The late Miocene to Pliocene constriction of the Indonesian Gateway and its impact on ocean circulation and climate

我们的研究重点是中新世至上新世印度尼西亚门户的关闭及其对全球海洋环流和气候变化的影响。印度尼西亚门的收缩导致了现代西太平洋暖水池的形成，并将海洋环流从主要的纬向流动转变为经向流动。特别是，我们将研究印尼贯穿流在-8~~2.4 Ma期间的逐渐减少，并检验Cane和Molnar(2001)的假说，即印度尼西亚门户早期的上新世收缩可能触发了北半球冰川(NHG)的开始。根据大气环流模式，印尼环流的减少应该导致(1)印度洋表面冷却，(2)通过加强的东澳大利亚流，从热带到南大洋的经向热传输增强，以及(3)澳大利亚西侧的Leeuwin流减弱。选择了四个DSDP/ODP站来调查这些拟议的变化：来自热带东印度洋纽伦堡/铁德曼的756(214)站：印度尼西亚门户洋，Leeuwin海流下方的763站，以及东澳大利亚流影响范围内的580和1172站。通过对浮游有孔虫的Mg/Ca和51SO的联合测量，可以在时间分辨率上重建中新世/上新世时间片的海面(次表层)温度、温跃层深度和盐度，并将能够破译印度尼西亚Throughflow收缩期间的水文变化。

Our studies focus on the Miocene to Pliocene closure of the Indonesian Gateway and its impact on changes in global ocean circulation and climate. The constriction of the Indonesian Gateway led to the formation of the modern W-Pacific warm water pool and changed ocean circulation from a predominantly latitudinal to a meridional flow. In particular, we will examine the progressive reduction of the Indonesian Throughflow within the time period from -8 to ~2.4 Ma and test the hypothesis of Cane and Molnar (2001) that the early Pliocene constriction of the Indonesian Gateway might have triggered the onset of the Northern Hemisphere Glaciation (NHG). According to general circulation models, the reduction in the Indonesian Throughflow should have led to (1) a surface cooling of the Indian Ocean, (2) a strengthened meridional heat transfer from the tropics to the Southern Ocean via an intensified East Australian Current, and (3) a weakening of the Leeuwin Current on the western side of Australia. Four DSDP/ODP Sites were selected to investigate these proposed changes: Site 756 (214) from the tropical east Indian Nürnberg/Tiedemann: Indonesian Gateway Ocean, Site 763 below the Leeuwin Current, and Sites 580 and 1172 within the influence of the East Australian Current. The combined measurement of planktic foraminiferal Mg/Ca and 51SO will allow to reconstruct sea-surface (subsurface) temperatures, thermocline depth and salinities at a temporal resolution for the Miocene/Pliocene time slice not yet available, and will allow to decipher hydrographic changes during the constriction of the Indonesian Throughflow.