| The Lead and zinc resources are rich in the southern Tianshan area,and typical lead-zinc deposits are Uragan lead-zinc deposit,Hoshbulak lead-zinc deposit and Shalitashi lead-zinc deposit,Qiong Aber lead-zinc deposit and Kanling lead-zinc deposit.The tectonic position of these lead-zinc deposits is located in the northern margin of the Tarim and the southern Tianshan sedimentary basins,belonging to the passive continental margin.The controversies about these areasare mainly in the ore classification,mineralization age and mineralization process,metallogenic model of the deposits.In this study,we focus on above issues,the main results and understanding as follows:Based on the Rb-Sr and Sm-Nd isochron ages of co-sulfide and carbonate minerals in five lead-zinc deposits,the isochron age is 55.4 ± 2.2 Ma(Uragen),55 ± 2Ma(Hoshbulak),258.2 ± 2.8Ma(Shalitash),256.1 ± 7.1 Ma(Kanling),260.8 ± 7.3 Ma(Qiong Abe).It is found that the age of mineralization is mainly concentrated at about 260 Ma and about 55 Ma,that is,early Paleozoic Permian and early Cenozoic.It is believed that these two periods are two major periods of the formation of lead-zinc deposits in the southernwestern Tianshan area.Combined with regional tectonic evolution,the former corresponds to the Late Paleozoic South Tianshan Ocean closed orogenic stage,since the latter corresponds to the Mesozoic and Cenozoic India-Asia collision event.The tectonic compressive movement in southwesternTianshan region is the main driving force for the regional lead and zinc mineralization.The contribution of regional tectonic extrusion to metallogenesis is mainly composed of three aspects.Firstly,the tectonic movement caused large-scale fault fracture and formed a channel for fluid flow and migration,followed by tectonic movement formed a largescale fold,syncline anticline and broken zone,forming a large area of ore capacity.The lead-zinc deposits in the area are all in the syncline anticline anticline.The fault fracture zone forms a good ore-holding space on the second-level scale,for example,the Hoshbulak and Kanling deposits.The existence of syncline and anticline well preserved the ore bodies,such as the Uragan deposit.Secondly,the tectonic movement promoted the fluid migration and convergence,which is the main driving force of the fluid.Finally,the relaxation phase after the tectonic extrusion also promoted the formation of lead-zinc deposits.The tectonic backgroundof the regional lead-zinc deposits is thepassive continental margins,and the mining area is mainly controlled by faults and crushing zones.Most of host rock are carbonate rock or carbonate-clastic assemblage.The main source of metal is crust source,The Sulfur reduction mechanism is mainly thermochemical reduction mechanism and biological reduction mechanism.Some of the deposits have organic matter involved in the reduction process.The fluid is low temperature,with the nature of the basin brine.Based on the geologic characteristics of the geotectonic background and mine area and the geochemical characteristics of the predecessors and this study,it is considered that the lead-zinc deposits involve in this study in the southern Tianshan area,the Uragan lead-zinc deposit,Hoshbulak lead-zinc deposit,Shalitashi lead-zinc deposit,Qiong Aber lead-zinc deposit and Kanling lead-zinc deposit can be classified as MVT and its subclass. |
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