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Study On Metallogenic Condition And Potentiality Of Copper-Gold-Polymetallic Deposits In Weishan-Yongping Mineralization District, Yunnan

Posted on:2004-07-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:F L DongFull Text:PDF
GTID:1100360092996482Subject:Mineralogy, petrology, ore deposits
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The district studied is located in the southern portion of Lanping basin in the middle of Sanjiang area. As we know, lots of large and supper-large deposits have been discovered in the northern part of Lanping basin. However, the deposits known so far in both quantity and size in south part of the basin are not adequate with respect to its favorable metallogenic settings. Therefore, it is essential to evaluate the metallogenic potential of Copper-Gold of this area by conducting a systematical research on the regional magma-fluid-metallogenic system. A combinational method of regional fluid geology mapping combined with other methods under the instruction in the theory of "magma-fluid-metallogenic system" has been employed to find out the mineralization condition and potential including the size of distribution area of ore-forming fluid.The main progress after three years field investigating and indoor research work are summarized as follows:1. A regional metallogenic model has preliminarily been established on the basis of systematical studies on the regional metallogenic condition and control factors of copper-gold deposits at Weishan-Yongping mineralization district. The author suggests that the three lithosphere-scale faults, Lancangjiang fault, Jinshanjiang-Ailaoshan fault and axis fault in the middle of the basin, are the main geological structures that control the formation of basin, magmatism and metallogenic congregate district. The anticline structure with an axis of Triassic strata and the related fault system within the basin, and Gonglang arch-shaped folding structure in the south of the basin are the geological structure controlling the formation of ore fields. Junctions of two or more faults with different orientation, interlayer cataclastic structural zone and oxidation-reduction (Redox) boundary were the favorable position for the formation of ore bodies. A great deal of statistic data illustrates that the Mesozoic strata, especially the Upper Triassic immature sediments, are presumably an important source of ore-forming metals.2. 38.6Ma and 36.7Ma isotopic ages of quartz-monzonite-porphyry in Lianhuashan and alkaline porphyry in Zhuopan have respectively been obtained. Those results are consistent with the ages of the porphyries in both Lanping-Shimao basin and Changdu basin related igneous rocks, representing the first episode (Lanping movement) of tectonics-magmatism-metallogenic event during the Himalayan movement. K-Ar age of an illite from alteration rock in the contact zone around Lianhuashan porphyry is 38.6Ma. With referencing to the main metallogenic period of Yulong copper metallogenic zone and of Ailaoshan gold metallogenic zone, it is suggested that the time of formation of deposits in the district studied is probably in a period of time from 38.6Ma at earliest to 20Ma at latest. This time is equivalent to the origination time of two important tectonic events, i.e., Lanping movement and the turning point when Ailaoshan-Red river fault turned from sinisteral into dextral. It is argued that the magmatic activities of quartz-monzonite-porphyry and alkaline porphyry presumably played an essential role in mineralization of this district, that is, the porphyry system could be important sources of both ore-forming metals and ore-forming fluids, as well as a thermal engine that drived cycling of metallogenic fluids. The research shows that mineralization fitted well with the regional tectonic-magmatic- metallogenic events and deep structure in this district.3. Based on distribution of deposits and types and characteristics of mineralization, twomineralization zones could be divided. From west to east they are Yongpingchangjie-Shuixie-Nanjianxinmin middle-high temperature copper-cobalt mineralization zone and Zijinshan-Maanshan-Bijiashan middle-low temperature Au-As-Sb-Hg mineralization zone. The types of deposits in the former are high -middle temperature and middle-low salinity hydrothermal copper-cobalt deposits, and high -middle temperatur...
Keywords/Search Tags:Copper-Gold- Polymetallic Deposits, metallogenic conditions, and metallogenic potential, southern of Lanping basin, Weishan-Yongping district, Yunnan
PDF Full Text Request
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