Interpretation of 3D seismic reflection data in the Chinese Continental Scientific Drilling site

Seismic reflection investigations have been carried out for the Chinese Continental Scientific Drilling Project (CCSDP), showing that many reflectors occurred in the upper crust of the drilling area. Calibration of the reflectors by using cores, well-logging and VSP data can significantly enhance reliability of their interpretation. In the CCSD site, thickness of the ultrahigh-pressure (UHP) rock-slice is usually less than 10 km, beneath the UHP slice velocities of the middle and lower crust are normal among usual extensional areas. Ached the seismic reflectors in the 3D seismic main line are caused by the high-velocity eclogite bodies plus low-velocity fractures; strong dipping reflectors are caused the ductile shear rock-suites that consist of. mylonite and interbed of thin eclogites and gneiss. The 3D survey provides 3D reflection wave-field that can be shown by time-slice sets.. Time slices above 450ms are intensively correlated with surface geology and magnetic anomalies, whilst slices of 1000 similar to 1200ms correlate with the gravity anomalies, indicating buried eclogite bodies. Based on the interpretation a structural section across the CCSD main hole is presented.