Marine geology of the Hess Rise: 1. Bathymetry, surface sediment distribution, and environment of deposition

摘要: New charts of bathymetry, acoustic character, and sediment distribution describe the Hess Rise, a large oceanic plateau in central north Pacific. Discrete physiographic provinces on Rise are High Plateau, shallower than 3900 m, trending N30/sup 0/W; Northeastern Flank, smooth, gentle slope gradually increasing depth to northeast; Woollard Abyssal Plain, extending farther Volcanic Province with its high peaks ridges along southern margin Rise; Mendocino Fracture Zone south, expressed by broad, planar seafloor regions bordered scarps; Western Steps, formed structural benches western side Emperor Deep, between rise Seamounts. Five types units have been mapped interpreted: transparent layer, predominantly biosiliceous pelagic clay; stratified nannofossil ooze; diffuse layer debris flows that seem originated mostly Province; an opaque horizon commonly volcaniclastic sediments usually found Zone; hyperbolic horizon, indicating outcrops igneous rock. The pronounced effect bottom currents onmore » present-day environment deposition is evidenced presence which interpreted as erosion surface, current moating, abrupt thinning surface layers truncation subbottom reflectors. widespread attributed flow Antarctic water.« less