Collaborative Research: Using Melt Inclusions to Unravel Lithospheric Mantle and Crustal Contributions to Gondwana Flood Basalts and to Determine Pre-Eruptive Volatile Contents

Oregon State University, Corvallis OR

Investigators

Abstract

This project will use melt inclusions as a window into the earlier stages of the melt aggregation and crustal assimilation processes in magmatic plumbing systems beneath the main Gondwana flood basalt provinces (Parana, Etendeka, Karoo, Ferrar). Homogenized melt inclusions will be analysed by electron-microprobe (major elements; volatiles - Cl, F, S), laser ablation ICP-MS and MC-ICP-MS (trace elements; Pb isotopes), and ion-probe (H2O, CO2). The principal objectives are two-fold: (1) to use the diversity of compositions recorded in melt inclusions from the least crustally-contaminated samples to see whether they preserve evidence of earlier, less-contaminated magmas that might better constrain source compositions and whether these sources are in the lithospheric or sub-lithospheric mantle. (2) to obtain data on the pre-eruption volatile contents of flood basalt melts as an indicator of source characteristics, and volatile saturation pressures will also provide a unique means to determine the pressures at which melts are contaminated and aggregate and thus provide new insight into the architecture of flood basalt magma plumbing systems. The melt inclusion data will provide a means by which to estimate volatile emissions during lava eruptions and should aid the understanding of the processes responsible for the local and global environmental consequences of the eruption of such huge quantities of magma in a relatively short time interval. These results will be of interest to a broad range of scientists, including those involved in palaeoclimate studies and the modelling of the possible causes of global climate change. The project will support and enhance the geochemical laboratories at Oregon State University.