Deciphering Oligocene Climate Dynamics

点击翻译按钮获取中文摘要

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.