摘要
The P-wave velocity structure in the shallow crust is investigated in and around the Sulu-Dabie region by using seismic reflection data for deep soundings in 48 survey profiles and from rock velocity determinations.The observed velocity distributions show obvious heterogeneities in this region.The low velocity anomalies are observed mainly in the west of the Dabie region and the East Sea regions.The high velocity anomalies emerge in the shallow crust of the Sulu and Dabie orogeny.These high-velocity anomalies can be attributed to the ultra-high pressure metamorphosed(UHPM)rock formed by exhumation motion of mantle materials during the orogeny.The high-velocity anomalies in the different shallow layers beneath the Sulu region are located to the northeast of the Tan-Lu fault.The high-velocity anomalies beneath the Dabie region are located southwest of the Tan-Lu fault.Such a distribution pattern of velocity anomaly zones may reveal historical motion of a left-lateral strike-slip for the Tan-Lu fault,which differs from the result of a right-lateral strike-slip motion regime known from modern seismology,indicating a more complex tectonic motion along the Tan-Lu fault.
基金
This study was supported financially by the Natural Science Foundation of China(Grant No.41374052)
the Science Foundation of China Geological Survey(No.J1901)
the project of Regional Geological Survey(No.D1911).
