Deciphering Oligocene Climate Dynamics

了解南极冰盖作为地球气候系统的重要组成部分的演变，对于评估和量化始新世晚期（~40 Ma）南极冰川开始以来海洋环流和太平洋赤道上升流强度的变化至关重要。我们的项目旨在破译渐新世冰川事件（冰川与去冰川）的模式、速度和幅度，以破译渐新世气候的动态以及来自中、东太平洋（CEPO）的轨道到亚轨道时间尺度对赤道古生产力的影响。项目将利用IODP远征320/321（太平洋赤道时代样带）的新材料，重点研究环境/气候端元代表，中渐新世Oi-2b最大冰川事件（~27 Ma）和弱晚渐新世Oi-2c冰川事件（~24 Ma）。方法将包括结合底栖生物和浮游有孔虫的氧和碳同位素以及微量元素地球化学（Mg/Ca比）的方法，分别用于重建底部水温和计算冰体积和海平面变化。此外，底栖有孔虫的积累速率、外栖和水生底栖有孔虫的Δδ13C以及底栖和浮游有孔虫的Δδ13C将用于评估太平洋赤道上升流的强度和海洋分层，太平洋是地球上最大的水、热、养分和二氧化碳储存库。

Understanding the evolution of the Antarctic ice-sheet, as a crucial component of Earth’s climate system, is fundamental to assess and quantify changes in ocean circulation and intensity of Pacific equatorial upwelling since the initiation of Antarctic glaciation during the late Eocene (~40 Ma). Our project aims at deciphering the mode, tempo, and amplitude of Oligocene glaciation events (glaciation vs. deglaciation) of the suggested “one cold pole” world to decipher the dynamics of Oligocene climate and the impact on equatorial paleoproductivity at orbital to suborbital time-scales from the Central Eastern Pacific Ocean (CEPO). The main focus of the project will be on the environmental/climate end-member representatives, the mid Oligocene Oi-2b maximum glaciation event (~27 Ma) and the weak late Oligocene Oi-2c glaciation event (~24 Ma), using new material from IODP Expeditions 320/321 (Pacific Equatorial Age Transect). Methods will include a combined approach of benthic and planktic foraminifera oxygen and carbon isotopes and trace element geochemistry (Mg/Ca ratios) for reconstructing bottom water temperatures and for calculating ice volume and sea level changes, respectively. In addition, benthic foraminifera accumulation rates and the Δδ13C of epi- and infaunal benthic foraminifera and Δδ13C of benthic and planktic foraminifera will be used to assess the strength of the equatorial upwelling and the ocean stratification in the Pacific ocean, the largest water, heat, nutrients, and CO2 reservoir on Earth.