| The Chuduoqu polymetallic deposit is located in the northern the northern Qiangtang-Changdu block of the Late Paleozoic-Early Mesozoic suture zone of Kekexili-Jinshajiang,in the back-arc foreland basin of Yanshiping,occupying Xiaotanggula Mountain,and undergoes the Himalayan tectonic activation of intracontinental orogeny,which caused the Jurassic system to be subjected to intense folding and faulting,forming a young orogenic belt,accompanied by intrusion and mineralization of acid magmatic rocks.The study area is located in the back-arc foreland basin of Yanshiping.The stratum outcrop is relatively single.It is mainly composed of the upper-middle Jurassic Yanshiping Group,the lower Cretaceous Cuojuri Group and Quaternary,with strong tectonic and magmatic activities.Affected by the nearly EW and NS faults,the axial direction of regional folds(synclines)is NW-SE,there are axial NNE trending folds in the east of the study area.The faults in the mining area are well developed,mainly regional NW and NE faults,which provide a channel and space for the later migration and occurrence of ore-bearing hydrothermal fluid.The two groups of faults are derived from the near EW and near NS faults,which are the main ore hosting structures.Seven mineralization alteration zones have been delineated in Chuduoqu mining area.Three of them,SB V ~ SB VII,are generally NW-trending and controlled by regional faults in this direction.SB I ~ IV four generally show a nearly NE-trending,which is a secondary interlayer fracture.The alteration of wall rock is mainly barite,carbonation and silicification,and mineralization is mainly galena.There are 11 polymetallic orebodies in the mining area,including four Lead-zinc-silver orebodies,four lead-silver orebodies,one lead-copper-silver orebody,one copper-silver orebody and one lead orebody.The main ore minerals in the study area are galena,sphalerite,chalcopyrite,galena,pyrite,limonite and specularite.The gangue minerals are barite,quartz,calcite and a small amount of sericite.Most galenas in ore bodies are metasomatized by gangue minerals,and are transformed into remnants of different sizes.The margins of galena minerals are metasomatized unevenly.Some galena crystals are also metasomatized by gangue minerals,resulting in a uniform distribution of some residual galenas in the ore in a network form.Sphalerite usually shows irregular or granular.The results of high-precision magnetic survey(1:10,000)are as follows: the background magnetic field in the north of the study area is mainly negative,and its intensity is between-10 and-50 nT,whereas in the south,it is mainly positive,and its intensity is between 10 and 100 nT,and the macroaxis of magnetic anomaly distributes nearly EW-trending,which basically coincides with the geotectonic characteristics of the area.Six magnetic anomalies have been circled in this work.Among them,C2 and C3 anomalies have the largest area,towards the near east-west direction,the range of anomalies ranges from-70.1 nT to 100 nT,and the trend coincides with the SB V ore-bearing alteration fracture zone.It provides a basis for prospecting in the mining area. |
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