Petrological character of multitextured layered gabbros exposed at the Hess Deep rift

Abstract

Primitive modally-layered gabbros from the lowermost plutonic crust of a fast-spreading ridge exposed at the Hess Deep rift were firstly recovered by IODP Exp.345 on January 2013. Orthopyroxene amazingly occurs as an early crystallizing phase in the layered gabbros. Two main types of layered structures in the gabbros are simple modal layers and irregular bands. In this presentation, we will report petrographical and mineralogical characters of multitextured layered gabbros with the irregular bands (Opx-rich band, Melanocratic and leucocratic bands, etc.) and consider the origin of the bands.