Study On Geological Characteristics And Genesis Of Basihu Polymetalic Deposit,Tuotuohe Area,Qinhai Province

Basihu area lie in the northern section of the West extension of the Sanjiang metallogenic belt.The Sanjiang metallogenic belt is an important metallogenic belt in China,There has be found multiple large and super large deposit with the eastern section.In recent years,many kinds of ore deposits and mineralization clues has been found,Tallogenic geological setting has the conditions of the large and super large metallogenic type.Regional metallogenic condition is very advantageousMine strata dominated Permian,The emergence stratum mainly is Kaixinling Group Which include Nuoribagaribao Group and Jiushidaoban Group.Other strata are alluvial deposits of late Pleistocene,Holocene alluvial deposits and lacustrine deposits Which is sporadic distribution.The fault structures are relatively developed.The faults can be divided in three group,respectively to NW?nearly NS?NE.NW fault structure is closely related to mineralization,It is the main ore controlling structure in the area.Regional Magmatic rocks activity is relatively frequent and distributed in central and southwestern in Basihu area mainly late Haixi-early Yinzhi period magmatic.The lithology is diorite and diabase.Basihu mining area delineated total 5 mineralization alteration zone,and 9 Pb-Zn ore body.The M9 is The main ore body.The ore bodies are strictly controlled by the double control of steep dip tensile fracture and limestone formation.Mineralization is drastically reduced or disappeared when across limestone formation.Ore types are mainly sulfide ores.The main metal mineral galena,sphalerite,chalcopyrite,pyrite and limonite,elemental minerals are very small amounts of silver.The ore structure mainly based on with allotriomorphic granular texture,hypidiomorphic texture,semi self euhedral granular structure and cementing structure,also visible contains structure.The ore structure is dominated by massive structure?disseminated structure and fine vein structure.Wall rock alteration includes silicification,carbonation,kaolin,chloritization,sericitization,baritization etc.Which carbonatization and silicification and mineralization are closely related.The fluid inclusion research of Basihu polymetallic deposit shows that the main metallogenic temperature range is 140?~210?,salinity range is 4~11wt%NaCl,fluid density is 0.93~0.98g/cm~3,depth is between 1.25~2.3km.Mineralization temperature of the deposit belongs to the medium low temperature mineralization,and the ore forming fluid belongs to the category of medium and low salinity.The depth of mineralization belongs to the middle and shallow.The mineralization of polymetallic deposit in Basihu is relatively complex.The characteristics of multiple stages of mineralization.It grew fine stockwork lead-zinc ore,placer type lead ore and medium low temperature hydrothermal vein type lead-zinc mine.It's the different types of Pb Zn deposits formed in different tectonic settings and in different times in this erae.