Geological Characteristics And Deep Prospecting Prediction Of The Zigangping Lead-zinc Deposit In Jiulong County,sichuan Province

By years of mining,the mine resource of Zigangping lead-zinc deposit in Jiulong County,Sichuan Province runs short.Due to previous work paying much more attention to production than metallogenic theory and prediction,makes the next step in the mine exploration into the bottleneck.This study through ascertaining deposit geological characteristics,disscusses ore deposit genesis and controlling factors,and by the method of primary halo,forecasts prospecting scientifically and provides important guidance to prospect in depth and outside and expand the resources reserves in the future.The tectonic unit of mining area is located in the southeastern coast of Songpan-Ganzi geosyncline fold system,namely in Jiulong anticline of Ya River miogeosyncline fold belt.Meanwhile,it's located in the northern section of Sichuan-Yunnan north-south tectonic belt and in the west wing of Dichi mountain anticline of east Ganzi-Muli geosynclinal fold belt.The emergence stratum mainly is the regional metamorphic rock series in low-medium temperature of Lower Permian Jiahuang Groove Group second and third members,with lithology given priority to quartz schist and mica schist,etc.There finds out two main faults and monoclinal formation in the region.There is no magmatic rocks outcropped in the mining area,but mica granite is widely distributed about 2 km in the north of the end of Dichi mountain plunging anticlinal core.A pb-zn orebody found in the mining area,number for ?,occurs in an interlayer fault between pomegranate plagioclase biotite quartz schist in the fifth layer,second member of Lower Permian Jiahuang Groove Group(P₁jh^2-5)and pomegranate albite mica quartz schist in the sixth layer(P₁jh^2-6),as stratoid beds,having the obvious stratabound characteristics.Through investigating the ore body size,shape,occurrence,internal structure,thickness,grade and change characteristics in detail,finds out the scale of ore deposit reaches medium-sized,and the orebody occurs stablely on the plane and section like a gentle wave which extends 1280 m in length,1447 m in depth,180 240° in the tendency,overall about 210°,and 40 60° of general inclination,average 54°.The average thickness is 0.82 m and the average grade is 2.71% for Pb,8.01% for Zn.The orebody is much slightly influenced by structure and keeps an excellent continuity.Ore textures include xenomorphic granular texture as primary,partial crushed brecciated texture,few automorphichypidiomorphic granular texture,metasomaric texture,emulsion texture and parcel texture,etc,while structure is given priority to disseminated structure,time for the massive structure,banded structure,vein structure.Mineral composition is simple and ore minerals consist of a large amount of pyrite,sphalerite,partial galena,a small amount of chalcopyrite and other trace metal minerals.Main beneficial elements are zinc,lead and associated useful components are mainly silver,copper,cadmium and sulfur.Natural ore type belongs to sphalerite pyrrhotite ore and industrial type belongs to primary sulfide ore in a single.Near-ore wall rock alterations are mainly pyrrhotite,ilmenite,silicide.A small amount of barren rocks don't break the continuity of the orebody.Through the detailed study of mineral assemblage,distribution characteristics,intercalated relationship between ore vein,recognizes the mineral crystallization has many stages.Ore-fabric characteristics also reflect a variety of genetic types of ore bodies.Confirmed with the geological characteristics of Zigangping lead-zinc deposit,divides four pulses of mineralization including the sedimentary mineralization,hydrothermal alteration,regional metamorphism and supergene.By discussing the metallogenic mechanism and process,considers that firstly ore body formed a banded ore source bed in the sedimentary diagenetic stage,and then with the hydrotherm which is probably provided by Yanshanian mica granite located in Dichi mountain anticlinal core,in the north east of mining area injecting in along the interlaminar slip fault by reason of the schist rock plastic deformation,the ore source experienced hydrothermal modification consist of low sulfide phase,polymetallic phase,pyrrhotite phase,residual heat fluid phase,and finally formed the main ore body represented by disseminated ores.By researching and summarizing the geological characteristics of Zigangping lead-zinc deposit systemically and compared with the similar and adjacent mineral deposits,considers it as a hydrothermallysedimentary reworked deposit.The geochemical characteristics of ore deposit shows main metallogenic indicator elements are Pb,Zn,Cu,Co,Ag,Sb,Hg,and secondly are As,Sn,Mo,Ni,Bi,W.The primary halos distribution shows in a single stage of mineralization,As,Sb,Hg are the front halo indicator elements,Pb,Zn,Ag,Bi,Co near ore,Au,W,Mo,Cu in lower and tail.The comprehensive axial zoning sequence of primary halos is As?Sb ? Ni ? Bi ? Ag ? Ba ? Zn ? Sr ? Mo ? Au ? W ? Co ? Pb ? Sn ? Cu ? Hg,appearing the opposite zoning direction.The axial trend evaluation indexes of geochemical parameters changes from big to small and turning big again,indicating obvious superposition and the contents of front halo elements Ag,Sb,Hg shows an increase tendency in the lowest midsection.So speculates that the ore body has a very large percentage to concentrates and expands at relatively distant locations again.Establishing the deep orebody prediction model,combined with ore-forming indicator elements concentration distribution,forecasts the form of orebody in the deep is cystic and the orebody may expands again in the bottom of P08-P16 exploration line,otherwise has a tendency to gradually annihilated in the east and west.