In 1994, a joint Japanese-American dive program utilizing the worlds deepest diving active research submersible (SHINKAI 6500) was carried out at the western ridge-transform intersection (RTI) of the Mid-Atlantic Ridge and Kane transform in the central North Atlantic Ocean. A total of 15 dives were completed along with surface-ship geophysical mapping of bathymetry, magnetic and gravity fields....

Experimental and geochemical studies were performed to understand the formation of certain terrestrial and lunar igneous rocks. Chapter one is a study of convergent margin magmatism at Medicine Lake Volcano, California. The petrogenesis of a suite of variably porphyritic, high-alumina lavas was inferred from field relations, hydrous melting experiments and geochemical modeling. I conclude that ...

Variations in the abundance of iron in the mantle may have important consequences for mantle dynamics and geochemistry. The abundance of iron in lavas derived from mantle source regions varies during partial melting and subsequent fractionation, so that source heterogeneities are not easily resolved in iron abundances alone. However, manganese is a geochemically similar element, so that the pla...

A volcanic crust may be produced as a result of magma ocean processes. Solidification of a magma ocean naturally produces a silicate mantle with denser layers near the surface, therefore unstable to gravitational overturn. The mantle is predicted to rapidly flow in the solid state to gravitational stability. Hot buoyant silicate mantle rising from depth will melt through depressurization and er...

The viscosity of lavas erupted at volcanic arcs varies over orders of magnitude. A comparison of the relative abundance of viscous lava dome eruptions indicates that the average viscosity of arc lavas also varies considerably between arcs. It is shown that for continental or transitional arcs with little within-arc crustal deformation and without underlying slab windows or tears, average lava v...

the nain and ashin ophiolites are located in northeastern isfahan province, in western central-east iranian microplate. pillow lavas are one of the most significant cretaceous rock units. the lower partial melting degree in mantle peridotites of ashin ophiolite, and the derived melt by melting their clinopyroxene caused a more basic (basalt) and enriched nature for the ashin pillow lavas, where...