Identifying mineral prospectivity using seismic and potential field data in the Hongniangyu district, Inner Mongolia, China

Abstract

Since the discovery of several large porphyry Mo deposits (>0.1 Mt Mo) in the Jining region of Inner Mongolia, China, during the past decades, the area has been receiving wide interest for mining activities. However, mineral exploration in this area is challenging because most of it is thickly covered by Cenozoic sediments. Geophysical surveys, especially the seismic method, are becoming increasingly important for investigating deep-seated ore-controlling structures (e.g., porphyry granites, faults and even orebodies), supporting the discovery of buried ore deposits. Recently, potential field data and seismic reflection data have been acquired for the Hongniangyu area, south of Jining region. In this study, we mainly use seismic reflection and potential field data to obtain subsurface geological model in support of mineral exploration targeting. Gravity and magnetic data were firstly used for spatial analysis of mineral system by mapping the distribution of the faults, concealed granites, and the sedimentary basin (through wavelet analysis, tilt angle, and Euler deconvolution). To address the common problem of low signal-to-noise ratio of seismic reflection data obtained in hard-rock terranes, we applied a sophisticated workflow including refraction static correction, noise filtering, surface-consistent deconvolution, and velocity analysis. The obtained post-stack migrated seismic profile clearly imaged the geometry of the concealed graben located at the north end of the Datong Basin, and the South-East dipping Kouquan normal fault controls the depression of the graben and offsets Cenozoic sediments by several hectometers up to ~500 m. Joint modeling of seismic, gravity and magnetic data further provided evidence of the three buried belts of granites. Intriguingly, one of the concealed granitic belts located in the north of Hongniangyu area was found to have both significant chargeability and Mo geochemical anomalies, indicating a high potential of hosting porphyry-type Mo ore deposits. As expected, Mo and W mineralized cores were discovered in this target area but limited to only one deep drilling hole. The presented results provide the geological framework of Hongniangyu district and guidelines for delineating new potential Mo mineralization in the Jining region.