Marine transgressions on the Pleistocene Pecangan Formation in the Sangiran area, central Java, Indonesia

Abstract

Sangiran in central Jawa, Indonesia, is very famous for the occurrence of the fossil bones of Pithecanthropus erectus. The Pleistocene sediment at Sangiran area is divided into two formations; Kabuh Formation of volcanic material and Pecangan Formation of mainly clays with some diatomites, thin volcanic ashes and thick pyroclastic flow-deposits. About a hundred samples were taken from muddy beds of the Pecangan Formation for paleomagnetic measurements, diatom analysis and electric conductivity measurement. Nineteeen of them contain fossil diatoms. As the results of diatom analysis and electric conductivity measurements, four marine transgressions are found in the Pecangan Formation. The first major transgression took place after the Olduvai Event and the next one just before the Jaramillo Event. The latter can be correlated with that of the Ma0 Marine Clay Bed in the Osaka area in Japan. The results of the work indicate that the age of the marine transgression in the east Pacific areas reflects the glacial eustasy.