Study Of Velocity Structure Of Jiama-Qulong From Ambient Noise On Tomography

The Jiama-Qulong mineralized area is a typical "porphyry-silica" mine in the eastern section of the Tibetan Gangdis,which has a strong magmatic activity that provides necessary conditions for later mineralization.The previous research on the mineralization of the mine area is late,thus the research on the genesis of the deposit only stays in the shallow layer.we need to investigate the mineralization mechanism of the Jiama-Qulong based on the previous studies,to solve the problem of geological mineralization conditions and deep tectonics of the mine area.The detection technique is base on a passive source short-period dense stage array.The high-resolution three-dimensional S-wave velocity structure was established in and around the mine area by the background noise imaging method to identify the fugacity state of magmatic ore bodies and magmatic rock channels at the bottom of the lithosphere.We deployed 232 short-period dense mobile observation arrays within an area of about60 km centered on the Jiama-Qulong mine from September to October 2019 and carried out continuous recorded observations for one month.The collected waveform data were subject to single-station preprocessing,band-pass filtering,mutual correlation function calculation,and weighted superposition to recover the empirical Green's function of Rayleigh waves in the study area for periods of 2-8s.After that,the group velocity dispersion curves of 2?8s period get the fast dispersion extraction method of multiple filtering.Finally,the S-wave horizontal velocity structure in the 9 km depth range is get by the direct inversion method based on "ray tracing".The S-wave velocity constraint by dense stage array noise imaging technique can well reflect the geological features of Jiama-Qulong mine and adjacent areas.The cross-sections at different depths depict the spatial distribution of stratigraphy and rock masses under the mine area,thus providing a preliminary reflection of the mine structure.The low-velocity body structure at the Jiama-Qulong mine area at a shallow depth of 7 km shows that there is a common "magma house" exposed there,which proves the origin and evolution of porphyry copper ores in the ore-bearing magma.It provides a favorable basis for studying the magmatic system in the deep part of the Gondwana mineralization zone and helps to expand the prospect of increasing reserves in this large mineral resource base.