zachodnia

Abstract

COCCOLITHS IN THE PECTEN CONGLOMERATE FROM THE KING GEORGE ISLAND Summary The Pecten Conglomerate is a characteristic unit in the Cainozoic sequence of Antarctica (2, 4, 18, 23, 25, 28). The age of these fossiliferous strata is still controversal, as they were dated at the Pliocene (2, 4 - 6, 16) or Pleistocene (12, 18, 28). Recently an assemblage of the Oligocene coccoliths has been found (14) in glacio-marine strata of the Pecten Conglomerate (= Low Head Member of the Polonez Cove Formation) of King George Island, South Shetland Islands (Figs 1 - 3). The occurrence of the species Chiasmolithus altus Bukry & Percival, Reticulofenestra bisecta (Hay, Mohler & Wade) and Reticulofenestra umbilica (Levin) in the recognized nannofossil assemblage (Fig. 4), indicates the Oligocene age of the Low Head Member and that these strata are older than it was hitherto assumed (see: 3 - 6, 15, 16). This age is in consistent with the results of radiometric datings, which showed that rocks of the Low Head Member are older than 23 Ma (9). 1t should be noted that the facies development of the Pecten Conglomerate may have been diachroneous across the circum-Antractic Ocean during Late Paleogene - Neogene epochs. The study was supported by the Polish Academy of Sciences (Research Project MR.1.29) and the Alexander von Humboldt Foundation (Bonn).