Source-to-Sink constraints on tectonic and sedimentary evolution of the Central Range, Cenderawasih Bay (Indonesia) and Gulf of Papua (Papua New Guinea)

Abstract

The island of Papua New Guinea is the result of continent-arc collision that began building the island¿s Central Range during the late Miocene. The tectono-sedimentary evolution of the Cenderawasih Bay, in the northwestern part of the island of Papua New Guinea (Indonesia), which links the Kepala Burung block to the Central Range is still poorly understood. Previous studies have shown that this bay contains a thick (> 8 km) sequence of undated sediments. Hypothesis claim that the embayment resulted from a 3 Ma aperture created by anticlockwise rotation of the Kepala Burung block with respect to the northern rim of the Australian plate, or from the southwest drift of a slice of volcanics/oceanic crust between 8 and 6 Ma. Using a source-to-sink approach, based on i) a geomorphologic analysis of the drainage network dynamics, ii) a reassessment of available thermochronological data, and iii) seismic lines interpretation, we suggest that sediments started to accumulate in the Cenderawasih Bay and onshore in the Waipoga Basin in the late Miocene since the beginning of the Central Range building at 12 Ma, resulting in sediment accumulation of up to 12200 m. At first order, we predict that infilling is mainly composed of siliciclastics sourced in the graphite-bearing Ruffaer Metamorphic Belt and its equivalent in the Weyland Overthrust. From the unroofing paths in the Central Range we deduce two rates of solid phase accumulation (SPAR) since 12 Ma, the first one at a mean SPAR ranging between 0.12-0.25 mm/a with a maximum SPAR of 0.23-0.58 mm/a, and the second during the last 3 Ma, at a mean SPAR ranging between 0.93-1.62 mm/a and with a maximum SPAR between 2.13-3.17 mm/a, i.e., 6700-10000 m of Plio-Pleistocene sediment accumulation. Local transtensional tectonics may explain these unusually high rates of sedimentation in an overall sinistral oblique convergence setting. We further extended this approach to the Gulf of Papua (Papua New Guinea), a foreland basin developed in the passive margin of the Coral Sea and fed by the Papuan fold-and-thrust belt and Aure fold-and-thrust belt. We compare these two source-to-sink systems to highlight the tectonic control on sedimentary flux, provenance and SPAR in the Cenderawasih Bay and Gulf of Papua.