Geological Characteristics And Genesis Analysis Of The Heishaishanshan Lead-zinc Deposit, Yunnan Province

The mineralization of DaHeiShan Pb-Zn mine is located in the Three Rivers metallogenic belt,south of Chang Ning-Meng Lian rift belt.Belonged to the Chang Ning-Meng Lian and the early carboniferous metallogenic belt.It's good for looking for Lao Chang type of volcanic activity related to silver lead-zinc polymetallic favorable target areas.But this region in addition to the Lao Chang silver lead-zinc mine for super-large ore,found no significant ore deposits.In this area,at the present,DaHeiShan Pb-Zn deposit has the certain breakthrough prospecting,but the degree of researching is low,nobody has done systematic working.Nobody has researched about the metallogenic geological background of ore deposit,geology metallogenic substances and the ore-forming fluid,either.Therefore I depend on my teacher's cooperated company's setting up project of DaHeiShan silver lead-zinc mine detailed investigation exploration working,choosing the tunnel's exposed,high grade samples of ore and the exploration engineering for main researching project.Through field observations,gallery catalog,sample collection,light thin slices' microscopic identification,geochemical analysis work and so on.I came to the conclusion that:(1)Layers exposed in the mine lot form old to new mainly include the southern group of lower carboniferous,the upper carboniferous,the HuiXing group of lower Permian,the JingMao group of lower permian and the quaternary system.Among these layers the southern group of lower carboniferous and the upper carboniferous are the main ore-bearing bed.The lithological characters mainly are grey-pale thin-level dolomite,thick-massive dolomite,fine sand stone.quartz sandstone,limy dolomite,bio clastic limestone including dolomite limestone and so on.The structure of the exploration mainly is fold and fracture.Most of the fracture and the fold have the east protruding arc characteristics,forming arc drape structural belt.The tectonic line of the north of the couple is north west trend,the south part is north east trend.SO DaHeiShan is located in the north east of the LaBa secondary arc structure.The structure mainly are the north east fracture and the north west fracture.The district is divided into fault block sizes.And the distribution form of formation in this area is controlled by the structure.The north east fracture,F1,is the ore bearing structure and the ore-controlling structure of the mine lot.It has relatively large size,the rest of the size are smaller.(2)The ore bodies are mainly controlled by fracture.Tow layers of the ore bodies'output are rrespectively in fault zone and its adjacent part and parallel in rich manganese carbonate belt.The ore bodies exposed in the project mainly are red oxidized ore.brown oxidized ore and A maroon oxidized ore.And contains some sulfide ore.Most of the output are brecciated structure,infect structure,vein structure and vein structure.The plate of the ore body's surrounding rock is mainly consist of dolomite,rich manganese carbonate.the footwall of the ore body's surrounding rock is mainly consist of muddy phyllite,sandy slate.The ore mineral composition is simple,the main mineral is sphalerite,galena,pyrite,and contains a small amount of chalcopyrite.The main wall rock alteration is calcilization and ferromanganese carbonatized.the second is dolomitization.faded and chloritization.(3)Selecting elected ore minerals of sphalerite.galena and calcite for stable isotope analysis.The result of sulfur isotope analysis shows that the sulfur of the mine area mainly comes from deep mantle source.The result of lead isotope analysis shows that the main output of lead is in the earth's crust and orogenic belt in the mixed zone,belonging to the shell source.The carbon and oxygen isotope analysis results show that the ore-forming fluid is derived from magmatic hydrothermal deep mantle source,containing a small amount of atmospheric precipitation and sea water.The trace element analysis result shows that the deep mine area there may be a granite porphyry,the ore-forming fluid has a deep origin.The rare earth element analysis shows that the ore-forming fluid comes from the hidden intrusion at depth,with a high temperature,drived by the magma thermal.It's similar with common porphyry deposit.(4)DaHeiShan's metallogenic model is very similar with LaoChang's shallow orebody characteristics of porphyry metallogenic model in the same mine area of the three rivers metallogenic belt.The ore-forming process can be outlines as:in the neo-tethys stage,at the beginning of the end of the cretaceous-paleogene period,the ocean basin of the Yarlung Zangbo River closed.the Indian subcontinent collided with Eurasia.Later,as it continued to move north of the Indian plate and Eurasia reverse blocking effect,the northward intracontinental subduction of Indian continent happened,causing the earth's crust shortening and thickening,the rise of Tibetan plateau and crustal material flowing east.With the effect of two-way extrusion of Indian subcontinent and Eurasia,the three rivers region came into comprehensive intracontinental tectonic phase adjustment.the activity of fault and magmatic fluid were very active,large-scale mineralization happened during this time.In LaoChang and DaHeiShan area the porphyry metallogenic series formed with granite porphyry intrusion.