Neoproterozoic Basement Control of New Guinea Deep Structure

Abstract

A regional synthesis and re-evaluation of deep crustal structure in western New Guinea shows that Neoproterozoic normal faults and transfer structures developed in Australian plate crystalline basement have been reactivated to control the location and orientation of ductile brittle structures formed during the Central Range Orogeny. The island of New Guinea is the emergent part of one of the most tectonically complex places on the Earth's surface. Three major plates and more than a half dozen microplates interact in a continent-ocean collision zone that has been evolving since the Oligocene. Although the collision zone in western New Guinea is predominately east-west, northeast-trending fault structures are prominent. Of these, the Gauttier Offset can be traced from the Gauttier Mountains in northern Papua province of Indonesia south to the Mapenduma Anticline. Comparison with Neoproterozoic basement structures developed in the Arafura Sea north of Australia, and the strike and location of basement lows in new reflection seismic maps of Neoproterozoic basement south of New Guinea, indicate that the Gauttier Offset is likely to be a reactivated Neoproterozoic extensional fault. Neoproterozoic extensional faults in the Arafura Sea show extension-polarity domains bound by east-west transfer structures. Similar structural relationships may be inferred in New Guinea associated with the Gauttier Offset and other parallel structures, but controlling more recent west-northwest-striking strike-slip faults. The intersection between west-northwest-striking faults and the Gauttier Offset appears to control the location of Pliocene magmatism and mineralisation. Northeast trending faults and alignments are evident in Papua Province east and west of the Gauttier Offset structure, and in Papua New Guinea. Given a possible Neoproterozoic control, these structures are likely to control east-west variation in Mesozoic and younger stratigraphic thickness, and the location and depth of pre-Mesozoic basins, with implications for development of petroleum source rocks and reservoirs. Recognition of Neoproterozoic basement control in Cenozoic structural evolution represents a first order re-evaluation of the deep structure of New Guinea.

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