This grant will fund a 3 year study of the genesis of the oceanic crust at spreading ridges, based on evidence from the mantle and lower crust of a thrust slice of oceanic crust and upper mantle in Oman. Our main objectives are to constrain (1) porous flow and/or fracture mechanisms of melt extraction from the mantle, and (2) formation of the igneous lower oceanic crust via combinations of two end-member possibilities: (a) crystallization in a single magma chamber plus ductile flow downward and outward to form the lower crust, and (b) crystallization of lower crustal plutonic rocks in many small magma chambers close to their current depth of emplacement. In addition, we seek to address related questions concerning (3) melt extraction mechanisms in the lower crust, (4) deformation mechanisms and strain partitioning in the lower crust, and (5) igneous cooling and crystallization rates beneath the axis of an oceanic spreading ridge.
