A COLLABORATIVE, STRATIGRAPHICALLY CONTROLLED GEOCHEMICAL AND ISOTOPIC STUDY OF SOUTH ATLANTIC OCEAN ISLAND VOLCANISM

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This project is a comprehensive geochemical study of volcanism on the island of Saint Helena in the South Atlantic Ocean. The volcanic rocks of this island are representative of a chemically distinctive end-member among ocean island basalts (OIB), and it is planned to fully characterize the trace element and isotope geochemistry of these basalts by analysis of stratigraphically controlled samples. Ratios among Sr, Nd, and Pb isotope analyses, combined with major and trace element determinations, will be used to quantify mixing relationships and ultimately to identify mantle sources for these basalts. This should help identify the end-member mantle components which are responsible for the chemical heterogeneity of OIB. Major and trace element geochemistry will be carried out be Weaver at the University of Oklahoma, radiogenic isotope geochemistry be Zindler at Lamont- Doherty Geological Observatory, and stable isotope geochemistry by Harmon at the NERC Isotope Geology Centre in the UK.