Sediment-sea-water interaction at 200 and 300^oC, 500 bars pressure: the role of sediment composition in diagenesis and low- grade metamorphism of marine clay.

The development of acidity is attributed to the formation of smectite, whereas the oxidation state of the fluids was dependent on the relative proportions of ferromanganese oxide phase, ferrous-rich silicate phases, and organic carbon. Silica concentrations in the experimental fluids ranged from cristobalite to amorphous silica saturation levels in response to the dissolution of amorphous silica. Comparison of fluid data and mineralogical assemblages from the Gulf Coast and Salton Sea regions with experimental results suggests that alteration processes in sedimentary basins can, in large part, be attributed to water-rock interaction. -from Authors