Integrated geophysical exploration of the coupling of a concealed rock body and metallogenic structures—Ag-Pb-Zn mining area case study in Jilinbaolige, Inner Mongolia, China

Abstract The Jilinbaolige polymetallic deposit, located in the Dong Ujimqin Banner in Inner Mongolia, China, belongs to the Daxinganling and Nangebi-Dongwu Banner polymetallic metallogenic belts. In recent years, many medium to large Ag-Pb-Zn deposits have been discovered, but due to their deep burial and the Quaternary soils cover, mineral exploration is difficult. In order to investigate the relationship among the mineralization, rock body and tectonic structures in the study region, we implemented 5.57 km2 magnetic exploration and four audio-magnetotelluric survey lines with 184 exploration points. Through comprehensive geophysical and geological inference and interpretation, we identified two types of granite which were formed at different stages in the early Yanshanian period, and inferred the NNE F4, NW F5 and NW F6 faults as the ore-conducting and ore-hosting structures of the Ag-Pb-Zn deposits. We determined that the faults' intersections provide the main metallogenic spaces while also locating concealed rock bodies interspersed as small stocks or veins within the upper Devonian Anguinwula formation. Apparently the Ag-Pb-Zn deposits are closely related to subsequently intrusive monzonitic granites of the early Yanshanian period. As confirmed by drilling, many Ag-Pb-Zn ore veins are found at 550–600 m depths and monzonitic granite porphyries at 750 m depth. Our geophysical exploration results reveal the coupling relationship between the concealed rock bodies and metallogenic structures, which can provide direction and effective geophysical methods to prospect for potentially similar deposits in the surrounding area.