The accumulation of potash in a continental basin: the example of the Qarhan Saline Lake, Qaidam Basin, West China

The Qarhan Saline Lake is now in the stage iplaya lakei, where brine lakes and a dry salt plain coexist. Although an inland lake, it has large amount of marine-type salts. In this take, there are three different occurrences o f potash salts: disseminated, stratoid and layered. Through the investigati on of the sediments, hydrological cycles, geochemical processes and geomorp hology in and around the lake, and using the specific interaction solubilit y model, the formation mechanisms of potash salts have been studied and des cribed in this article. It was found that disseminated potash salts precipi tate through the slow evaporation of intercrystalline brine. Cooling is an additional factor in the precipitation of the disseminated potash salts. Hy drological cycles are responsible for the accumulation of potassium in brin e takes (e.g., the Dabuxun Lake) seated in the dry salt plain and the forma tion of stratoid potash along the lake shore. During the playa-lake stage, the shift of inflow river channels may result in the dissolution of dry sal t plains and the formation of a brine lake, The sediments, including dissem inated potash salts, are redistributed after the dissolution. This is a ver y important process for the accumulation of potash deposits as discovered i n the Dadong Ancient Lake.