The Deep Tectonic Features of Qitianling Ore-Concentrated Area in Southern Hunan Province and Its Contrains to the Regional Ore-Forming Processes

The Qitianling ore-contrated area in Southern Hunan province,one of the most important nonferrous metal bases in China with extensive fault structure,sufured multiperiod magmatic activity such as the intrusion of Qitianling granite,and produced many types of ore deposits with multi-mineral such as Huangshaping Pb-Zn deposit.In order to analyze the contrains of deep tectonic features to the ore-forming processes in Qitianling area,an artificial seismic profile crossing the Huangshaping deposit and Qitianling granite body was finished.The seismic data collected from 651physical points was stacked linearly,and the artifical earthquake was excitated through big shots combining with small shots.The reflection seismic profile showed that three obvious wave groups were existed in the upper,middle and deep part of Qitianling area,and Moho locates at the depth of 33~38km.In the depth of the Qitianling granitic intrusion,the seismic wave groups reflect that Moho is not continuous in the tectonic style of reverse fault and funnel,which is consistent with the distribution shape of seismic wave velocity.These features illustrated the exitence of an upwelling pathway for mantle material,which possible ascribed to the intrusion of granitic magma and the regional mineralization.The pathway can correspond to the ChalingChenzhou-Linwu deep faults,indicating that the participation of mantle material was one of the key factors for the large-scale mineralization in Qitianling area.The features of Moho suggested that strong squeezing action ever occurred in Mesozoic in Qitianling area,finally leading to the thickning of lithospheric mantle, and then the delamination and magma intrusion.In such process,mineralization material and energy were provided.