SOURCE-TO-SINK CONSTRAINTS ON TECTONIC AND SEDIMENTARY EVOLUTION OF THE CENTRAL RANGE, CENDERAWASIH BAY (INDONESIA) AND GULF OF PAPUA (PAPUA NEW GUINEA)
Résumé
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. Recent studies have shown that rapid subduction, uplift and
exhumation events took place in response to a fast-oblique convergence between the Pacific and the Australian
plates. 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.
One hypothesis claims 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. Alternatively, the current
configuration of Cenderawasih Bay could have resulted 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. Hence, volume balance supports the view that the embayment did
not occurred in response to a hypothetical recent (2-3 Ma) aperture of the Bay. 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. Ophiolites, volcanic arc rocks and diorites contribute minor proportions.
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/yr with a maximum SPAR of 0.23-0.58
mm/yr, and the second during the last 3 Ma, at a mean SPAR ranging between 0.93-1.62 mm/yr and with a
maximum SPAR between 2.13-3.17 mm/yr, 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-toSink systems to highlight the tectonic control
on sedimentary flux, provenance and SPAR in the Cenderawasih Bay and Gulf of Papua.