Deep Fluids in Sedimentary Basins
This chapter reviews what is known about the geochemistry of water in sedimentary basins in the continental and transitional continental oceanic crust. The emphasis is on water below the zone of shallow meteoric groundwater circulation and on the main processes that are responsible for the modification of the chemical and isotopic composition of these waters including (1) mixing; (2) dissolution of evaporites, especially halite; (3) reflux and incorporation of bitterns, the residual water remaining after the precipitation of evaporites; (4) dissolution and precipitation of minerals other than evaporites; (5) interaction with rocks, principally clays, siltstone, and shale that behave as geologic membranes; (6) activity of bacteria that can survive in sedimentary rocks at temperatures up to 80 degC; (7) interactions with organics, including petroleum and solid organic matter; and (8) diffusion, especially in and near salt domes.