| Mengnuo Pb-Zn deposi is located in syncline's East Wing,Mengnuo Town,Longling County,Baoshan City.The deposits are mainly distributed in nearly north-south-trending,it is obviously controlled by stratum,lithology and structure.There is almost no research on the construction of ore-controlling areas.In this paper,based on the weak links in the study of the mining area,on the basis of summarizing predecessor data and a large number of field geological surveys,completed the analysis of the structural features of the mining area,the evolution of the tectonic stress field in the mining area,the division of the structural period,and Different types of structure ore control,the relationship between tectonic stress field evolution and mineralization.And establish a tectonic-sedimentary-mineralization model and a tectonic-magmatic-mineralization model of Mengnuo mining area.The paper mainly achieved the following points:1?Through the observation of field geological phenomena,the identification results of indoor polished thin sections,and the overall screening experiment results of lead-zinc grades,the ore-forming process of the deposit is divided into two periods: hydrothermal-exhalation sedimenta and struction-hydrothermal period.2?In the mining area,there are mainly folds,interlayer fracture zone,faults and joint structures,which constitute the fold-fault-interlayer fracture zone and joint(fracture)structural system.There are developments in fractures and joints in all directions in the mining area,but the fracture structures in the near SN and near EW and the interlayer fracture zone are the most developed.The structures in different directions show different mechanical characteristics and tectonite feature,while the structures of different types in the same direction show the same mechanical characteristics.3?The distribution of ore deposits in the secondary Mengnuo syncline control region of the Baoshan-Shidian multiple syncline southern section;the F10 fracture near the SN direction is the main ore-forming structure in the mining area and controls the distribution direction of the ore body;the second-order fracture obliquely intersecting with the SN-striking faults is the ore-distributing structure in the mining area,and controls the space-production site of the ore body;the interlayer fracture zone is the main ore-bearing structure of the mining area and controls the output characteristics of the ore body;the near EW-trending and NW-trending fault structures are post-mineralization structures,which have a destructive effect on the ore body.4?The tectonic stress field of the mining area mainly experienced the evolution process of east west compression-east west extension-south north extension-north east compression,and based on this,the evolutionary process of tectonic stress field is divided into three evolution periods: pre-mineralization,main mineralization and the post-mineralization periods.In the pre-mineralization period,it is compressed by EW-trending,resulting in near SN transpressional structures and interlayer sliding belt;In the main mineralization period,it is compressed by near SN-trending,and superimposed transformation resulted in the formation of SN torsional fracture and interlayer fracture zone;In the post-mineralization period,EW-trending stress formed near EW and NW fractures,and NE-direction stress causes SN-fracturing strike slip.The ore body mainly forms in the EW extensive stress stage.5? The pre-mineralization structure formed the mineralization geological background of the Mengnuo mining area,the deep-circulating fluid extraction of the basement strata mineralbearing and then sedimentated in the low-lying reefs after the restricted basins,the Silurian Xirenheqiao Formation sedimentary formation formed,the tectonic-sedimentary-mineralization model that constitutes the sedimentary diagenetic period.The mineralization period(Yanshanian)structure not only formed a syncline,a fault,but also led to the emplacement of deep magma,which magma provides minerals and heat for deep-circulating atmospheric precipitation,constituting magmatic ore-bearing hydrothermal fluids.The tectonic-magmatic-hydrothermal-mineralization model during the hydrothermal reformation period is formed under the action of the fold-fault-interlayer fracture zone and fissure structures system,guided,transported,moved and stored. |
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