Geological Characteristics And Prospecting Direction Of Chaiwan Copper,Lead And Zinc Deposit In Dulan County,Qinghai Province

The chaiwan mining area in Dulan County is located on the eastern edge of the Qaidam Basin,and the tectonic setting belongs to the East Kunlun late Caledonian Orogenic Belt The metallogenic belt belongs to the east of the subzone of Fe,Cu,Co,Pb,Zn,W and Sn mineralization in the Eastern Kunlun metallogenic belt,Qimantage--Dulanhualixi period,which is an important polymetallic ore concentration area of Fe,Cu,Pb,Zn and Au in Qinghai Province.The polymetallic ore bodies discovered in the Caiwan mining area are mainly located in the contact metamorphism zone formed between the Triassic Lithic Crystal Tuff and the carboniferous Dagangou formation.The deposit is formed by contact metamorphism metasomatism and magmatic exhalation filling with carbonate rocks in the process of deep ore-bearing solution flowing with magmatic intrusion and overflow.The metallogenic epoch is late Indosinian.The chaiwan mining area in Dulan County is located in the area where the geological structure is complex and the magmatic activity is strong.As a result,the older strata are often destroyed or eroded,resulting in sporadic strata in the area The strata of lower carboniferous Dagangou formation?C₁dg?and upper triassic elashan formation?T₃e?are exposed.The strata in the mining area developed interlayer structure and joint because of the action of regional principal stress,which provided good ore-guiding channel and good ore-storing space for the migration and metasomatism of ore-liquid and the main ore-storing structure in the mining area.The intrusive rocks are not well developed,the volcanic rocks are well developed,the rocks are Lithic Crystal Tuff,and the micronutrient content in the rocks is high,which provides the main material source for mineralization.The surrounding rocks of ore bodies are mainly Tuff,siliceous carn,silicified limestone and marble.The ore-bearing lithology is mainly sicarn,marble and limestone.The Wall rock alteration is mainly SICARNIZATION,followed by hydrothermal alteration.The ore body is controlled by magmatic lava,Wall rock alteration and interlayer fissure.According to drilling engineering,2 mineralized zones are delineated in caiwan mining area.The I mineralized belt is 720 m long and 5⁴0m wide,with a general dip to the south-west and an inclination of 55⁷5.There are seven polymetallic orebodies in the inner belt.The orebodies are 50⁵72 m long and 1.06⁸.83m thick.SPHALERITE is the main ore,Galena,chalcopyrite and magnetite are the second The average grade of Zn,Cu and Pb is 3.41%,1.54%and 0.5%,the length of the second mineralization belt is larger than 200m,the width is 15²0m,the occurrence is 0.46,and two polymetallic ore bodies?all controlled by single project?,the thickness of the ore body is 1.15¹.21m The length is 200m,the depth is more than 100m,and the ore species are Fe,Pb,Zn.The average grade of Zn,Pb and Fe is 1.69%,0.60%and 22.17%respectively.The main ore minerals are sphalerite,magnetite,Galena and Chalcopyrite,followed by Cerusite,arsenopyrite,pyrite,pyrrhotite,Limonite,stibnite and native copper.Gangue minerals are mainly calcium garnet,calcite,quartz,plagioclase,epidote,chlorite and biotite.The mineralogenesis of the mining area is characterized by multi-period,with mutual replacement,interlacing and continuity,closely related in time and overlapping in space.The ore structure in the mining area mainly consists of its shape-like granular structure and metasomatic structure,followed by self-shape-like semi-self-shape granular structure,emulsion-drop structure,inclusion structure and colloidal structure The main structures are disseminated structure,massive structure,vein structure,strip structure and star structure.The surface of the mining area is covered with large quaternary,and the prospecting indicator in the area is mainly silicon-carpeted zone.The contact zone between the early carboniferous Dagangou formation and the triassic volcanic rocks of the Erashan formation is a favorable section for the exploration of silicon-carpeted zone The diopside and cartonization areas in the silicon-cartonite belt are the favorable areas for the exploration of polymetallic ore bodies.The orebody is mainly controlled by the interlayer fracture zone,and the structural fissures and joints are the main storage space of the ore body,which is the beneficial section to find the larger ore body.Three magnetic anomalies were delineated by 1:5000 high-precision surface magnetic method in the mining area,and verified by drilling engineering,3 anomalies were confirmed to be ore anomalies caused by iron,lead,zinc and copper.The mineralized belt discovered in the area is mainly located in the buffer zone of positive and negative geomagnetic anomalies in magnetic survey.The buffer zone is mainly distributed in the central and western part of the mining area,extending in a NW direction The strike direction of the contact zone is basically consistent with that of the Triassic Erashan Formation Tuff and the lower carboniferous Dagangou formation rock.Therefore,the buffer position of positive and negative geomagnetic anomalies in the area is a good target for prospecting cu-pb-zn polymetallic deposits.The magnetic anomaly buffer zone west of line 49 in Chai Wan Mining area is the next prospecting direction.In addition,it is one of the important prospecting directions for the main ore bodies discovered along the inner edge of the mining area to continue tracing.