Seeking Hidden Glaciations of the Greenhouse World

始新世（5600万至3400万年前）通常被认为是一个“温室”气候条件的时期，但一些证据表明，在此期间可能发生过短暂的南极冰川作用。然而，这种冰期的证据是间接的，到目前为止还没有得到确切的证实或描述。这给我们对始新世气候行为的理解以及与地球历史上一个深刻变化时期相关的过程留下了重大空白。由南卡罗来纳大学的一位科学家领导的这项工作将通过使用钕（Nd）和锶（Sr）同位素记录来确定始新世冰川事件的时间、范围和频率，从而解决这一知识差距。南极岩石的冰川风化作用产生的碎屑沉积物具有独特的同位素特征，这意味着在南极大陆产生并在冰川时期沉积在海底的沉积物在沉积物岩心中是可区分的。这个项目是由初步的Nd数据推动的，这些数据表明始新世冰期的重要时期大约在3700万年前，比以前估计的最早的南极冰期早300万年。为了进一步确定和限制始新世中晚期的冰川事件，建议的工作将从综合海洋钻探计划（IODP）收集的南大洋沉积物岩心中生成Nd和Sr记录。该项目产生的数据集不仅与了解过去的南极冰川有关，而且与限制低纬度营养动态和生产力（冰川风化是一个重要参数）有关。这样，拟议的工作与太平洋赤道时代样带（PEAT）的目标密切一致，PEAT是IODP实施的一项科学计划。该项目将涉及一名本科生和一名研究生。项目负责人还将与教育工作者合作，为小学生开发地球科学素养课程。

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.