Application of multi-component gas geochemical survey for deep mineral exploration in covered areas

Abstract

There are many types of coverage areas in China, which are widely distributed and have huge resource potential. The overburden materials (vegetation, slope deposit, sedimentary rock, volcanic rocks, etc.) in coverage areas have introduced great difficulties and challenges to mineral exploration. In this contribution, a Portable Multi-component Gas Rapid Analyzer (PMGRA) was developed, a new instrument characterized by fast analysis, high precision, low cost, and easy portability. It can simultaneously detect a variety of mineralization-related gases (H2S, SO2, CH4, and CO2). Using PMGRA, accurate soil-gas geochemical survey was conducted in the Weilasituo Sn polymetallic deposit and Zhugongtang PbZn deposit. These hydrothermal deposits are dominated by faults and ores abundant in sulfide. The experimental results showed that PMGRA can detect accurate gas concentration data in the sediments of two covered areas. Above the deep-buried ore bodies, H2S, SO2, CH4, and CO2 gases had strong anomalies, and there was obviously strong gas anomaly in the upper part of the fault. It indicated that the gas geochemical measurement method using the gas rapid analyzer can reveal effective information about deep-buried ore bodies and faults. In the upper plate area of the fault, the peak of CO2 usually appeared before the peaks the H2S, SO2, and CH4, which could be used to predict the trend of the fault. The experiment also showed that the method can detect the mineralization information at 500 m and 800 m in the Weilasituo tin polymetallic deposit and the Zhugongtang PbZn deposit, indicating that the method has large detection depth. Therefore, the gas geochemical survey based on PMGRA is an effective working method suitable for mineral exploration in covered areas, which can provide a new idea for prospecting concealed ores in covered areas.