Inversion of magnetic and transient electromagnetic data for the characterization of skarn polymetallic mineralization in the Qimantagh Metallogenic Belt, China

Abstract

The growing demand for mineral resources in China underscores the critical importance of advanced exploration techniques. This study investigates the Yemaquan area within the polymetallic resource-rich Qimantagh Metallogenic Belt (QMB), using an integrated approach that combines total magnetic intensity (TMI) and grounded-wire short-offset transient electromagnetic (SOTEM) data to identify potential skarn-hosted mineralization. A 3D inversion of magnetic data revealed distinct subsurface zones with varying magnetic susceptibilities (0.01–0.18SI) at depths ranging from 25 to 350 m, indicating potential iron-rich accumulations. A quasi-2D inversion of SOTEM data, focused on a magnetically promising location, revealed a conductive zone (∼10 Ωm), indicating skarn alteration along the contact between a granodiorite intrusion and carbonate rocks. The integration of the inverted magnetic and SOTEM models facilitated the classification of the subsurface into seven distinct geological and mineralization units. Notably, the interpreted skarn zone (R5) was spatially related to two mineralization styles: Pb–Zn (R6) at depths of 50–150 m and Fe–Cu (R7) at a depth of 350 m. These findings were supported by mining drillholes in the area. This study demonstrates the efficacy of combining magnetic and electromagnetic geophysical methods for targeted mineral exploration in complex geological terrains, providing critical information for resource assessment and development in the QMB.