Abstract

Foraminiferal and lithologic characteristics of sediments from 14 Deep Sea Research Vessel Alvin push cores have been used to investigate modern sedimentary processes in Wilmington and South Heyes submarine canyons. A nearly ubiquitous occurrence of abundant foraminiferal species is over-printed by depth-related variations in abundance. Most species are native to lower bathyal and abyssal depths and are in situ. The occurrence of neritic species is attributed to erosion of material from slump blocks of neritic origin which now comprise the steep and undercut walls of Wilmington Canyon. In Wilmington Canyon, the consistent distribution of foraminifera contrasts with marked variations in lithologic characteristics observed at channel meanders. These variations are attributed to relatively minor mass-wasting processes and to effects of bottom (perhaps tidal) and/or low density current action, more active at constrictions and along the steep walls of meanders. These processes are less prevalent in South Heyes Canyon as indicated by markedly lower compositional variations, a low percent of clastic material, and a lower rate of sediment accumulation. This is, in part, a function of the linear morphology and less varied relief of South Heyes Canyon. There is no firm evidence for prevalent high energy downslope transportation events (i.e., erosive high-density turbidity currents) in either Wilmington and South Heyes Canyons during the past 200-400 years represented by the cored material.

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