Source and Origin of Subsurface Brine of the Kongquehe Sag Area in Western Lop Nur, China

The Kongquehe Sag, located in the western Lop Nur, has abundant pore subsurface brine. In order to study the source and origin, we tested and analyzed the hydrochemical composition and stable isotopes of the subsurface brine. The findings reveal that the brine exhibits a moderate to low degree of mineralization, with values ranging from 50.50 g/L to 91.14 g/L. The stable isotope compositions of unconfined and confined waters are different, with the mean values of δD being −8.00‰ and −51.75‰ and the mean values of δ18O being 10.08‰ and −6.01‰. These values are indicative of an intense evaporative environment prevalent in the Kongquehe Sag area. Furthermore, the 87Sr/86Sr ratios vary between 0.710642 and 0.710837, and δ34S values range from 9.2 to 10.7. These data suggest the long-term evolution of sulfur substances, predominantly through dissolution and sedimentation processes, with minimal influence from redox reactions. The data garnered from this research not only offer a novel perspective of the insights gained into the hydrochemical characteristics and the stable isotope signatures of the brines in the Kongquehe Sag area but also enriches the theoretical framework concerning the source and origin of subsurface brines, potentially informing future exploration strategies.