A 3D Investigation of Geological Structure and Its Relationship to Mineralization in the Nanling-Xuancheng Ore District, Middle-Lower Yangtze River Metallogenic Belt, China

摘要

The Nanling-Xuancheng ore region of Anhui Province is located in the Middle-Lower Yangtze River metallogenic belt. Insufficient exploration and research have been carried out in this newly defined ore district, although the Chating large porphyry Cu-Au deposit and a few middle-sized skarn-type Cu polymetallic deposits have been discovered. In this study, we carried out high-resolution seismic reflection, magnetotelluric, gravity, and magnetic investigations, and constructed the 3D geological structure of the uppermost crust in a depth range of 0-5 km using a comprehensive inversion of the new data constrained by previous deep-drilling data. We hence proposed some new insights to understand the mineralization processes of this district. A system of alternating ridges and valleys is suggested as the major structure pattern, composed of "two-layer structure" of the basins and "three-layer structure" of anticlines. Moreover, a conjugated fault system and its distribution features are revealed in our models, including the Jiangnan fault, Zhouwang fault, and Kunshan thrust nappe. The Jiangnan and Kunshan faults are suggested to have controlled the diagenesis and metallogenesis. Two deep concealed plutons located in Chating and Magushan are found, forming the Mesozoic diorite-felsic intrusions. These intrusions are believed to be the causes of hydrothermal deposits such as the Chating deposit and the Magushan deposit.

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