Geological And Geochemical Characteristics Of Polyhalite In Eastern Sichuan

China is a country with a shortage of potassium resources.It has long relied on imports to meet the needs of agricultural production.With the development of industry and the study of potassium-rich brine potassium resources,it has been found that polyhalite is not only abundant in storage,but also widely used in utilization.The economic value of solid potassium resources,and the study of polyhalite on the depositional evolution of the potassium-salt period in the Sichuan Basin,the interrelationship between different types of potassium salts,and the metallogenic model of China's marine-type potassium salts There is a very important scientific research significance,so this research has been carried out.Previous studies on polyhalite have been studied quite well,but the geochemical characteristics of polyhalite and the relationship between polyhalite and potassium-rich brine are The research is relatively rare,so in order to study the geochemical characteristics of the polyhalite layer,and to rationalize the relationship between the polyhalite and the potassium-rich brine,this paper based on the regional background data of the predecessors,through Xuanhan in Chuandong Field field surveys conducted in the region,stratified sampling analysis of boreholes in potash-rich brines,combined with other borehole data from the region,on polyhalite Geochemical characteristics and genetic model to explore the relationship polyhalite and potassium-rich brine is the main direction,achieved the following key findings:1.After collecting the basic geological research of the predecessors,based on the measured section of the Xuanhan area in the eastern part of the country,combined with the borehole profile of the potash borehole in the area,the comprehensive analysis concluded that the Xuanhan area in eastern Sichuan The polyhalite stratum is developed in the Triassic Jialingjiang Formation?T₁j?and the Leikoupo Formation?T₂l?.The main polyhalite layer is divided into two parts:T₁j₂⁴,T₁j₂⁵-T₂l₁¹,of which T₂l₁¹ is used.The most important polyhalite layer has the highest content,reaching more than 90%.The polyhalite and stone salt are interbedded with anhydrite.The Triassic in the Xuanhan area developed three major salts,followed by carbonate rocks,evaporites,mung bean rocks?volcanic tuffs?,and three main types of sedimentary facies:the evaporation platform phase-limited platform phase-open platform phase.Is a carbonate platform deposition system2.Through the analysis of the trace and isotopic elements of the polyhalite layer,it is considered that the potassium and sodium values of the macroelement are abnormally increased.The regular micro-element of the polyhalite layer is in a lower-value area.And the variation of each constant component has no particularly obvious regularity.The content of the trace elements in the shallow to deep is accompanied by the fluctuation of the content of the polyhalite,and the correlation is good.The light rare earth elements are relatively enriched,and the heavy rare earth elements are relatively depleted.Both Eu and Ce of the polyhalite layer have positive anomalies.The results of isotope analysis show that the depositional environment of the polyhalite layer is a stable sea level depression and oxidized environment with plate uplift.3.Comprehensive analysis of Triassic polyhalite in the eastern Sichuan area has the second most salt-forming period and wide salt formation,and the distribution of polyhalite is extensive.The complex formation conditions are related to many factors.The ancient geography needs to be closed or half.The closed and limited platform and evaporation platform environment,as well as the paleo-climate of the strong drought evaporation type and the ancient structure and basin system of the depression type or marginal depression of the platform type,the origin of the polyhalite is native and similar.There are both births and births,and the same students can refer to gypsum and anhydrite or other salt minerals.They may also have mixed doping of different water bodies,but the whole cause is mainly primary sedimentation;The possibility of a brine,while there is a close relationship between the polyhalite and the potassium-rich brine.4.The relationship between polyhalite and potassium-rich brine is that the natively deposited polyhalite acts through water rock,precipitates K ions into the brine,increases the content of K in the brine,forms a potassium-rich brine,and simultaneously forms a potassium-rich brine and hard The metamorphism of gypsum forms a quasi-alternative polyhalite,which is a mutual influence,and the causes of the two are closely related.