Study On The Occurrence And Geological Features Of Mingsai Gold Deposit In Zhaxikang Mine Area Of Tibet

Mingsai gold deposit,located in the area adjacent to the mining area and zhaxikang super-large lead-zinc-antimony-silver polymetallic deposit known to South Tibet,have been found in Zhaxikang Lead-zinc-antimony-silver Polymetallic deposite in recent years.The study of this gold deposit has expanded the thought of searching for gold deposits in this mine,and provides some referential value for the mineralization of gold ore deposit in the tethyan-himalaya gold deposits.The geological features and the study of the occurrence of gold in Minsai gold deposit show that the mining area is mainly exposed to the middle-upper Jurassic Lu Re formation and the upper Jurassic Wei Mei formation and the sangxiu formation.Ore body growing in the lower Jurassic strata.The layer characterized by monoclinal stratum and it tends to be close to EW,which tends to be N,and the inclination is 10~15.Formation lithology is a set of sandstone and calc slate,which includes alteration tuff concordant intruding into the stratum.The alteration tuff mainly manifested as silicification,pyritization,arsenopyrite mineralization,sericitization and carbonatization alteration.The silicification is characterized by the development of the veins in tuff and the veins of the veins.Pyrite and toxic sand are disseminated and they are closely related to gold mineralization.Scanning electron microscopy SEM and energy spectrum analysis EDS and characteristic X-ray scan results analysis show that the gold in the ore body is the "visible gold" that can be recognized by the scanning electron microscopy.The gold exists in the form of Independent mineral granules,the lattice gold is not found.The gold show three characteristics: embedded gold,intergranular gold,crack of gold.Except the partial distribution in silicate minerals and clay minerals(21.21%),gold mainly occurs in pyrite and arsenopyrite(79.79%).Arsenopyrite is characterized by the form-half the form structure and needle,diamond,plate shape,Which lives with pyrite.The gold deposits are long,plate-shaped and irregular,often distributed between pyrite and Arsenopyrite grains.The composition of gold is mainly based on natural gold,and the palladium gold deposit,silver natural gold,mercury natural gold and nickel natural gold can also be abserved.The size of the gold Mineral grains is(0.001~0.03mm),the most portion is extra micro extreme-minute particle gold(0.005~0.0002mm),average grain diameter is 0.0023 mm,66.67%.The second is micro minute particle gold(0.01 ~ 0.005mm),average grain diameter is 0.0066 mm,24.24%;micro medium particle gold(0.05 ~ 0.02mm),average grain diameter is 0.025 mm,6.06%;micro fine particle gold(0.02 ~ 0.01mm),average grain diameter is 0.012 mm,3.03%.Compared with typical orogenic type,carlin type and Epithermal gold deposit,The geologic feature of Mingsai gold deposite is similar to characteristic feature of Epithermal gold deposit and it distinguish from the typical orogenic gold deposite and Carlin type deposit.Mingsai gold deposit may belongs to Epithermal gold deposit.