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

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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.