激发极化法在西藏昂青银多金属矿勘查中的应用

Application of the induced polarization method in exploration of the Angqing silver polymetallic deposit in Tibet

西藏昂青银多金属矿床为大型矽卡岩型银、铅、锌、铜多金属硫化物矿床,矿体赋存于中—下三叠统马拉松多组第一岩性段矽卡岩、大理岩地层中,矿化有黄铁矿化、方铅矿化、闪锌矿化和黄铜矿化等。运用激电中梯扫面方法,在矿区圈出JD1和JD2两个低阻高极化激电异常,JD1异常长1500 m,宽700 m,视极化率η_s:6.03%～14.2%,视电阻率ρ_s:22. 1～197 n·m,;JD2异常长900 m,宽500 m,视极化率η_s:6.04%～9.70%,视电阻率ρ_s:100～494Ω·m。两异常经钻孔验证,均见到隐伏银—铅—锌—铜多金属矿体,累计见矿30条。运用激电测深推测矿化体顶板埋深,钻孔验证基本相符。研究结果表明,激发极化法在昂青银多金属矿床勘查中有良好的应用效果。

The Angqing silver polymetallic deposit (ASPD) is a large skarnized polymetallic sulfide deposit, that was mainly hosted in the skarn and marble of the first member of Lower-Middle Triassic Malasongduo formation, its main ores are pyrite,galena, sphalerite, chalcopyrite and so on. The JD1 and JD2 induced polarization (IP) abnormities, that are low resistance and high polarization, were delimited by the method of IP. Length and width of the JD1 is 1500m and 700m, its apparent chargeability(ηs) is between 6.03-14.2% and the apparent resistivity(ρs) is between 22.1-197Ω.m. Length and width of the JD2 is 900m and 500m, its apparent chargeability(ηs) is between 6.04-9.7% and the apparent resistivity(ρs) is between 100-494Ω.m. The 30 hidden Ag-Pb-Zn-Cu orebodies were discovered after IP abnormity verification. Embedded depth of infered orebodies by IP sounding is close to that of the orebodies in hole. The research results show that the IP method is an effective approach for the hidden orebody exploration in ASPD,Tibet.