A History of Extensional, Compressional, Foreland and Now Extensional Tectonics in South Eastern Papua New Guinea

Abstract

The Papuan peninsula is 500 km long and 90–180 km a cross. A central mountain range, Owen Stanley Range, runs the length of the peninsula with lesser ranges on both sides; the great stratovolcanoes Lamington and Victory stand off on the northeast side. The three main components of peninsula surface geology are a core of metamorphic rocks forming the Owen Stanley Range, a major ophiolite complex, the PUB ophiolite, on the northeast side and accreted terranes of Cretaceous and younger sediments, volcanics and intrusive rocks on the southwest side. Modern offshore seismic data can be used to infer a fourth and subsea unit of continental crust with possible sediments as old as Permian further to the south west. The tectonic boundaries of the southeastern part of the Papuan peninsula are poorly constrained due mainly to the obduction of island arc rocks (East Papuan Composite Terrane EPCT) providing a zone of cover over continental crust (North Coral Sea Plate NCSP). Structural mapping from new offshore seismic data is utilized to push the northern boundary of the NCSP further north than previously thought. When used in conjunction with regional onshore geological mapping, which shows extensional structures, further inferences can be made on the location of the northern margin of the NSCP. The Mesozoic sedimentary rocks of the Torres Basin are thought to extend as far north as least as far a the Dayman Massif, that is at least 50 kilometres frpom the southern coast line of the Papuan Peninsula. The importance of this is to define the available rock volume within the Mesozoic Torres Basin where there may be both source and reservoir rocks and consequently a petroleum system.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015