H_2O and Cl in basalts from Lau back-arc basin

Abstract

The subduction influence (fluid mobile elements) in basalts along the back arc Eastern Lau Spreading Center (ELSC) increases in several sharp gradients as the distance to the Tofua volcanic arc diminishes from 100 km in the north (19°S) to 40 km in the south (23°S). The six tectonic segments of ELSC display mixing relationships in trace element and isotopic ratios in which one end member is a subduction component that is distinctive for each segment. Basalts from the three well-sampled northern segments (ELSC-1, -2, and -3, from 19.2-20.7°S) are best for the study of volatiles because most did not lose H_2O by degassing, and because they display a wide range of H_2O/ element values on a local scale: from MORB-like to much higher values.

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