9317307 Fisk This award supports a study of rocks from submarine volcanos and hydrothermal vents in the Bransfield Straits region of the Antarctic Peninsula. This is a continental margin rift in which volcanoes less than 1 million years old have formed on thinned continental crust from melting in the upper mantle. Prior to 4 million years ago, this region was undergoing active subduction of oceanic crust. Seismic studies of recent earthquakes in the Bransfield Strait indicate the presence of an ancient slab of oceanic crust approximately 55 to 85 kilometers beneath the surface. As a cold, wet, slab sinks into the mantle, it heats up, dehydrates, and expels fluid into the surrounding mantle. This fluid induces melting and the melts move upward; some magma is erupted at the surface. By examining the volcanic rocks in the Bransfield Strait, the investigators will learn about magmatic processes in the mantle and about processes related to recycling of oceanic crust into the mantle that occurred in the past, during active subduction. An ancillary aspect of this study relates to hydrothermal activity near the volcanoes. Hydrothermally altered volcanic rocks will be analyzed in order to determine the chemical changes that hydrothermal alteration has caused. This study utilizes rocks that have already been collected and visually characterized. ***
