Lithofacies identification and deep structure of Tonghua area in the periphery of Songliao Basin based on high-precision gravity-magnetic electrical survey

Tonghua area is a new oil and gas exploration area in the periphery of eastern Songliao Basin and is characterized by low-grade degree oil and gas exploration. The key geological problems such as sedimentary stratigraphic distribution features and deep structure characteristics of the basin remain unknown. Gravity-magnetic-electrical exploration is an important method for revealing the deep structural features and structural framework of the basin. Based on several gravity-magnetic-electrical survey lines, the authors obtained the comprehensive interpretation of Tonghua area tectonic framework. There are 4 class-Ⅰ faults and 46 secondary faults in the Tonghua area, which control the basic tectonic framework in the study area. For the first time, five faulted basins were identified, namely Hongmiaozi, Huanren, Shajianzi, Guanmozi and Muqi basin. The scale of the basin, the maximum buried depth of the Mesozoic strata, the features of Houjiatun Formation and deep structural framework were determined in this study. In addition, the authors carried out the division of tectonic units in the Huanren Basin and the Guaimozi Basin. This study would provide important basic geological information for further oil and gas exploration, and also have great guiding significance for exploration and deployment in the new periphery areas of eastern Songliao Basin.