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》(公法111-5)资助的。该奖项支持一项研究工作，即利用位于南大洋的六个大洋钻探计划地点，在“温室-冰库”(始新世/渐新世界线)过渡期间建立深水铅同位素记录。该项目的目标是扩大对以下方面的了解：1)该地区的海水铅系统学，以及2)南极冰冻圈演化过程中的大陆风化过程。在系统学方面，从大块沉积物中提取的记录将有助于研究水柱相对于铅的分层，提供关于铅输入和转移到深水的信息。此外，PI将评估南大洋的输入是由来自大西洋和太平洋的水团平流进入盆地的铅主导的，还是由来自当地风化的内部铅主导的。海水和碎屑铅同位素之间的比较也将被用来评估南极冰盖生长过程中化学风化和机械风化的强度，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会图的来源研究将提供有关来源地区和输入地点的信息。该奖项还将支持研究生和本科生的研究经验，在当地社区内的外联活动，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.