This project will examine the trace element and isotopic (radiogenic and stable) characteristics of stratigraphically- controlled Ascension Island volcanics to establish the magnitude of variations in incompatible trace-element and isotopic ratios, in order to determine mixing relationships between ocean island basalt (OIB) source components, and the origin of OIB. The voluminous pyroclastics on Ascension are as yet uncharacterized; the PIs will undertake a detailed study of the volcanology, petrology and geochemistry of the pyroclastics in relation to the lava flows and the overall magmatic evolution of the island. As the trace element and isotopic characteristics of Ascension volcanics appear to be typical of the majority of OIB, it is important to fully assess the petrogenesis and origin of this OIB type.
