Seeking Hidden Glaciations of the Greenhouse World

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The Eocene Epoch (56 to 34 million years ago) is generally thought of as a period of "greenhouse" climate conditions, but some evidence suggests that brief episodes of Antarctic glaciation may have occurred during this time. However, evidence for such glacial periods is indirect and up to now has not been firmly substantiated or characterized. This leaves significant gaps in our understanding of Eocene climate behavior, and of the processes associated with a period of profound change in Earth's history. The proposed work, led by a scientist from the University of South Carolina, will address this knowledge gap by using neodymium (Nd) and strontium (Sr) isotopic records to determine the timing, extent, and frequency of Eocene glacial events. Glacial weathering of Antarctic rocks produces detrital sediment with a unique isotopic signature, meaning that sediment produced on the Antarctic continent and deposited on the seafloor during glaciation is distinguishable within sediment cores. The project is motivated by preliminary Nd data that indicate a significant episode of Eocene glaciation ca. 37 million years ago, 3 million years earlier than previous estimates of the earliest Antarctic glaciation. To further identify and constrain glacial events in the middle to late Eocene, the proposed work will generate Nd and Sr records from Southern Ocean sediment cores collected by the Integrated Ocean Drilling Program (IODP).The datasets produced by this project will be relevant not only to understanding past Antarctic glaciation, but also to constraining low-latitude nutrient dynamics and productivity (for which glacial weathering is an important parameter). In this way, the proposed work aligns closely with the objectives of the Pacific Equatorial Age Transect (PEAT), a science program implemented by IODP. The project will involve an undergraduate and a graduate student. The project leader will also work with educators to develop Earth Science literacy programs for elementary school children.