Study On The Metallogenesis Of Hongshiliang Gold Deposit In Hami Area,East Tianshan

The East Tianshan metallogenic belt is an important metallogenic belt in the west of China.It is located between the Junggar Basin and the Tarim Basin.It belongs to the southern edge of the Central Asian orogenic belt and is an important part of it.The Hongshiliang gold deposit is a newly discovered gold deposit in the Hami area of the East Tianshan Mountains in recent years.It is located at the southern edge of the Dananhu Island arc belt and the northern end of the Kanggur-Huangshan collision zone.The ore body of the Hongshiliang gold deposit mainly locats in the calcium-alkali volcanic rocks of the Tousuquan Formation in the Middle Devonian.This study relies on the regional geological survey of the"Geological Survey of Mineral Resources in Jingxia Region of the East Tianshan Metallogenic Belt"in the Sanchakou Range and Wutongwoziquan Range in the Hami Region of the East Tianshan Mountain,combined with previous studies on gold deposits in the same area.The Hongshiliang gold deposit is the research object.Through the research of petrology,mineralogy,chronology,rock geochemistry,fluid inclusions,hydrogen and oxygen isotopes,and lead isotopes,the Volcanic rocks and Carboniferous intrusion of the Tousuquan Formation were analyzed.The rock series,formation age,rock genesis and tectonic setting of the rock discuss the ore-forming fluid properties,source of ore-forming materials,metallogenic mechanism and deposit genesis of the Hongshiliang gold deposit,determine the type of deposit,and summarize the metallogenic model.The following results were achieved:The Hongshiliang gold deposit is located at the southern edge of the Dananhu Island arc belt in the Hami area of the East Tianshan Mountains and adjacent to the northern end of the Kanggur-Huangshan collision zone.The ore deposits are strictly controlled by faults and locat in the NEE-oriented secondary faults in the Kanguertage fault zone.The ore-bearing surrounding rocks of the Hongshiliang Gold Deposit are volcanic rocks such as Andesite,Ying'anite and Ying'an or andesite volcanic breccia in the Middle Devonian Tousuquan Formation.The Tousuquan volcanic rocks belong to the calcareous-alkaline volcanic rocks series.Combining the rock geochemical characteristics and the rock assemblage tectonic environment,the Tousuquan volcanic rocks are formed in the island arc tectonic environment(Danahu Lake arc)on the continental margin.The Carboniferous magmatic rocks controlled by the same structure as the Hongshiliang gold deposit belong to the calc-alkaline rock series and have the characteristics of homologous evolution.The tectonic background is the island arc environment.The gold-bearing geological bodies of the Hongshiliang gold deposit are mainly quartz veins and rhyolite porphyry-prefine rocks,which delineate two gold mineralization zones in total.The first gold mineralized gold average grade is 0.95×10^-6,and the second gold mineralized gold average grade is 0.2×10^-6.The ore minerals are mainly pyrite,natural gold,limonite,and a small amount of magnetite.The gangue minerals are mainly quartz,chalcedony quartz,and chalcedony,and the secondary are alumite,chlorite,montmorillonite,Sericite,potash feldspar,etc.The ore types are mainly breccia ore and reticulate ore.Wall rock alteration has a certain zoning,and its alteration includes silicification,pyrite mineralization,sericite,pyrite sericite,epidote/chlorite,carbonate and ice feldspar.Petrographic observation of quartz fluid inclusions in Hongshiliang ore body is divided into pure liquid inclusions,liquid-rich gas-liquid two-phase inclusions and gas-rich gas-liquid two-phase inclusions.The measurement of uniform temperature and salinity of fluid inclusions shows that the ore-forming fluid has the characteristics of low temperature(131?276?),low salinity(2.41?9.60%Na Cleqv),low density(0.848?0.966g/cm³),Has the characteristics of typical shallow low temperature hydrothermal deposits.Hydrogen and oxygen isotopes and laser Raman composition analysis show that the ore-forming fluid is a mixture of magmatic water and atmospheric water.During the evolution of the fluid,atmospheric water is continuously added to form a near-neutral fluid.The results of lead isotope tests indicate that the source of ore-forming materials is complex and originates from the product of magmatic activity of crust-mantle mixing.The ore-forming fluids of the Hongshiliang gold deposit are mainly liquid-rich gas-liquid two-phase inclusions.Cryolite and chalcedony appearing in veins or around the mineral ring are observed under a microscope,and the liquid-rich gas-liquid two-phase inclusions The coexistence of gas-rich gas-liquid two-phase inclusions indicates that the ore-forming fluid boils during the ore-forming stage.Boiling is the main metallogenic mechanism that causes the metallogenic materials of Hongshiliang gold deposit to unload and aggregate into ore.U-Pb isotope chronological test research shows that the zircon dating result of the Tousuquan Formation volcanic rocks in the ore-bearing surrounding rock head is 383.7±4.3Ma;The zircon U-Pb dating of diorite in the mining area is 332.1±2.7Ma.Combining the structural background of Hongshiliang gold deposit,ore-bearing surrounding rock,ore-controlling structure,wall rock alteration,ore body characteristics,ore mineral characteristics and ore-forming fluid characteristics with the typical low-sulfurized shallow-to-low temperature hydrothermal gold at home and abroad According to the comparison of the ore deposits,it is determined to be a low-sulfur shallow-to-low temperature hydrothermal gold deposit.The geological process of diagenesis and mineralization experienced volcanic activity under the crust-mantle mixing of the subduction of the ancient Tianshan oceanic plate in the Middle-Late Devonian to the Early Carboniferous to form ore-bearing fluid.Boiling action causes Au and other metallogenic materials to accumulate and precipitate,eventually forming a low-sulfurized shallow Low temperature hydrothermal gold deposit-Hongshiliang Gold Deposit.