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The Highest Degree of Mineralization-Chaerhan Salt Lake
Lying in the subsidence center of Cenozoic in the Qaidam Basin and extending across Golmud and Dulan county of Qinghai Province, Chaerhan Salt Lake is the largest salt lake in China, with liquid and solid facies coexisting. It is composed of Seshe Lake, Dabuyun Lake, North Huobusun Lake, South Huobusun Lake, Large Biele Lake, Small Biele Lake, Daxi Lake, Cooperation Lake, Unity Lake and Dongling Lake, which are perennial and seasonal , and stretches of sabkha . The flat elevation is 2678-2683m, 168km long, 20-40 km wide, covering an area of 4708.8 km2. Among them, covering an area of 0-31.92 km2, the Cooperation Lake is 0-0.03m deep. Its density is 1.361 in flood period, and the mineralization degree is 527.15g/L.
About 37000 years ago, the lake was still a freshwater lake or slight saltwater lake. However, in the later long time, the wet and dry climates alternated in the lake region, so did the salt concentration and desalinization of the lake, roughly 5 times respectively. Nearly 15000 years ago, the lake developed into its prosperous period, and deposited the 4th salt sediment spreading all over the lake region. About 5000 years ago, part of the lake region deposited the 5th salt sediment. Thereafter, because the lake region was becoming more arid, the lake range shrunk thereupon. Except some brines reserved near the lake mouth, most of the lake region developed into sabkha. Therefore, the salt lake where sabkha and brine lakes coexist came into being. At present, because the lake water supply is unable to make ends meet, the water surface is still continuously shrinking back and the area of sabkha is expanding.
The lake region belongs to the arid or extremely arid climate of Qaidam Basin. The average precipitation is only 24.7mm in the whole year, while the annual evaporation is up to 3543.1mm. The lake water mainly relies on surface runoff for replenishment. There are 18 major rivers entering the lake among which the Golmud River is the largest (447km long). The lake region is a mineral deposit with the liquid and solid facies coexisting, which is of highly synthesized utilities value. The liquid mineral deposit is mainly composed of potassium , and it is the largest potassium and magnesium liquid mineral deposit already verified, and has started to be exploited now.
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