| The Zhaxikang lead-zinc polymetallic deposit is located at the eastpart of Tethys Himalaya gold-antimony metallogenic belt.After many years of geological exploration,it has now become a large-scale ore deposit.However,this deposit is facing a dilemma of increasing mining degree with limited reserves.It thus urgently needs the guidance of basic theories and systematic study on metallogenetic laws,carrying out works and delineating new prospecting targets in the areas with low exploration degree and great mineralization potential.In this study,the Zhaxikang lead-zinc polymetallic deposit is selected forresearch.On the basis of field work and previous studies,we systematically summarize the geological characteristics and prospecting criteria,and interpret remote sensing images,and delineate geochemical element-combination anomalies,inverse geophysical data and delineate mineralization prospect areas using similar analogy methods.In the deposit area,the early-middle Jurassic Lure group,upper Jurassic Weimei group,and upper Jurassic-lower Cretaceous Sangxiu group are exposed.There is rhyolite,dacite,diorite,diabase and granite porphyry in the mining area.The orebodies are controlled by NS-trending faults,and ore types mainly include massive,brecciated,banded and disseminated structures.The wall rockalteration schiefly have silicification,limonitization,pyritization,cabonatization,kaolinization,chloritization,sericitization.Faults,gossan,lithology,rockalteration and geophysical characteristicsare main prospecting marks.Based on the petrographic studies and previous research,we preliminarily propose that the Zhaxikang Pb-Zn polymetallic deposit was of hydrothermal origin,which had multiple periods and stages,and subsequently underwent multistage structural deformation.Four groups of NS,NWW,NE and nearly EW-trending faults are illuminated by remote sensing images in the deposit area.Geochemical analyses still show Pb,Zn,Sb,Ag and Au element assemblage anomalies associated with medium-low temperature hydrothermal mineralization in the Zhaxikang deposit.These closely coupling anomalies are large-scale with significantly high intensity and apparent concentration center,and they are most likely related to post magmatic hydrothermal mineralization.The regional geophysical features are characterized by Bouguer anomalies and intensive gravity gradients,showing an affinity with the well-developed faults and complicated geological structures.The seven aeromagnetic anomalies are probably caused by rock masses and altered rocks.Four concealed intermediate to acidic rock masses are located at the intersection positions of faults according to our aeromagnetic data,where are conducive to magmatic intrusion;one rock mass situates in the deep of the Zhaxikang deposit area.On the basis of our field investigations,including ore-controlling factors,mineralization and alteration,F24,F23,F17 fracture zones and the southern areas of ? orebody with obvious mineralization alteration are identified.High precision remote sensing information identify four insidious faults that are undiscovered in the past,providing remote sensing basis for the prospecting prediction.After repeatedly geophysical prospecting tests on the known ? orebody,the AMT audio-frequency magnetotellurics and large power induced polarization sounding methods are ultimately adopted,showing that the ore-bearing fractures have medium to high polarization ratios and resistivities.Then,interpreting and inferring geophysical information in blank areas,two abnormal areas are found.It provide geophysical basis for the prospecting prediction.After comprehensive consideration onore-controlling rules,high-resolution remote sensing interpretation and geophysical information,the integrated information exploring model is created.A total of four prospecting targets are delineated.Drilling project attestation on the ? prospecting targets,in the south of 40 prospecting line of ?,?,?? ore bodies,gained good effects and exhibited a nice future for the further exploration. |
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