Application of shallow drilling geochemical survey to shallow overburden area at the peripheral of Nanjinshan gold mine in Beishan, Gansu Province

The Nanjinshan gold deposit is a typical epithermal deposit in Beishan metallogenic belt, which extends in a N-E direction to the peripheral shallow cover zone. In order to further achieve the breakthrough of prospecting in the peripheral shallow overburden area, the pilot work of motorized shallow drilling geochemical survey carried out. Based on the nature and thickness of the overburden, 126 motorized shallow drilling geochemical exploration samples are taken in the shallow overburden area using the vehicle mounted air positive circulation and three wing alloy scraper drilling or pneumatic DTH hammer drilling technology, with a sampling density of 16.8 points per square kilometer. The shallow drilling geochemical exploration methods and technologies in the shallow overburden area are further discussed, including the selection of drilling technology, sampling network, sampling materials, sample collection, etc. Soil survey was carried out in sporadic bedrock areas, and 278 samples were collected, and the sampling density was 48.77 points per square kilometer. Fifteen elements including Au, Ag, as, Sb, Hg, Cu, Pb, Zn, W, Sn, Mo, Bi, Cr, Co and Ni were analyzed. Through the above work, seven comprehensive geochemical anomalies were delineated. After anomaly investigation, six gold deposit bodies and one silver deposit body were found in the new circle in the bedrock area, and two concealed gold deposits and one silver deposit body were found in the shallow overburden area. The results show that shallow drilling geochemical survey is effective and feasible in the shallow overburden area of arid Gobi landscape in Beishan.