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Geological Characteristic Of Lead-Zinc Polymetallic Deposit In Medro Gongkar Country,Tibet

Posted on:2010-11-03Degree:MasterType:Thesis
Country:ChinaCandidate:X L CuiFull Text:PDF
GTID:2120360278460583Subject:Mineralogy, petrology, ore deposits
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The east segment of Longgeer-Nianqingtanggula magmatic arc is delimited by Dangxiong-Yangbajing fault in the west,Yongzhu-Jiali-Bomi suture zone in the north and east, and Shamole-Luobadui-Milashan fault in the south. The magmatic activity in this region was very fierce and frequent. Either volcanic or granitoid rocks are widely present. In addition,since Late Paleozoic,this area has been characterized by extensively distributed carbonate-clastic rock associations sedimentated from shallow sea,epineritic environment,marine-continent exchange environment. All of these exceptionally geologic conditions contributed significantly to the formation of Skarn deposits.Dongzhongla lead-zinc polymetallic deposit is located in the south margin of east Longgeer-Nianqingtanggula magmatic arc, in the junction of the Longgeer- Gongbo'gyamda fault-uplift belt and Gangdise-latter Zayülater Yanshanian-Himalaya magmatic arc, falling into the Nianqingla-Shangchayu Pb-Zn(Cu)-Fe mineralized sub-zone. Nyainqentanglha Mesozoic island-chain uplift belt is mainly the Preordovician strata, developed a number of stages of acidic intrusive rocks, the fault constructions are nearly east-west tendency reverse faults, the region experienced a number of stages of various types of metamorphism. In the Carboniferous-Early Permian, as formation of the Pangong Lake-Nujiang Tethys, there was deposited he clastic rock terrane containing a inland bimodal volcanic rocks in the eastern section of the fault-uplift belt, including the Nuocuo group(C1n) , Laigu group(C2-P1l). In the Permian, this area firstly changed from a passive continental margin into an active continental margin, and deposited a suite of the carbonate formations-Luobadui group (P2lb) including a bimodal island-arc volcanic rocks. Conducive to the formation of skarn rocks are mainly limestone, bio-limestone, marl, rich-calcareous mudstone, volcanic tuff, etc. CaO, CO2 and other components in the carbonate formation had important impact for the formation of skarn. Magmatic rocks in the region greatly developed, mainly formated in the Himalayas and the Later Yanshanian. Yanshanian magmatic rocks were intermediate-acid rocks, and the Himalayan magmatic rocks were main acid rocks. The magmaticbodies related to mineralization were mainly the Cenozoic quartz adamellite, quartz second and adamellite (porphyry), hornblende biotite monzogranite, etc.During the research, the geological features of dongzhongla polymetallic lead-zinc deposit is studied in detail. On the basis of analysis of ore-controlling factors such as strata, structure, and intrusion body, combined with the regional research achievements,the origin of deposit is discussed preliminarily.Studies have shown that,along the strata to the extent ,the characteristics of lead-zinc mineralization was sub-concentration in the mining area.In the centralization area of the mineralization,the shape and attitude of the orebody was controled by the wallrock. it shows the characteristics of strata-bound. But the fault located in the central part of the mineralization area is the mine fluid migration pathway.The deposit developed a series of hydrothermal alteration.Industrial orebody occurred in the strongly altered area. The deposit had the characteristics of multi-stage stack.Based on the structure background of the deposit output, as well as the rock environment of the orebody position, it preliminarily viewed that the deposit belong to the skarn-type lead-zinc deposit.
Keywords/Search Tags:Gangdisi metallogenic belt, Skarn-Type, Dongzhongla Lead-Zinc Polymetallic Deposit, Geological Characteristic of Deposit
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