S-wave velocity structure beneath the eastern part of the Qinhang metallogenic belt and its adjacent areas

To further understand the structure of the Qinhang Metallogenic Belt (QHMB) and its adjacent areas in the southeastern region of China, we collected continuous waveform data from 73 broadband stations recorded from 1th January to December 31th 2021, and applied ambient noise tomography method to obtain the 3D S-wave velocity structure from the surface to the depths of 45 km in the area. We used the time–frequency normalization (FTAN) approach to extract 2035 phase velocity dispersion curves, and applied the Occam inversion algorithm to generate the phase velocity maps of 5 ~ 45 s. After that, we utilized the surf96 program to invert the 1D velocity structure of the S-wave under each grid, and then combined these grid points to produce a high-resolution 3D structure of the S-wave velocity structure. Based on the inversion results, we draw the conclusions as follows: (1) The high-speed body appearing in the middle crust below the Qinling Dabie Orogenic Belt (QDOB) may be the consequence of the direct cooling of partially melted magma formed by the upwelling of asthenosphere material into the middle and lower crust; (2) Since the Late Mesozoic, the subsidence of the lower crust and large-scale basal magma intrusion have caused a northeast-southwest trending high-speed band-shaped anomaly in the middle-lower crust of the area; (3) Against the background of continental extension, the thickening and extension of the crust have led to the enrichment of mineral-rich upwelling in suitable locations, ultimately forming the present-day metallogenic belts in the Middle-Lower Yangtze River Metallogenic Belt (MLYMB) and the eastern of the QHMB.