(Table T1) Granulometry of sediments from ODP Leg 168 sites@en

Sedimentary deposits of Cascadia Basin lap onto the Juan de Fuca Ridge to within 20 km of the spreading axis (Davis and Currie, 1993, doi:10.1139/e93-023). Collectively, these interbeds of hemipelagic mud, mud turbidites, silt turbidites, sand turbidites, and debris-flow deposits act as a relatively low-permeability barrier that inhibits the hydrothermal connection between underlying igneous crust and the overlying reservoir of ocean water. The primary purpose of Leg 168 of the Ocean Drilling Program (ODP) was to explore the causes and consequences of ridge-flank hydrothermal circulation (Shipboard Scientific Party, 1997c, doi:10.2973/odp.proc.ir.168.101.1997). One important aspect of this overall goal was to determine how changes in thickness of the sediment cover affect heat flow, fluid flow, fluid composition, and chemical alteration of the igneous crust. Fluid circulation through the sediment is influenced by a variety of textural parameters and intrinsic physical properties. Physical properties of sediments usually change in a predictable way with increasing depth and mechanical compaction, but different lithologies display different compaction gradients. […]