Deep Structure of Nanling-Xuancheng Ore District, Eastern China: Insights from Integrated Geophysical Exploration

Abstract

As the depth of mineral exploration increases, integrated geophysical methods are increasingly playing a crucial role in prospecting deep structures at the district scale. The Nanling-Xuancheng ore district is the eighth ore district in the middle-lower Yangtze metallogenic belt in China. To reveal the deep structure of the mining district, this study mainly focuses on regional high-precision gravity and magnetic data and integrates the interpretation of magnetotelluric and reflection seismic data from a key area. By using a 2.5D joint inversion method with prior information constraints, new insights into the deep structures, tectonic deformation, and magmatic activity are obtained. Structurally, the Nanling-Xuancheng ore district presents a structural pattern of “two uplifts and two depressions” composed of multi-level thrust-overturned and folds formed by Mesozoic depressions, which has a three-layer structure in the vertical direction (shallower than 10 km). Tectonically, the main faults in the study area trend NW, which intersect with NE-trending and EW-trending faults to form a branching structure from deep to shallow. The fault intersections provide pathways for magma intrusion. The distribution of deep-seated concealed magmatic rocks shows the characteristic pattern of “a primary magma source spawning multiple subsidiary intrusion”.