Deciphering Oligocene Climate Dynamics

南极冰盖是地球气候系统的重要组成部分，了解南极冰盖的演化对于评估和量化南极冰川形成以来(~40 Ma)海洋环流和太平洋赤道上升流强度的变化具有重要意义。我们的项目旨在破译建议的“一冷极”世界的渐新世冰川事件(冰川与冰川消融)的模式、速度和幅度，以破译从中东太平洋(CEPO)到亚轨道时间尺度的渐新世气候动力学及其对赤道古生产力的影响。该项目的主要重点将是环境/气候末端成员代表、中渐新世Oi-2b最大冰川事件(~27 Ma)和晚渐新世Oi-2c冰川事件(~24 Ma)，使用来自IODP考察320/321(太平洋赤道时代断面)的新材料。方法将包括利用底栖有孔虫和浮游有孔虫的氧和碳同位素以及微量元素地球化学(镁/钙比)相结合的方法，分别重建底层水温和计算冰量和海平面变化。此外，底栖有孔虫的累积率和表层和底栖底栖有孔虫的Δδ13C以及底栖和浮游有孔虫的Δδ13C将被用来评估太平洋的赤道上升流和海洋层化的强度，太平洋是地球上最大的水、热、营养和二氧化碳储存库。

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.