Structural Restoration and Deformation History of the Bunguran and Sabah Fold-Thrust Belts, NW Borneo

Abstract

Summary The Neogene depositional system along the NW Borneo margin contains a number of world-class hydrocarbon provinces. Underlying the different sedimentary fills of variable thicknesses in these basins, the basement is formed predominantly by strongly to moderately attenuate continental crust, which is segmented by a number of lineaments such as the Lupar Line — Adang Fault (“Trans Borneo Shear”), West Baram Line — Sankulirang Fault systems, and others. These long-lived suture lines played a significant role in the development of the NW Borneo depocentres with sediments sourced from the Borneo hinterland. The South China Sea was developed from magma-poor rifting in response to seafloor spreading, and subsequently strike-slip faulting during the Palaeogene and continued to the Late Miocene and Pliocene, with failed subduction progressively occurring from the south-west to the north-east. The Bunguran and Sabah Fold-Thrust Belts (FTBs) are two demonstrated deformation features resulting from the complex interplay between gravity-driven deformation and episodic regional thin-skinned compression driven by South China Sea tectonics along the margin.