Volatiles in magmas from the East Scotia Sea, South Atlantic Ocean

Abstract

Water plays a significant role in the phase relations of the sources of arc and back-arc lavas, and water-rich fluids ultimately derived from downgoing slabs are widely believed to influence the compositions of these sources. We recently demonstrated in a study of glasses from the Mariana trough (Stolper and Newman, 1994) how covariations in the concentrations of water and a wide range of other elements can be used to constrain the composition of a water-rich component in the sources of back-arc magmas and the influence of this component on melting. In this study we extend this approach to glasses from the Scotia Sea back-arc basin and compare the results with our previous results for the Mariana trough. The Scotia Sea provides a useful comparison because it is simpler tectonically than the Mariana trough, having experienced only one episode of back-arc spreading.

Files

Additional details