A reassessment of the age of the Cockburn Island Formation, northern Antarctic Peninsula, and its palaeoclimatic implications

Abstract

New constraints on the age of the Cockburn Island Formation, northern Antarctic Peninsula, resulting from whole rock laser-stepped heated 40 Ar– 39 Ar dating of associated basalt and palaeomagnetic re-calibration of the ranges of the formation’s fossil diatom taxa, suggest that interglacial conditions existed around 3 million years ago. The refined age of the deposit supports continent-wide Late Pliocene warming in Antarctica, and makes more likely the occurrence of extensive marine incursions in East Antarctica at that time.