| Duocaima Pb-Zn deposit is located in Tuotuohe area,north section of the "Sanjiang" polymetallic metallogenic belt.It is located in the promising metallogenic belt of lead,zinc,copper,silver and cadmium.The ore-forming geological information is abundant in this area,but the geological work starts late.In recent years,with the continuous progress of geological exploration,many large-and super-large lead-zinc deposits have been found in this belt,such as Mohailaheng,Ranzheyong,Dongmozhazhua,etc.,showing great prospect of prospecting.Since late Paleozoic and Cenozoic,the area has experienced multiple stages of tectonic activities,with relatively complete stratigraphic,diverse construction types,multi-group faults and fold,and strong magmatic activity.During this period,the geotectonic environment has undergone many changes,resulting in complex mineralization and diverse metallogenic types in the area.The outcrop formation in the study area are relatively single,mainly include the Permian Jiushidaoban group,Jurassic Xiali group,paleogene Tuotuohe group,Yaxicuo group,Wudaoliang group and quaternary system,among which the Permian Jiushidaoban group is the main ore-bearing strata in the area.The fault structures in the area are very developed,mainly including the regional fault zone and the parallel and strike-slip faults derived nearby,which can be divided into three groups: NWW,EW and NEE direction,among which NWW direction is the main ore-controlling structure in the area.The magmatic activity was weak,mainly intrusive,and the lithology was shallow-fleshed red quartz orthophytic porphyry,which was distributed sporadically in the late hercynian~ early indosinian.There are 7 main ore bodies in the study area.The ore bodies are distributed in nearly EW direction,and the overall shape is plate-like,partially spindle-like,with branching compound phenomenon.The main ore bodies are distributed between lines 25 and 64.The relatively rich lead-zinc ore bodies are mainly concentrated in line 3 to 36,with intermittent distribute in nearly EW direction,with length of 100-800 m,width of 1.49-108 m,thickness of 2.61-82.05 m,and concentrated in the range of 4500-4600 m.The ore body is mainly composed of zinc ore body in the western section(25-17 line)and in the eastern section(40-64 line).In the middle section(15-36 line),it is mainly composed of lead and lead-zinc composite ore body.At the same time,the zinc mineralization gradually weaken and lead mineralization gradually becomes stronger from east to west and from shallow to deep,and the crystallization degree of lead gradually becomes worse.Ore bodies are mostly found in the thin laminated argillaceous crystalline limestone at the bottom of sandstone,the limestone in the fracture zone or the highly developed limestone near the fracture zone.The occurrence state of mineralization mainly includes reticulate veins,disseminated and star point.Orebody is controllde in northwest structure and carbonate rock layers,the whole leaning north and north east prone,occurrence slower,Angle of 30°-50°.The type of ore is mainly sulfide ore.Ore mineral in the ore is mainly of galena,sphalerite,pyrite,gangue minerals are mainly calcite,dolomite and a small amount of silica,the structure of the ore mainly includes poikilitic texture,colloform texture,sideronitic texture,idiomorphic or hypidiomorphic texture and xenomorphic granular texture,show massive structure,vein structure,cavernous structure and disseminated structure.The alteration types of surrounding rocks mainly include carbonation,silicification,argillation,barite and kaolinization.Among them,silicification is closely related to mineralization and is usually produced in the form of quartz veinlets.The main ore-bearing stratum in the study area are limestone of the Permian Jiushidaoban group.Orebody is controllde in northwest structure and carbonate rock layers.The ore-forming period is Xishan period,and the genetic type is medium and low temperature hydrothermal vein type.The source of lead in the ore is complex and diverse,not only from the upper crust and orogenic belt,but also from subduction zone of crust-mantle mixing,which reveals that the ore-forming hydrothermal fluid is affected by multi-source mixing to a certain extent in the ore-forming process and has the characteristics of multi-stage and multi-source enrichment.The ore-forming fluid is characterized by low temperature,low salinity,low density,low pressure and shallow formation.Based on the comprehensive analysis of the metallogenic geological background,geological characteristics,geochemical characteristics,geophysical characteristics and genesis of the ore deposit,it is believed that the ore deposit has great potential for prospecting,and the direction and Suggestions of the next geological prospecting work are put forward. |
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