Characteristics Of Potash Sediment And Paleo Water Temperature In Bieletan,Qarhan Salt Lake,Qinghai Province

Qarhan Salt Lake,located in the east of Qaidam Basin,has a huge amount of salt mineral resources and is the largest potash production base in China.Qarhan Salt Lake is divided into four sections:beretAn,Dabson,Qarhan and Hobson.BeretAn section is located in the westernmost section of Qarhan Salt Lake.In the section,the liquid potassium salt resources are mainly extracted from the potassium rich and magnesium rich brine,but at the same time,there are about 180 million tons of low-grade solid potassium salt resources.Under the trend of decreasing brine resources and increasing mining costs,the low-grade solid potassium salt resources are gradually reduced Potash deposits have become the most potential mining objects in the future.In recent years,the relevant production enterprises have encountered some practical key problems in the liquefaction development process of low-grade solid potash ore in the beretAn section,mainly due to the rising of solvent water level and the extremely slow lateral flow and other reasons,resulting in poor ore dissolution effect.Therefore,studying the salt deposition characteristics of salt bearing strata in the beretAn section and the potash mineralogy and its genesis can solve the problem of low-grade solid potash The problems encountered in the production of potash mining provide geological theoretical basis.In this paper,the upper salt bearing stratum(Qh^S3)in the north of Bieletan section is taken as the research object.Through the mineralogy,inclusion temperature measurement and element geochemistry of the boreholes in the north,the following knowledge is obtained:according to the mineralogical study of the strata in the northern part of Bieletan section,the upper salt layer(Qh^S3)in this area is dominated by halite deposition,and the potassium salt minerals found in the strata are mainly halite,followed by carnallite,with less sylvite.The evaporite minerals in this area have been deposited in many stages,and the general trend is the continuous evaporation and concentration of Salt Lake Brine under the background of drought.The sedimentary sequence of salt minerals is gypsum?rock salt?halite?sylvite and carnallite.the element geochemical analysis test shows that in the salt bearing strata in the north of Bieletan,the peak horizon of potassium minerals is mainly in the 5.1-6.7m section;the maximum percentage content of potassium ions is 4.9%,which is higher than the boundary grade of solid potassium salt,and the average grade in the area is2.06%,which belongs to the category of low-grade solid potassium salt deposits.the temperature change curve of the ancient lake water in the upper salt layer(Qh^S3)is constructed through the temperature measurement research of rock salt fluid inclusions.The fluctuation range of the ancient water temperature is 15-20?,individual layers reach 28?,and the temperature peak layer is concentrated in the section of 6.5-7.3m,corresponding to the peak value of potassium salt deposition,reflecting the high water temperature,which also represents the high temperature,which is conducive to the rapid evaporation and concentration of salt lake brine.Compared with the temperature,the sedimentary layer with relatively high temperature has higher potassium content,which indicates that the water temperature of the ancient Saline Lake is high and the evaporation is strong,which is conducive to the potassium salt out.