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The Pulau Seribu patch-reef complex, located 50 km northwest of Jakarta, is elliptical in plan view, measuring 40 km north-south and 12 km east-west. Individual reefs range in length from 50 m to over 6 km, show a strong east-west lineation due to seasonal winds and currents, and grow up into the intertidal zone.

Facies mapping (based on 250 bottom samples and Landsat image analysis) shows the extent of reef-crest, reef-flat, beach, island, reef-slope, and lagoonal facies. The reef crest is fairly narrow, flat, continuous along strike, and consists of coral-algal boundstones. The reef framework of predominately platy and branching corals is infilled with coral-skeletal packstones and wackestones and represents a small percentage of reef-related facies developed in the reef complex, being overshadowed by extensive reef flats of coral-skeletal packstones. Commonly, beach and island facies of coral-skeletal grainstones occur near the center of individual patch reefs. In front of the reef crest, an apron of reef-derived coral-skeletal packstones is deposited as reef-slope facies. This grades downd p into lagoonal facies of highly burrowed molluscan foraminiferal wackestone and packstone and coral molluscan wackestone and packstone, both with low TOC values that indicate no source rock potential.

Pulau Seribu is an important lithofacies model for better understanding Tertiary reefs in Indonesia, especially the prolific hydrocarbon reservoirs of northern Sumatra.

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