Chemical and Isotopic Composition of Lavas from the Northern Mariana Trough: Implications for Magmagenesis in Back-arc Basins

Abstract

where seafloor spreading occurs, doubling to 28 8% for the We report the results of a geochemical and isotopic study of northernmost part of the rift axis. The greater degree of melting in mostly basaltic glasses recovered from 25 dredge stations along the the north reflects the greater amount of water added to the mantle northernmost 500 km of the Mariana Trough extension axis. The source, reflecting the arc-like nature of the source region and melt distribution of samples links regions of seafloor spreading to the generation style characteristic of the initial stages of back-arc basin south with regions farther north where a progression of rifting formation. Our data indicate that F = 044W+ 007, where styles accompanies the earliest stages of back-arc basin extension.