Funds are provided for field work and subsequent lab study of the tectonic and magmatic evolution of an intraoceanic arc as characterized by the SE Marina Arc rifts (SEMFR) and southernmost Marina Trough spreading center. A combined deep-tow sidescan sonar and dredging/wax-coring cruise is planned to the region. The recent discovery of volcanism in the SEMFR suggests that mantle wedge asthenosphere has been drawn into the rifts and thus the PIs hope that their volcanic products may more directly reflect variations in slab fluxes and mantle melting associated with varying P-T conditions and breakdown of hydrous minerals in the underlying slab. The regional bathymetric and geophysical data synthesis will allow the PIs to kinematically model rift evolution.
