Geochemical Processes in a Modern Coastal Groundwater Mixing Zone and TheirHydrologic and Petrologic Implications

摘要

Mixing of seawater and freshwater in a coastal carbonate aquifer system hasproduced a chemically reactive environment for diagenetic processes. Mineral dissolution, alteration, and precipitation are common processes occurring in the groundwater mixing zone. The dynamic flow characteristics of hydrologic systems are dependent upon the effects of diagenesis on porosity and permeability. The authors current understanding of the hydrogeologic and petrologic implications of geochemical processes in this environment is incomplete. The study tests the general hypothesis that carbonate diagenesis in the groundwater mixing zone of a coast is a dynamic and critical process in the development of porosity and permeability. The specific objectives are to (1) establish the geochemistry and petrology of a modern mixing zone, (2) quantify the geochemical reactions that yield the current composition of the mixing zone, and (3) relate these geochemical processes to the petrologic and hydrogeologic evolution of a coastal limestone aquifer.