From reefs to drift: Miocene/Pliocene sedimentary change in the Browse Basin, NW Australia

本研究建议的重点是分析晚中新世-上新世和今天之间的澳大利亚西北大陆架的Browse盆地的沉积发展。这个时间间隔的特点是沉积记录的显着变化，最清楚地记录了区域衰减的热带珊瑚礁发展周围的中新世-上新世边界，这正好与电流控制的漂移沉积的发病和随后的统治。这种古环境变化的关键控制因素以前没有详细研究过。将测试以下（部分有争议的）假设：（1）盆地沉降是有差异的，并且在6 Ma左右强烈增加，最终超过珊瑚礁产量，支持水流控制的沉积作用。沉降的增加可能与研究区以北约200-500公里的澳大利亚-班达弧碰撞区的构造载荷有关，和/或与地幔对流下降控制的动态地形有关。(2)主要的海平面变化开始约6马削弱礁生长的经常性暴露和溺水，和一般高的长期沉降的盆地支持漂移沉积掩埋中新世礁。(3)澳大利亚与班达弧的碰撞限制了印度尼西亚的洋流，改变了浏览盆地的洋流状况，导致了珊瑚礁的消亡和漂流沉积的主导地位。(4)晚中新世-上新世到最近的断层和褶皱，作为澳大利亚-班达弧碰撞的远场后果，重塑了浏览盆地的形态，集中了以前被珊瑚礁覆盖的地区的强电流。

This research proposal focuses on the analysis of the sedimentary development of the Browse Basin, Australian Northwest Shelf, between the late Miocene-Pliocene and today. This time interval is characterised by significant changes in the sedimentary record, most clearly documented by a regional decay of tropical reef development around the Miocene-Pliocene boundary, which coincided with the onset and subsequent domination of current-controlled drift sedimentation. The key controls for this palaeo-environmental change have not been studied previously in detail. Following (partly controversial) hypotheses will be tested: (1) Basin subsidence was differential and strongly increased around 6 Ma, ultimately outpacing reef production supporting current-controlled sedimentation. The increase in subsidence can be related to tectonic loading at the Australia-Banda Arc collision zone ~200-500 km north of the study area, and/or to dynamic topography controlled by convective drawdown in the earth´s mantle. (2) Major eustatic variations commencing around 6 Ma weakened reef growth by recurrent exposure and drowning, and the generally high long-term subsidence of the basin supported drift deposition burying Miocene reefs. (3) The collision of Australia with the Banda Arc restricted the Indonesian Throughflow changing the ocean current regime in the Browse Basin, which led to the demise of reefs and the dominance of drift sedimentation. (4) Late Miocene-Pliocene to recent faulting and folding as a far-field consequence of the Australia-Banda Arc collision reshaped the morphology of the Browse Basin, focusing strong currents in areas previously covered by reefs.