Pb Isotopes in the Southern Ocean: A Study of Pb Systematics and Continental Weathering During the Eocene/Oligocene Transition

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该奖项支持了一项研究工作，该研究利用位于南大洋的六个海洋钻探项目地点，建立了跨越“温室-冰窖”（始新世/渐新世边界）过渡的深水铅同位素记录。该项目的目标是扩大对该地区海水Pb系统的认识，以及对南极冰冻圈演化过程中大陆风化过程的认识。在系统学方面，从大块沉积物中提取的记录将允许研究水柱中铅的分层，提供有关铅输入和向深水转移的信息。此外，PI将评估南大洋输入是否是由大西洋和太平洋水团平流到盆地的铅主导，还是由当地风化内部产生的铅主导。海水和碎屑Pb同位素之间的比较也将用于评估南极冰盖生长过程中化学风化与机械风化的强度，并通过Nd同位素确定的风化脉冲进行详细评估。基于海水铅同位素交叉图的物源研究将获得有关来源区域和输入地点的信息。该奖项还将支持研究生和本科生的研究经验、当地社区的外展活动以及课堂讨论和练习的材料。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award supports a research effort to construct deep water Pb isotopic records across the "Greenhouse-icehouse" (Eocene/Oligocene boundary) transition using six Ocean Drilling Program sites located in the Southern Ocean. The project goals are to expand understanding of: 1) seawater Pb systematics in this region, and 2) continental weathering processes during the evolution of the Antarctic cryosphere. In terms of systematics, records extracted from bulk sediments will allow study of the stratification of the water column with respect to Pb, providing information about the input and transfer of Pb to deep waters. In addition, the PI will evaluate whether Southern Ocean inputs are dominated by Pb advected into the basin with water masses from the Atlantic and Pacific, or by Pb derived internally from local weathering. A comparison between seawater and detrital Pb isotopes will also be used to evaluate the intensity of chemical versus mechanical weathering during growth of the Antarctic Ice Sheet, with a detailed evaluation across a weathering pulse identified by Nd isotopes. Provenance studies based on crossplots of seawater Pb isotopes will yield information about source regions and input sites. This award will also support graduate and undergraduate research experiences, outreach activities within the local community, and material for classroom discussions and exercises.