The Control of Depositional Depth, Tectonic Uplift, and Volcanism on Sedimentation Processes in the Back-Arc Basins of the Western Pacific Ocean

Abstract

Nine sediment types are recognized in cores recovered by the Deep Sea Drilling Project from back-arc basins in the western Pacific. These include submarine fan turbidites, debris flows, silty basinal turbidites, biogenic pelagic carbonate sediments, resedimented carbonates, biogenic pelagic silica sediments, pyro-clastics, hemipelagic clays, and pelagic clays. Most of these sediments were deposited independent of basinal rifting (spreading) processes. The transition from biogenic pelagic carbonate sediments into overlying pelagic clays is the only sedimentary sequence dependent on basinal tectonic processes, through post-rifting subsidence associated with heat loss. Hemipelagic clays and silty turbidites are controlled by sediment yield from continental sources and by climatic change, whereas deposition of biogenic pelagic sediments depend on ocean circulation and on latitudinally-defined productivity zones. Coarse pyroclastics are the product of local volcanic periodicity, whereas ash deposition is contr...