Major-ion geochemistry and mineralogy of the Salt Lake (Tuz Gِlü) basin, Turkey

In the Salt Lake basin of Turkey, chemical composition of inflow surface waters defines a continuous trend from CaHCO3-rich spring waters to NaSO4Cl-rich brines. Considerable compositional variation exists among the surface waters. Water-rock interaction governs compositional variations in springs, streams and rivers, and is enhanced by evaporation and precipitation of calcite and protodolomite. Solute concentrations of the streams and the rivers are partially controlled by the mineralogy of the playa deposits. The concentration increase from inflow surface waters to a NaCl-type lake surface brine is not accessible to direct observation. The principal cause of the evolution from SO4- rich brine to CI-rich brine in the lake is interpreted as the recycling of solutes through the differential dissolution of efflorescent crusts. lake, major-ion concentrations generally exhibit an evaporation-dependent evolution trend that is further modified by precipitating halite, gypsum, aragonite and calcite. Sediments of the lake are predominantly composed of gypsum, dolomite, huntite, magnesite, and subordinately of polyhalite minerals. Magnesite and huntite are mostly early diagenetic minerals that have been formed by the transformation of dolomite in the presence of pore fluids with a high MgCa ratio.