Deformation feature and tectonic model of the Timor Trough: New interpretation of the evolution and mechanism of Banda arc-continent collision

Abstract

The deformation of the Timor Trough is controlled by the combined dynamics of Australian Plate subduction and the arc–continent collision between Australian continent and Banda arc, and its development remains controversial. Based on the seismic, earthquake, and well datasets, we focus on these controversial problems and analyzed the deformation features and mechanism of the Timor Trough, and we established a tectonic model to discuss the arc–continent collision evolution and plate coupling. Our results and model suggest that the subsidence of the Timor Trough and uplift of the Timor Island begin at ∼3.3 Ma and marked the deformation of the Australian northwestern continental margin. We propose that the arc–continent collision underwent two phases and transformed the subduction zone into collision zone. The earliest phase uplifted and closed the forearc basin since ∼6 Ma, and the second phase of regional deformations at ∼3.3 Ma is represented by the development of backarc thrust, the cessation of volcanism, the uplift of Banda arc, and the subsidence of Timor Trough. The tearing oceanic crust provides a window for the development of backarc thrust to the southeastward. The outer and inner Banda arcs may have become a cohesive block after the collision; consequently, it is possible for them to move northward as a whole along the backarc thrust.