Reviews on mantle peridotites from the Philippine Sea backarc spreading systems

Abstract

This article presents a review on mantle peridotites from the Philippine Sea backarc spreading systems. Reports of peridotite exposures in the Philippine Sea backarc spreading systems are only known in the Parece Vela Rift, the Mariana Trough, the Central Basin Fault, and the Nishi-noshima Rift. Distinct mantle processes occur beneath the Parece Vela Rift and the Mariana Trough. These are named the "Parece Vela Rift-type mantle process" and the "Mariana Trough-type mantle process", respectively. The Parece Vela Rift-type mantle process is an extraordinary process beneath a segment mid-point, basically accompanying fertile peridotite, plagioclase-bearing peridotite, and dunite. On the other hand, the Mariana Trough-type mantle process is an ordinary process at a ridge-transform intersection of a typical slow-spreading ridge, basically accompanying abundant wall-rock peridotite and subordinate impregnated peridotite with gabbroic vein. The present review shows that the Philippine Sea backarc basin peridotites are essentially undepleted and are more similar to slow-spreading ridge abyssal peridotites, and unlike peridotites from most arcs and forearcs.