Research On The Geochemistry And Thermodynamics Characteristics In Xianghualing Mining Area In Hunan Province

Taking the mineralize serial theory as guidance,through the materials collection of Xianghualing Sn-polymetallic mining areas and the comprehensive analysis of the former research results,the thesis make the exploratory research on the basis of the outdoor geological survey.The main analytic methods includes the comprehensive approach,mineralogical approach,petrological approach,geochemical approach,geological thermodynamics and fluid inclusion approach aiming at the ore-forming physicochemical conditions,the ore-forming materials source,the rock-forming mechanism,the metallogenic mechanism,the ore deposit genesis and metallogenic model.The main achievements are made as follows:â‘ According to petrological and petrochemical characteristics of magmatic rocks,microelements and REE geochemiscal characteristics of Xianghualing mining area,we draw the conclusion that the rock-forming elements of granite K/Na+K and Al₂O₃/K₂O+Na₂O+CaO's index value are 0.39—0.45 and 0.54—0.69 respectively,ACF is "S" type area,it is 0.7824 that the constituent of initial strontium isotope,and the age of Nd mode is the negative value, demonstrated that the granite in this area are the products of crust-mantle mixing. The rock bodies have the characteristics of high silicon,rich alkali,containing calcium magnesium iron,rich in tungsten Sn mineralize element and volatilize components of lithium and Fluorine etc.â‘¡Determine the microelements to the rock of the main type of mining area and metal minerals in Xianghualing mining areas,getting the characteristics that the sulphides related to Sn mine all have rich arsenic,tungsten,Sn and poor sulphur.â‘¢Through the research on the physicochemical conditions of the formation of the skams for the first time,the results show that the rock-forming temperature is 430℃—570℃,the pressure of rock-forming is 1000×105Pa, XCO₂ is 0.22-0.02.Because of the drop of the fluid temperature and the participation and flow of H₂O,the rock-forming temperature and the XCO₂ of the later skarns fluid drops.When the temperature is 570℃,the logfo₂ varies from-24.8 to -20.2.When temperature is 430℃,the logfo₂ varies from -26.0 to -16.2.â‘£On measuring the temperature and salinity of inclusions in greisen-cassiterite-sulfides,cassiterite-quartz-sulfides,sulfides and fluorite-carbonate metallogenetic stages for the first time,the main results show that the data of mineralization temperature and salinity are respectively 300℃—350℃and 3.85—6.9wt%NaCl in greisen-cassiterite-sulfide, cassiterite-quartz-sulfide stage;200℃—270℃and 0.53—6.4wt%NaCl in sulfide stage;85℃—178℃and 0.2—4.5 wt%NaCl in fluorite-carbonate stage.⑤The thesis gain the results of oxygen fugacity,sulfur fugacity,pH in every stages via thermodynamic calculation for the first time,and estimate the transfer model and capability of Sn,Cu,Pb,Zn.â‘¥It can draw the conclusion thatδ³⁴S_ΣS in solution has an approximate content(0±3‰)with S isotope of pyrrhoSne by measuring S and Pb isotope of sulfide in ore bodies,a lower value shows S in hydrothermal fluid is origin from magma;Linear array of Pb isotope in galenite suggests that Pb may be multisources.⑦According to geological characteristics of mineral area,geological conditions of mineralization,geochemical characteristics,material sources of mineralization,mineralization patterns,as well as physical and chemical conditions of mineralization,it summarize the mineralization pattern and genesis of ore deposit of Xianghualing mining areas,considering that mineralization materials in this deposit mainly come from magma,genesis patterns of deposit include high-temperature gas-liquid Nb,Ta deposit related to albitization laying in or on the edge of granite rock bodies,median-high temperature Skarn Sn,Be deposit related to skarnized laying at the inner contact-belt of granite and carbonate rock bodies;median-high temperature cassiterite -sulphide mineral deposit related to skamized laying at outer contact-belt of granite and carbonate rock bodies and median-low temperature hydrothermal liquid Pb-Zn-Ag deposit related to silicification,fluorite, propylitization laying in wall rocks;Series of generalized magma- hydrothermal liquid type Sn-polymatellitic related to magmatic activity in Yanshan period as a whole.