Dinoflagellate cysts from two Oligocene surface sections on Java Island, Indonesia
Morgenroth, Peter; Rahardjo, Antonius T.; Maryunani, K. Anwar
published: Mar 1, 2011
As part of a study on the stratigraphic distribution of dinoflagellate cysts in the Tertiary of Indonesia, two Oligocene surface sections in West Java have been investigated: The type section of the Batuasih Formation located near Cibadak and a section close to Padalarang. The Batuasih Formation represents a transgressional marine sequence consisting mainly of claystones deposited after the continental Eocene/Oligocene Bajah Formation. This sequence is overlain by limestones of the Rajamandala Formation. Foraminifera found by the authors and studies made on nannoplankton date the Batuasih section as Early Upper to Late Early Oligocene. Dinoflagellate cysts are abundant in phosphatic nodules, but are heavily affected by thermal metamorphism, past overheating of the section, in the claystones and sandstones. The Padalarang section consists of claystones with few thin sandstone intercalations in the upper part. Foraminifera are indicative of planktonic zones P20-P21, i. e. Early Upper to Late Early Oligocene. Dinoflagellate cysts are common and seem to indicate that this section, although within the P20-P21 zones, may represent a slightly younger interval than that exposed at Batuasih. Twenty-six dinoflagellate species have been found in both sections including three new species. Our investigations have resulted in the identification of several stratigraphic markers for the Oligocene strata in the region.