Saline and dilute groundwaters of distinct origin converge and mix in two juxtaposed Paleozoic aquifers in Missouri and Kansas. Research is proposed that will investigate the processes that control the flow history and geochemical evolution of groundwaters in this large-scale flow system. Processes to be examined include gravity-driven flow, fluid mixing and water-rock interaction. This examination will be accomplished through the analysis of the waters for a range of chemical and isotopic systems, including major and trace element concentrations, H, O, Sr, Nd, B, U, Th, Pb and Ra isotope compositions, and rare earth element concentrations. Models for the evolution of the groundwaters will be evaluated using quantitative models that simulate chemical and isotopic exchange during the migration of subsurface fluids. The models developed for this flow system are expected to have significant implications for a variety of geologic and environmental issues, such as the origin of basinal brines and Pb-Zn ore deposits, the transport of radionuclides, trace metals and hydrocarbons in the Earth's crust, the diagenesis of sediments and the management of water resources.
