An array based seismic image on the Dahutang deposit, South China: Insight into the mineralization

Abstract

As a world-class W–Cu–Mo polymetallic deposit in South China, there are lots of studies focusing on the geochemical characteristics and metallogeny in this region, however, geophysical observations with special attention on the deep structure of the ore district are quite few. In order to better understand the metallogenic mechanism at Dahutang region, we deployed a dense seismic array and then performed the seismic image to get the deep structure, including the ambient noise tomography, receiver function calculation, H-κ stacking and joint inversion of receiver function and surface wave dispersion. The Moho depth deepens from the south to the north along the array. The seismic image and gravity anomaly show a low velocity in the upper crust, high velocity in the middle-lower crust, relatively high Vp/Vs ratio, and low gravity anomaly beneath the Dahutang deposit. These features may indicate the process of mineralization: under the context of lithospheric extension and thinning in the Late Mesozoic, there are some magma underplating and melting the lower crust. The hot melts migrated upward and differentiated, the dense component cooled in the middle-lower crust to form the high velocity zones. The light component intruded into the Neoproterozoic granite and formed the Mesozoic granite, providing the heat and material source for the further enrichment of tungsten‑copper polymetallic ore.