Neogene uplift and deformation in the northeastern Bird’s Head Peninsula, West Papua, Indonesia: consequences of oblique plate convergence

Abstract

ABSTRACT Since ~ 25 Ma ago the plate margin between the Australian plate and the Philippine Sea and Pacific-Caroline plates in northwestern New Guinea has been undergoing oblique convergence and resulted in various uplifts and compressional deformation in the Bird’s Head Peninsula. These reflect partitioning into north-northeast compression and east-west sinistral strike-slip faulting analogous to that in the Sumatran active margin. We present new data on the provenance of the upper Miocene to lower Pliocene succession in the northeastern Bird’s Head Peninsula and its structure that has enabled a new tectonic synthesis. Initiation of oblique convergence resulted in development of the sinistral strike-slip Sorong Fault and docking of the Oligocene Arfak Volcanics from the southern Philippine Sea Plate. At ~ 15–12 Ma the compressional component initiated 40 km of dextral offset of the Sorong Fault along the northwest-trending Ransiki Fault. Subsequently, sinistral movement along the Sorong Fault was impeded by formation of a restraining bend at the Ransiki Fault, with uplift shown by the provenance of the local upper Miocene to lower Pliocene conglomerates. Further compressional deformation in the late Pliocene to Pleistocene caused widespread uplift and folding in the adjacent upper Miocene to lower Pliocene succession.