| Based on the existing basic geological survey and mineral exploration data in Yunnan Provice and other scientific researchs on the area, the metallogenic geological background in western Yunnan has been summary and the origins of the polymetallic doposits were here discussed by the modern metallogenic geological theory. The article suggests that the crust structure of the Tethys arc-basin system in western Yunnan had been implemented the time-space conversion from oceanic lithosphere to the continental lithosphere structure system by complex collision orogeny and intracontinental orogenic gathers strike-slip in Mesozoic and Cenozoic. Accordingly, the metallogeny transition from arc-basin to intracontinental basin has also completed and an alkali porphyry belt was formed in the intracontinental strike-slip phase during Paleogene along the Jinshajiang-Ailaoshan length more than 1000 km.The relationship between the important minerals and sedimentary formation, intrusive rocks and volcanic rocks, and the large deformation structure in western yunnan are also summarized. Eight kinds of rock assemblage have close relations with ore-forming:1) Syenite-syenite porphyry assemblage in post orogenic stage:distributed in the Beiya tectonic magmatic section, Teso tectonic magmatic section, Zhuopan tectonic magmatic section, Saqiao tectonic magmatic section, and a lot deposits of gold, lead, iron are found in this area.2) Rich alkali granite (porphyry) rock assemblage in post orogenic stage:exists in Machangqin tectonic magmatic section, WeiShan tectonic magmatic section. A lots of metal deposits of copper, molybdenum, gold and others have been found in this area.3) Jiangfeng-Guofang metamorphic magnetite layer which occurs in Damenglong group in Jinghong county may belong to the Paleoproterozoic volcanic magmatism.4) In Cambrian strata, some medium-large sized deposits of lead and zinc, and iron have been found in Luziyuan in Zhenkang County, Shahechang and Hetaoping in Baoshan. The lead-isotope age is conformity with the geological age of the volcanic rocks in the region, it show that ore-forming materials mainly comes from the volcanic rocks in the early Paleozoic.5) the Devonian Dava Formation in Lanpin-simao tectonic magmatic zone is a set sodic volcanic rocks assemblage whose formed in continental margin arc-back and arc basin tectonic condition, some of marine volcanic-(sedimentary) type copper or lead deposits have been found in the arae, for exambles, Nanzuo lead deposit in Deqin county and Dapingzang large-scale copper deposit, etc.6) Gold is dominating mineral type what have been founded in ductile shear zone in western yunnan, such as Gaoligong mountains large scale thrust strike-slip faulting, Mengtong-Cangyuan thrust imbricated structure, Suangjiang thrust imbricated structure, Shuanggou reverse thrust imbricated structure, Tengtiao River reverse thrust-slide structure, and other large deformation structure zones. Some of them are Laowangzai gold deposit in Zhenyuan County, MoJiang gold deposit, etc.7) In post collision stage, the ore-forming elements content of gold, nickel, iron, copper and other is higher in western Yunnan. Specially, gold element can occur activation, transfer and enrichment under the condition of appropriate and favorable tectonic due to the large-scale strike-slip reformation and fluidization.8) Typical back-arc basin deposits occur on the Lanping-Simao massif, and the Dapingzhang copper depost is a back-arc basin volcanic massive sulfide (VHMS) type copper mine formed in the basin.Collecting and studing predecessors’information, this article refurbished and divided the mineralization zones in western yunnan into 2 levels II metallogenic province, and 8 levels Ⅲ metallogenic zones, and 19 levers Ⅳ ore zones. Further, the study which metallogenic geological and tectonic environment and metallogenic regularity in these metallogenic zones are carried out by the typical deposits, metallogenic models, and the regional metallogenic models and their metallogenic series and metallogenic lineage.It summarized the spatial distribution and regional metallogenic characteristics of important mineral resources in western Yunnan. Applicating GIS system, the paper sum up systematically tectonic evolution and mineralization of various geological tectonic units in the area, and discusses systematically the regularity of metallogenic events with the theory of "multi-island arc basin mineralization" and "intracontinental tectonic metallogenic transformation". such as, it explains well the formating mechanism of the porphyry copper-molybdenum deposits associated with Indosinian peoriod, and alkali rich porphyry gold copper deposits related to the Himalayan strike-slip tectonic and gold deposits of shear zone type in western Yunnan.The article also research systemically the metallogenic age and spatial distribution of the impotant minerals in western yunnan, incluse iron, copper, gold, lead and zinc, tungsten, tin, molybdenum, nickle and others. These ore deposts of different types formd in each metallogenic period from the proterozoic to the Cenozoic, and the paper puts forward some newpoints on the regional metallogenic age and its main deposits in the area:1) Proterozoic is the main metallogenic epoch of iron mineral in western yunnan, suggests that Jinghong Damenglong type and Lanchang Huimin type iron deposits are likely to belong to IOCG deposits type.2) In middle-late Triassic (whole rock Rb, Sr, K-Ar isotopic age is 214-237 Ma), it is t the most favorable area to find Pulang type porphyry copper deposits that quartz diorite porphyry assembly formed in the island arc environment of subduction zone in Pulang tectonic magmatic belts.3) The magmatic activity in Jurassic-Cretaceous age is another important metallogenic epoch in western yunnan, thery have different features that granite bodies formed in post collision stage, and thier mineralization are also different each other. Those formed in post collision stage in Jurassic-early Cretaceous occur mainly mineralization of lead, zinc, iron, copper, and the others formed in late cretaceous belong to the orogenic granites assembly and give priority to with tin, tungsten and molybdenum mineralization.4) Post orogenic tectonic background in late Oligocene, there are two kinds of rock assemblage which has interrelate and difference each other, including volcanic formations located in the Plate and in the orogenic belt. Of them, the syenite-porphyry assemblage in Post orogenic stage is favorable for gold deposits. |
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