The Geochemical Characteristics And Impact Factors Of Sulfur Isotope Of The Brine In Qarhan Salt Lake

Sulfur isotope is an important isotope geochemistry method.Since 1950s,some researchers had used it to research the formation and evolution of marine evaporite,and established changing curve of sulfur isotope.The sulfur isotope has been used generally to research evaporite basin and water,and it plays an important role in formation of ore deposit,metllogenic mechanism,formation and salted development direction of evaporite and ore prediction.Qarhan Salt Lake is not only the biggest sylvite and magnesium liquid deposit,but one of the important potassium production bases in our country.Scientists have researched detailedly on lithium,hydrogen and oxygen,boron and carbon isotopes,but little on sulfur isotope in brine.Therefore,on the base of current situation and previous research results,the paper uses the methods of element and isotope geochemistry to analyze hydrochemical characteristics and sulfur isotope compositions,to analyze hydrochemical changing in different sectors of river,to probe into the relevance between sulfur isotope and hydrochemical parameters,to analyze the impact factors on distribution of sulfur isotope,to clear the reasons of causing the difference,and to derive more information of metalogenic material sources and processes of Qarhan Salt Lake.The Qarhan Salt Lake includes two types of brine?magnesium sulfate sub-type and chloride-type?.The essential feature of brine in Qarhan Salt Lake is rich in Mg²⁺,K⁺,Ca²⁺,?HCO₃?^-,and lack of ?SO₄?^2-.There are differences in different sectors of river or different hydrochemical type water.Except for different primary deposit brines,the effects of human productive activity and supply of external water have played an important role.The values of sulfur isotope in Qarhan Salt Lake are between 6.66‰ and 12.14‰,and the average value is 9.07‰,which is relatively low and centralized distribution,and is different in different sectors.The value of sulfur isotope is negative correlated to ratio between calcium and chlorine,and is positive correlated to coefficient of desulfurization,which may caused by the precipitin reaction between Ca²⁺ and ?SO₄?^2-.The main influencing factors to sulfur isotope composition include: source of material,reducing action of sulfate reducing bacteria,fraction of evaporation and sediments,thermochemical sulphate reduction and openness or closure of system.The supply of river is the main factor which effects the sulfur isotope compositions in Qarhan Salt Lake.Partial original sulfate minerals dissolved by river go through the process of evaporation and sediment,and form the distribution characteristics of sulfur isotope in Qarhan Salt Lake.The values of sulfur isotope are positive correlated to content of sulfate ions.The difference of different sectors is mainly correlated to river water supply,sulfate minerals in sediments and the precipitation of some sulfate minerals.