Study On Geochemical Characteristics And Genesis Of Potassium-rich Brine In Mahai Salt Lake In Qinghai Province

Potash has been a shortage of important strategic resource in China.Mahai Salt Lake in Qinghai Province is a modern medium-sized potsash deposit that is a solid-liquid coexistence mine. A large number of potash resources distributes in pressure brine layer and associated solid salts seam, Potassium-rich brine in the area is mainly in form of chemical intercrystalline pressurized groundwater(WⅡ~WⅤ). With the development of the deep pressurized brine in Mahai Salt Lake, a number of urgent problems about hydrogeology are to be solved, so the study on geochemical haracteristics and genesis of potassium-rich brine is of great significance for sustainable exploitation of it.In this paper, geochemical haracteristics and genesis of potassium-rich in the salt lake are sunmmarized by hydrogeochemical method and its genesis is investigated,drawing the following conclusion mainly:the main chemical composition of intercrystalline pressurized brine are K+, Na+, Ca2+, Mg2+, Cl- and SO42-, minor components are mainly Li+、Br-、I-、Sr2+、Rb2+、B2O3 and so on. Most salinities of brine are about 320g/L, and hydrochemical types is mainly magnesium sulfate subtype. They reveal that Mahai potassium mine has evolved to late.of salt lake. The plane distribution of chemical composition of intercrystalline pressurized brine is that salinity showes an increasing trend from the southwest to the northeast. The content of KCl and salinity show a strong consistency, that indicates KCl is enriched with concentrating and evaporating of brine.The points about hydrogen and oxygen isotopes of intercrystalline brine are all near the global atmospheric precipitation lines, reflecting the potassium-rich brine is originated in local precipitation. Closed space formed by tectonic movements provides the most basic of environmental conditions for brine mineralization. The correspondence of salification in salt lake and the ancient climate shows that extreme arid climate provides the necessary conditions for the brine concentrated mineralization and salts enriching. Intercrystalline pressurized brine is mainly from continental dissolved water, because of the influence by tectonic, sedimentary water supply is in local area. The brine is a mixture of dissolved waret and sedimentary water.