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ABSTRACT: A Synthesis of Regional Elements of the Papuan Fold and Thrust Belt of Papua New Guinea

HEBBERGER, JOHN, JR., Chevron Overseas Petroleum Inc., San Ramon, CA

Several elements of the central Papuan fold and thrust belt in a 175 kilometer long salient between longitudes 143 degrees 20' and 144 degrees 40' have long been enigmatic. These include changes in Mesozoic-Cenozoic facies distribution; existence of a deep gravity minimum; existence of the Kubor Anticline; localization of oil discoveries to the salient area; and existence of the salient itself.

A synthesis which explains these features begins with development of a typical Atlantic type passive margin in Late Triassic and Early Jurassic time. During this rifting the Kubor Anticline continental fragment partially escaped to the northeast, causing development of a deep, locally restricted marine basin in the resulting salient area. Late Triassic and Jurassic mixed oil and gas source rocks were deposited in this basinal area. Sufficient expression of this basin remained to affect the depositional extent of Cretaceous to Tertiary rocks (e.g. Cretaceous Toro Sandstone, Miocene Darai Limestone). Cretaceous deposition and burial caused maturation of the Jurassic source material and migration of resulting oil and gas into passive margin traps around the margins of the basin. Complex ollision along the northern margin of New Guinea in Pliocene-Pleistocene time caused development of the Papuan fold and thrust belt, uplift and movement of the Kubor Antlicline back to the southwest partially over the basinal area creation of thrust belt structures into which this oil remigrated, and an explanation for the apparent limited lateral extent of oil in Papuan fold and thrust belt structures.

 

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)