Abstract

The Kromong carbonate rock is situated 20 km west of the city of Cirebon, West Java. It covers an area of 4 km 2 and occupies the northern tip of the Kromong complex which consist mostly of andesitic intrusive rocks.

The core of the Kromong anticline consists of interbedded limestones and shales containing abundant Orbitoids, Algea and plaktonic foraminifera.

It is overlain conformably by hard, thickly bedded light grey reefal limestone containing abundant algae and boring shells. Additional data on the geology and paleontology recently obtained from field observations by the authors, and furthermore correlation made with adjacent wells, confirms the occurrence of limestone belonging to the older Cibulakan formation and to the younger Parigi formation.

The age of the upper member of the Cibulakan formation is assigned as T.fl-2, whereas the Parigi limestone is T.f3 in age using the Indonesian Letter Classification. On the basis of the fossil content, the upper member of the Cibulakan formation is supposed to have been deposited in warm shallow open seas which gradually became shallower and protected toward late Miocene time.

Several intrusive bodies of andesitic and dacitic rocks of Plio-Pleistocene age penetrated these carbonates. Numerous oil and asphalt seeps were found along the faults in the northern part of this area.