COMPOSITION AND MASS FLUX OF SEDIMENT ENTERING THE WORLDS SUBDUCTION ZONES - IMPLICATIONS FOR GLOBAL SEDIMENT BUDGETS, GREAT EARTHQUAKES, AND VOLCANISM

Lithologic data compiled from Deep Sea Drilling Project and Ocean Dril ling Program sites, when combined with orthogonal convergence rates at convergent plate boundaries, permit quantification of the mass flux o f sediment into subduction zones. We have made such calculations for e ach major sediment component - terrigenous grains, calcium carbonate, opal, and water - for twelve trench systems. Results show that 1.4 X 1 0(15) g/yr of sediment and 0.9 X 10(15) g/yr of water enter the trench es in the oceanic sedimentary layer. Most of the entering sediment, 1. 1 X 10(15) g/yr, is terrigenous; the remainder is more carbonate than opal. For most of geologic time an order of magnitude more sediment en ters the ocean than leaves it via subduction. The global sedimentary c ycle need be in balance only over an entire Wilson cycle. Comparison o f sediment fluxes into trenches with the magnitude of large earthquake s and with the composition of bulk volcanic rock shows no correlation.