Geologists say that during the Himalayan orogeny, a large area of land subsidence occurred in the northern part of Zhongtiao Mountain. This subsidence extended to Emei Mountain in the north and Chaoyi in Shaanxi Province in the west, forming the primitive prototype of Yuncheng Basin and Yanchi.
Two or three million years ago, at the beginning of the Cenozoic Quaternary, the crust changed again, and Zhongtiaoshan moved vertically, causing a fracture at the northern foot of Zhongtiaoshan, and a long and narrow depression belt appeared, gradually forming a pool, which was finally turned into a salt pond by the continuous deposition of salt.
Salt minerals are mainly formed in sediments from the Middle Pleistocene to Holocene 10,000 years ago. The salt-bearing system is about 300 meters thick, and the other is the salt in brine. Yuncheng Yanchi is a closed-flow artesian basin, and the surrounding groundwater converges to the center of the basin. In the process of confluence, due to the dissolution of salt in different strata and the constant change of water quality, the salt content of diving water entering the salt pond is as high as 3 ~ 5g/L, and the roof and floor of the seam are generally clay, which has no dissolution and good sealing performance.
Composition of Yuncheng Salt Lake
According to the spatial distribution analysis of sediments and salt deposits, since the formation of salt ponds, the sedimentary center has been moving from northeast to southwest, with a maximum distance of 20 kilometers. During this period, two drastic structural changes occurred, which caused the discontinuity of sedimentation and the fault cutting of ore bodies.
The early sedimentary feature is sulfate reservoir, and the later is sulfate-chloride reservoir. The main salt-forming substances are sodium sulfate, magnesium sulfate and sodium chloride. Minerals are mirabilite, glauberite, glauberite, salt, gypsum and magnesium borate, and a small amount of associated elements are salt-forming elements such as Australia, iodine, pit, nickel, Dan, Jia, calcium, potassium and Jia, which migrate to the low-lying areas of the basin with water, evaporate and concentrate along the way, and finally form Yuncheng Salt Pond.
Reference to the above content: Baidu Encyclopedia-Yuncheng Yanchi