Seismic pumping for mineralizaiton in southern Fujian, Cathaysia Block: New insights from a teleseismic full waveform inversion


It is crucial to image the crustal velocity structure with higher resolution to understand the relationship between crustal seismicity and metallogenic mechanisms, which remain challenging targets for conventional seismic tomography. Teleseismic tomography via body-waves can image velocity well in the upper mantle, but poorly in the crust. In this study, we have developed a teleseismic full waveform inversion (TFWI) method based on the frequency-wavenumber spectral element method (FK-SEM) hybrid to improve the resolution of teleseismic P-waves in the crust. We used the TFWI method to study the crustal velocity by using two large teleseismic events recorded by 29 portable stations with ~5 km intervals across the Zhenghe-Dapu Fault (ZDF) in the Cathaysia Block. This is the first attempt using the FK-SEM hybrid on real data. As expected, we obtained a 2D velocity model in the crust that had high lateral resolution. There is an obvious low velocity zone (LVZ) in the crust below east side of the ZDF, while a relatively high velocity anomaly exits within its west side. Combined with previous geochemical and geological results, this LVZ is explained as remnant magma due to the large-scale magmatism in the Late Jurassic and Early Cretaceous. According to the spatial correlation among the LVZ, local earthquakes, faulting, and major ore deposits, we consider that seismic pumping might be a mechanism of thermal fluid transport for the mineralization.

Ore Geology Reviews