Multidisciplinary Geophysical Investigations over Deep Coal-Bearing Strata: A Case Study in Yangjiazhangzi, Northeast China

With the majority of coal mines in uncovered and semi-covered coal strata now explored and developed, most of the undiscovered coal-bearing strata are concealed. Compared with expensive drilling, deep targets such as concealed coal-bearing strata can be more efficiently and cost-effectively discovered through geophysical methods. We designed an integrated geophysical exploration approach to detect coal-bearing strata in the Yangjiazhangzi (YJZZ) area. Large-scale magnetotellurics (MT) is used to describe the geological structure along with its profile through the YJZZ area. An aeromagnetic survey was used to delineate the spatial distribution characteristics of the YJZZ syncline, a coal-bearing prospect tectonic unit. Localized exploration with controlled-source audio magnetotellurics (CSAMT) and MT reveals coal-bearing targets for drilling. Drilling results verified the targets identified through the integrated geophysical approach. Coal-bearing strata in the Benxi formation, the Taiyuan formation, and the Shanxi formation of the Permo-Carboniferous age are found between 630 and 770 m. This case study demonstrates that the multidisciplinary geophysical strategy can provide reliable results and credible data interpretation for deep coal seam resources exploration. The findings of this study can provide reference for explorers to carry out their specific exploration cases.