Research On Spatiotemporal Zonality Which Mineralization And Alteration And Its Prospecting Applications Of Liangyan Lead-Zinc Deposits In Hezhang,North-Western Guizhou Province

The Liangyan Pb-Zn deposit is a more than medium scale deposit explorated recently in the northwestern Guizhou lead-zinc metallogenic belt of the Guizhou-Yunnan-Sichuan lead-zinc metallogenic domain,and still has much more mineral potential.Deposit is located on the plate of the yadu-mangdong thrusts,the south east anticline.The ore bodies occurred in dolomitic limestone and dolomite suffering intense dolomitization within middle Carboniferous Huanglong Formation,it showed obvious mineralization features of MVT,In this paper,based on three-dimensional alternation-lithofacies mapping and petrographic studies of No.I ore body group,With the means of hydrothermal mineral typomorphic and isotopic geochemistry tracing method,find out the alteration and mineralization,reveal its mineralization process and controlling factors,establish its zonation patterns and genetic model,and proposed the exploration target area,and contribute to unders-tanding of the migration,concentration and enrichment of ore-forming fluids and great indicating significance for the prospecting of mineral resources in the Guizhou-Yunnan-Sichuan lead-zinc metallogenic domain.The main achieve the following results and knowledge:?1?System to identify the stratigraphy,structure and geological development characteristics of mining,In this area,yadu-wogong anticline is the ain anticline,the anticline was destroyed by yadu-mangdong fault,anticline axis near NW trending,the North East Wing strata exposed incomplete,only exposed Longtan formation of upper Permian?P₃l?,formation tendency North East,gentle inclination,generally 10 °?25°,South Western exposed strata more complete,core Department to wing dominated Paleozoic strata,followed by shangsi-jiusi formation of lower Carboni-ferous?C₁j+s?,datang formation?C₁d?,huanglong formation?C₂h?of middle Carboni-ferous,maping formation?C₃m?of upper Carboniferous,liangshang formation?P₁l?of lower Permian,qixia-maokou formation?P₁q+m?,emeishan basalt formation?P₂e?of middle Permian,longtan formation?P₃l?of upper Permian.formation tendency South Western,formation dip between 30°?45°.Followed jiaoding Mountain syncline,the axis near the north-east,exposed strata are datang formation?C₁d?of lower Carboni-ferous?C₁j+s?,,huanglong formation?C₂h?of middle Carboni-ferous,maping formation?C₃m?of upper Carboniferous,liangshang formation?P₁l?of lower Permian,qixia formation?P₁q?,formation dip between 16°?30°.The main fault for a reverse fault is F₁,tendency near SW trending,dip between 45°?60°,cutting depth,breaking away from the more than Ikm.The tendency of F4 for a reverse fault near SW trending,dip between 45°?60°,F₁ and F4 belong the branch of yadu-mangdong fault.In this area,imbricated thrusting of F₁ and F4 maked yadu-wogong anticline and jiaoding Mountain syncline composite parts are the most favorable position for the district lead-zinc-enriched,the ore body concentrated in secondary faults and fractures of regional fault in the area,mostly bedded,lenticular bedding output,Among them,No.? ore produced in the Lower Carboniferous Datang formation coarse crystalline dolomite and Huanglong formation fine-coarse crystalline dolomite that the plate of F₁,Consist of stratiform orebodies that Small-angle intersects with formation and cystic branch orebody of the subjacent,The main orebody in vertical distortioned,upper tended to SE,lower tendency to SW,dip Angle between 44°?71°,main ore control oblique deep greater than 150m,generally thickness of 2?6m,average thickness of 3m,high ore grade,generally,Pb 2%?0%,Zn 4%?30%.No.I ore produced in the Huanglong formation fine-coarse crystalline dolomite that on the plate of F₁,tendency NE,dip 54°?⁵7°,main ore control length 80m?100m,the tendency to extend 60m,generally thickness of 1.2-1.4m,average thickness of 1.3m,the ore grade is generally Pb 2%?3%?Zn 3%?7%.The ore mineral assemblage are sphalerite,galena,pyrite,sphalerite,chalcopyrite,a small amount of marcasite,chalcopyrite,etc.Gangue mineral assemblage are calcite?Cal?,iron-calcite?Fe-Cal?,dolomite?Dol?and a small amount of quartz?Q?,siderite?Sd?,bitumen?Org?,etc.Wall rock alteration is mainly pyrite,dolomitization,calcite,iron and manganese carbonation and silicification,Closely with Pb-Zn mineralization,Hydrothe-rmal mineralization can be divided:?I?Dolomite-?pyrite?stage,???Dolomite-sphalerite?red?-galena-pyrite?-quartz?-calcite stage,?III?Dolomite-sphalerite?brown?-galena-pyrite?-quartz?-calcite stage,???Dolomite-sphalerite?sepia?-galena-pyrite?-quartz?-calcite stage,???calcite stage,Which ?,?stage is the main mineralization period.?2?Find out the mineralization-alteration zoning characteristics of the Dajie Mining area,The results indicate that the alternation zoning from the center of ore bodies outwards is calcitization?dolomitization?silicification ?chloritization,Correspondingly,the mineralization zoning changes from massive mine-Ralization zoning changes from massive,breccia ore?massive pyrite shell?disseminated-vein-patchy low-grade ore?vein-starry pyrite shell,The mineral assemblage zoning can be divided into Sp+ Gn+ Py+ Apy+ Cal+ Q+ Ill?Py+ Gn+Sp+ Dol+ Cal+ Fe-Cal?Py+ Dol+ Cal?Py+ Q+ Chl+ Cal assemblage.Overall,The horizontal zoning is well developed,whereas the vertical zoning is not significant,which is related to the effect of the concentration gradient of vertical physical changes of orebearing hydrothermal solution and lithology.Mineralization-alternation can be divided into five stages,Red sphalerite and pyrite is the product of early fluid,Brecciated ore is the product of fluid superposition,The temperature of the fluid to form Brown sphalerite of ??? stage is higher than that the red Sp of ? stage.The 1750 meter level is the ore-forming fluid superimposed striker,but the Alteration-mineralization zoning mechanism of the deposit different from the northeast of Yunnan lead-zinc metallogenic belt as Mao Ping large Pb Zn deposit.?3?Summarizes the typomorphic characteristics of the different mineralization-alteration zone within dolomite,pyrite and sphalerite and other hydrothermal minerals.establish its mineralization-alteration zonation patterns?In the space:the alternation zoning dolomite from the center of ore bodies outwards is Massive coarse-grained?Massive,vein fine-grained,Pyrite changes from pyritohedron and its combination form to cube and its combination form.Monomorphic changes from {210}to {100}.With the elapse of time,he alternation zoning dolomite from the center of ore bodies outwards is coarse-grained?fine-grained,Pyrite changes from pyritohedron to cube,early sphalerite mainly in red,late mainly brown;Reaction deposit is in epithermal deposits and From early to late stage mineralization temperature increased first and then decreased.?4?Identify the origin and evolution of the ore-bearing fluids,C,O,S and Pb isotopic composition studies show that ore-forming fluids and substances with multi-source characteristics,Sulfur may be an early role in the formation of bacterial reduction,with the ore fluid temperature gradually increased,S of ore fluids mainly by the sea thermochemical sulfate reduction.In the reduction process,the underlying shale,clastic and pelitic rocks organic matter plays a certain role.The CO₂ of host rock may be concerned with the thermal power from emeishan basalt magma.CO₂ of early stage from hydrothermal calcite mainly formed of a low-temperature alteration,as the ore fluid temperature rises,the latter hydrothermal calcite mainly for marine carbonate provided,the ore-forming metals come mainly from the carbonate strata,similar with the studies of the sphalerite typomorphic that early low temperature,the temperature gradually increased and then reduced the late.Metal mineralization derived from the upper crust?similar with the different age carbonate rocks and basement rocks lead isotopic composition in this area,significantly different from the Emeishan and Sinian Dengying lead isotopic composition?,with multi-source characteristics.?5?Summarized the ore-forming process of Pb-Zn deposits in the region,established its genetic model,Early due to strong regional compressive stress caused by the formation fold,forming a series of faults and fissures and fracture,Driven by gravity and concentration,Infiltration of surface water and groundwater along the fissure and fracture extraction Pb,Zn and other metals from the formation that containing Sedimentary Pb,Zn and other metals,therefore,the formation of hot brine.After favorable to the formation of carbonate,the hot brine altered wall rock and forming dolomitization,At the same time,dissolution of carbonate rocks formed karst cave,hole,etc.The hot brine enrichment precipitation in the favorable spatial include caves,intergranular porosity and fault fracture zone,etc.With the evolution of the fluid migration,the formation of calcatization,dolomitizat-ion,calcitization alteration zoning and massive ore,vein,patchy ore zonation from the from the center of ore bodies outwards.Later stage the fault activation formed breccia ores,resulting in breccia ores belt in the center.Thereby forming mechanism that fluid penetration-formation extraction-Ore controlling structure.?6?Combined with the actual geological conditions and foregoing understanding,proposed three concealed ore prospecting target area,Among them,the prediction target in the mining area of dajie has been validated.Added exploration eligible Pb-Zn metal reserves 50,000 tons and the ore grade:Pb 2%?10%,Zn 4%?30%.Currently,Liangyan Pb-Zn mining area has accumulated reserves over 100,000 tons,still has good exploration potential.