Neogene Structural History of Biak and the Biak Basin, Eastern Indonesia

Abstract:

The Biak Basin is within a frontier region, located between the islands of Biak to the north and Yapen to the south in the Indonesian province of West Papua. The Biak Basin is underlain by a Paleogene basement sequence that originated in an intra-oceanic island arc, formed on the leading edge of the oceanic Pacific-Caroline Plate. The basin has a structural history that can be divided into three stages: 1) a compressional stage, 2) a rifting stage and 3) a strike-slip stage.
The compressional stage occurred during the Early Miocene. Collision of the arc with the northern edge of the Australian continental margin caused folding and thrusting of the basement sequence which was uplifted and subaerially exposed resulting in a widespread unconformity that can be traced west through the western Bird’s Head as far as Halmahera.

Following this collision the Biak Basin was filled largely by carbonates from the Early Miocene. During the Middle-Late Miocene the Biak Basin underwent a period of rapid subsidence resulting from a period of rifting. Extension occurred as convergence of the Pacific Plate with the Australian margin produced a regional stress field in which the maximum compressive stress was orientated NE-SW and maximum tensional stress NW-SE. This tensional stress produced NE-SW striking horsts and grabens with a Paleogene basement overlain by Lower Miocene carbonates.

A final stage involving strike-slip faulting occurred during the Pliocene-Pleistocene with the initiation of major regional faults such as those of the Yapen Fault Zone and Biak Array which bound the southern and northeastern margins of the basin respectively. The strike-slip faulting accommodated continued convergence between the Pacific and Australian plates and uplifted Miocene carbonates as pop-up structures now observed on Biak.
There are parallels to the Biak Basin in basins within the Basin and Range Province of the western United States, in particular the Walker Lake Basin, Nevada and other triangular shaped basins along the Panamint Valley, California. These basins share many similarities including being bounded by NW-SE trending dextral strike-slip faults, E-W trending sinistral strike-slip faults and NE-SW trending extensional structures.