Reseach On Geology,and Geochemistry Of The Aqishan Deposit,Eestern Tien Shan

The discovery of Aqishan lead-zinc deposit in recent years by means of geochemical exploration.Located in the Qoltag orogenic belt in the East Tianshan Mountains.And the location of Qoltag orogenic belt is located in the northern part of the eastern Tianshan Mountains.A large number of Carboniferous volcanic rocks developed within the belt.Its distribution is mainly controlled by the Kanguertage fault and Aqqikkuduk faults.The area of??the mining area is approximately 6.75km~2,and the lead and zinc reserves total up to 1.97million tons(lead:370,000 tons;zinc:1.6 million tons).The average taste of zinc is 0.85%,and the average taste of lead is 0.2%.The strata of the mining area is the fourth lithological section of the Yamansu Formation(334.2±2.5 Ma),showing NE-SW strike,SE trend,and inclination angles of 40°?55°.The ore bodies are distributed along the bedding in the surrounding rock strata and controlled by the strata lithology.Through the study of mineralogy,it's found that the ore hosting lithology is mainly tuff and skarn,and it's more enriched in skarn.Among tuffs,basaltic tuffs and dacite tuffs are relatively poor,andesite tuffs,crystal tuff are higher.The main body of the rock mining area presents the characteristics of whole-rock mineralization.In skarn,the Magnesium iron garnet skarn is more broken but more rich,and the calcium-aluminum garnet skarn is relatively intact but more poor.The exposed rock mass in the mining area is granite porphyry,but there is no obvious contact with the ore body.According to the microscopic mineralogical study,the ore-forming process is divided into two metallogenic stages:the skarn mineralization stage and the hydrothermal mineralization stage.And a large number of garnets and other minerals,and these garnet provide a good channel for hydrothermal filling and percolation.And many other minerals,such as pyrite,sphalerite,galena,etc,formed by hydrothermal mineralization stage.According to the S isotope data,the S source of metal minerals is Closely linked to skarn or tuff,and S of metal minerals may be provided by strata.The description of Pb isotope mainly comes from the mantle lead,which is influenced by the orogenic effect and may be contaminated by lead from the upper earth's crust.The environment of metal mineral formation,surrounding rocks and skarn in the mining area,is a mixed environment composed of earth's crust and mantle subduction zones.It is magmatic mineralization under the action(maybe under the influence)of magmatism.Pyrite Re-Os dating data show that the pyrite metallogenic age is 301±13 Ma(MSWD=10.3),which shows that the ore-forming age around the late Carboniferous.In conclusion,according to the mineral ore body spreading along the stratum,skarnization is generally developed.It can be inferred that the tuff is firstly metasometism with the tuff to form skarn.In the later stage,the hydrothermal fluid is controlled by the horizon and is filled and percolated along the horizon and fissures.Filtration generation and mineralization,thus forming a horizon-controlled skarn deposit.