Recent Hot Brine Dolomitization in the "Solar Lake," Gulf of Elat, Isotopici, Chemical, and Mineralogical Study

Abstract

The Solar Lake is a hypersaline monomictic, seasonally mesothermal pond on the Gulf of Elat coast. Bottom water temperatures reach 57°C, compared with about 20°C at the surface. Dolomite has formed recently in the sediment of the pond. The dolomite has a 6-7% mole excess of $$CaCO_{3}$$ and is poorly ordered. $$\delta^{18}O$$ of the dolomite averages $$+ 9.0\%_{0}$$ (PDB), its $$\delta^{13}C$$ has an average of $$+ 4.1\%_{0}$$. Coexisting aragonite is depleted by $$3-4\%_{0} in ^{18}O, its \delta^{13}C$$ is close to that of the dolomite. It is concluded that dolomite formed in the pond sediments by replacement of the existing aragonite, under conditions similar to those prevailing in the Solar Lake at present, i.e., temperatures close to 50°C and water isotopic composition of about $$+ 11\%_{0}$$ (SMOW). The dolomitization process is of the "Pekelmeer" type, where the driving mechanism is the reflux of hot brine, the Mg/Ca ratio of "which has been increased by gypsum precipitation.