Hess Deep Rift Valley

Abstract

The principal success of Leg 147 was the recovery of continuous sections of crustal gabbroic rocks and shallow mantle harzburgite, dunite, and intercalated gabbroic rocks from the Hess Deep. These cored crustal sections at Site 894 were generated at the fast-spreading East Pacific Rise (EPR), approximately 1 Ma. Hess Deep is the deepest part of a westward-propagating rift valley that is opening up the eastern flank of the equatorial EPR in advance of the propagating Cocos-Nazca spreading center. The exposures cored at Sites 894 and 895 were located on the crest and southern slope of an intra-rift ridge, respectively. -Authors