Structural Styles of Aure Complex Fold-Thrust Belt, Papua New Guinea: A Revelation of Relationship between Basin Evolution and Subsequent Deformation

The island of New Guinea ，which is arguably one of the most tectonically complex regions in the world，is evolving within the obliquely and rapidly converging Australian and Pacific plate boundary zone. The Aure complex fold-thrust belt and Aure foreland basin located in the eastern Gulf of Papua, Papua New Guinea, formed during middle Miocene-Recent. And their structural styles and evolution were not well revealed. The arcuate Aure fold-thrust belt and Aure foreland basin along the southwestern coast and offshore areas of the Papuan peninsula extend for 480 km, which can be divided into two parts, the west subbasin (WSB) and the east subbasin (ESB), and the tectonic direction changes from NW to near EW from WSB to ESB. To reveal structural styles, age of convergent and differences of WSB and ESB, we integrate the results of 42,000 km of 2D seismic reflection data, a small area of 3D seismic data, with drillings and geological maps. Where the strata were involved in the fold-thrust belt and onlap filled in the southern slope belt precisely shows the foreland basin formed in the middle Miocene. But the ESB, probably formed later in late Miocene or early Pliocene. The Aure fold-thrust belt is a typical slipping nappe structure belts with imbricate recoil faults and "s" fold, and the thrust faults have been active for many episodes. However, there are differences between the WSB and ESB: In the WSB, the strata are thicker and the fold thrust belt is wider than that of the ESB. The thrust activity of the WSB might be weakened in the pleistocene, depositing thick undeformed or weakly deformed strata, but the ESB was not. Therefore, we propose an oblique subduction model to describe the formation of the Aure foreland basin. Moreover, the Aure foreland basin has the characteristics of multiple active periods, the continuous denudation of the western orogenic belt provides a continuous source of material for the Aure foreland basin especially the WSB.