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The New Guinea Limestone Group is a thick, predominantly carbonate, section covering the Bomberai Peninsula area of Irian Jaya The general depositional history of this group is indicated from studies of the stratigraphic section encountered in three wells recently drilled in this area.The Besiri River well, located in the southern Bomberai region, penetrated the Tertiary section and bottomed in Upper Cretaceous marine sediments. Petrographic and paleontologk studies indicate that the Mesozoic section is unconformably overiain by a thick Paleocene carbonate and shale interval which was deposited in midde to outerneritic shelf conditions. The Paleocene section is unconformably overlain by a thick nentic carbonate deposit of Eocene age. Unconformably upon this Eocene section is a thin Oligocene sandstone and shale interval. This OIigocene intervd is the Sirga Formation which was deposited in a middle to outer-neritic environment. Lying conformably over this ciastic interval is a thick Upper Oligocene to Middle Miocene shailow-water carbonate section. This section appears to be reefal in the lower part and a back-reef deposit in the upper portion, suggesting regression or a basinward prograding reefal envkonment. This carbonate section is unconformably overlain by the Upper Miocene to Pliocene Buru Formation which consists of claystone deposited in a bathyal environment.The Jamusura well, also located in South Bomberai. penetrated approximateIy 1000 feet of Middle llliocene New Guinea Limestone. This carbonate section consists of back-reef and outer-shelf deposits which are mconfomably overlain by the Upper Miocene to PIiocene Buru section.The Aroba well, located in the Northern Bomberai area, also tested the Upper New Guinea Limestone, penetrating approximately 250 feet of the Middle Miocene donate section. This carbonate interval is an open-shelf, near-reef deposit and is overlain by a regressive Upper Miocene to Pleistocene claystone section.Well data and limited outcrop information indicate the following depositional history for the New Guinea Limestone Group in the Bornbemi Peninsula area:PaleoceneIn the southern Bomberai area, middle to outer-neritic open-shelf cIastic and carbonate deposition took place over an unconformable Mesozoic surface.EoceneInner to middle-neritic carbonate deposition occurred. Tectonism is suggested by an Upper Eocene unconformity.OligoceneA transgressive clastic section was deposited, overlain by a shallowwater carbonate interval.Early-Middle MioceneExtensive carbonate deposition occurred with depositional environments ranging from fore-reef to reef and back-reef. Regression or regional uplift produced a Middle Miocene unconformity.Late Miocene-PleistoceneCarbonate deposition ended with an influx of dastic sediment Depositional environments ranged from paraIic and continental in the north to bathyal in the southern Bomberai area.