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Characteristics Of Subcrystalline Petrochemicals And Deposits Of SSC Cu - Ag Deposits In Baiyang Plant, Northwest Yunnan, China

Posted on:2016-04-22Degree:MasterType:Thesis
Country:ChinaCandidate:W B ZhuFull Text:PDF
GTID:2270330482468495Subject:Geological engineering
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Baiyangchang Cu-Ag deposit is located in the southern-middle section of Lanping Mesozoic-Cenozoic basins in Yunlong county, northwest Yunnan. A small amount of forefathers’research work indicates that the Cu-Ag deposit belongs to the percolation hot brine epigenetic stratabound ore deposit (He Wenju.1987), or sedimentation-reformation ore deposit (Lifeng, 1991). However, the survey found that there are many misunderstandings on the formation and tectonic geological conditions of the mining area, and the special characteristics of Cu-Ag deposit mineralization and formation mechanism has not yet been revealed. Based on the strata, structure, mineralization and alteration mapping, this paper finds out basic geological characteristics of Cu-Ag (body) deposit and its metallogenic epoch. Besides, the paper points out the development characteristics and space-time distribution of baritization, establishs the structure model of mineralization-alteration of deposit, and analyzes the deposit genesis by using structure and lithofacies alteration mapping, lithofacies and isotope tracer analysis.The paper obtains the following awareness and conclusions:(1) The structure of mining area mainly consists of syndepositional depression belt characterized with nearly north-south anticline, syncline and the development of normal fault, local associated nearly east-west small fault set, structural collapse body and sand or mud diaper with gypsum. The outcrops consist of sand-mudstone of upper cretaceous Nanxin formation, Hutoushi formation and paleocene to eocene Yunlong formation which develop multi-level soft sedimentary structure layers. Nearly north-south F1 fault is main growth fault(2) The known ore bodies are occurrence to light lithic feldspar quartz sandstone and light sandstone breccias in rubble breccias belt of Hutoushi formation presenting impregnated or veinlet-like, accompanying strongbaritization weakcalcilization and gypsification. The organic combination of stratigraphic lithology, fold deformation, structural collapse body and sand or mud diaper with gypsum controls the ore-forming fluid migration and precipitation of metallogenic Cu-Ag deposits in this area. The mineralization process can be divided into the diagenetic mineralization period.hydrothermal mineralization period and supergene enrichment period.(3) Baritization forms from center to edge of ore bodies, and its occurrenceare spotted, fine veins and rough vein structure. Bsides. we Identify the relationship between baritization and associated metal sulfide mineralizationandcalcilization.(4)The analysis results show that the sulfur source of Baiyangchang Cu-Ag depositare from multiple sources properties, and display a complex isotope fractionation process. Lead source has obvious shell source characteristics. Strontium from sedimentary rock strata. Ore-forming fluid has the characteristics of multiple sources and mixed fluid.(5) This ore deposit belongs to the SSC type deposit which is controlled by synsedimentary deformation in sedimentary depression belt. The Cu-Ag deposit formed in the late stage of Hutoushi to the late stage ofYunlong (the late cretaceous (K2) to earlypaleogene (E1-2)), which is the product of mixture of deep concentration H2S drainage fluid and lake water or basin brine in the evolution process of regional extensional basin to the strike-slip pull-apart basin.(6) Put forward the favorable prospecting target areas of Baiyangchang mining area are the south area, Among them.important prospecting indicative marks are spots and fine vein of barite, calcite and gypsum in upper Cretaceous light sandstone.
Keywords/Search Tags:baritization, geologic feature, SSC type ore deposit, Isotope tracer, Ore deposit genesis, Baiyangchang Cu-Ag deposit, Lanping basin
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