| Yata gold deposit is located in the metallogenic area of Carlin-type gold deposit in southwest region,the southwestern Guizhou gold metallogenic area is ore concentration area of Carlin-type gold which belongs to Yunnan,Guizhou and Guangxi,and an important place that produces Au,Hg,Sb,As,Pb-Zn,Ag and a variety of dispersed elements.The geomorphic location of the Carlin-type gold deposit is located in the intersect position that was composed of southwestern margin of the Yangtze block and the Youjiang orogenic belt.The geologic and tectonic metamorphic evolution process of the two tectonic units determined the formation of the gold mineralization belt.Since the 1970 s,the earliest Carlin-type gold deposit(fine disseminated type)was found in southwestern Guizhou,and then more than 50 gold deposits(points)have been found in the area.So far,more than 500 tons gold resources reserves been verified.The geology,tectonics,geophysics,geochemistry and remote-sensing geological features reflect the area has potential to find large-scale gold resources.The predecessors studied geology,ore-controlling conditions,the geochemical characteristics of gold deposits,the form of gold,mineral processing test and the cause of deposit formation.Overall,the predecessor's studies about ore-forming fluids of the gold deposits are not perfect,and the ore-forming fluid is closely related to the genesis of the deposit.Therefore,this paper takes the fluid inclusions of the Yata gold deposit as the research object.Through the test data,the calculation and analysis for the inclusions to further determine the metallogenic hydrothermal type of Yata gold deposits and its genesis.This paper is based on the field geological survey of the Yata gold deposit to further understand the metallogenic geological background and geological characteristics of the deposit.From the microstructure,observing and studying inclusions of the samples under the microscope,and measuring their temperature by homogenization method to obtain the uniform temperature and the freezing point temperature of the fluid in the inclusions,through the calculation to obtain the fluid salinity,density,pressure and other related parameters.Combined with previous research data on the deposit,discussing the ore forming fluid properties,fluid sources,fluid migration and gold precipitation of Yata gold deposit in order to judge its genetic typesThe paper mainly draws the following points: there are three types of inclusions in Yata gold deposit,among them,the gas-liquid two phase inclusions are the most,followed by pure liquid inclusions,three-phase inclusions at least.The shape of the inclusions is irregular,sub-elliptic,elliptic and negative crystal,the size of inclusions is generally 3~20?m,pure liquid inclusions are mostly small inclusions,so they are mostly difficult to observe.The paper mainly selects the gas-liquid two phase inclusions to test the data,getting the inclusions' uniform temperature(101.7~293.3?),salinity(0.35~13.61wt%),density(0.75~1.06g/cm~3),mineralization pressure(26.5~73.2MPa),mineralization depth(less than 3km)and other information.It is concluded that the ore-forming fluid medium is mainly derived from sedimentary formation water,oilfield water or atmospheric precipitation,the deposit has the characteristics of epithermal medium deposits fluid.Therefore,this paper argues that the type of Yata ore deposit is epithermal medium deposit. |
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