Velocity structure heterogeneity and tectonic motion in and around the Tan–Lu fault of China

The depth distribution of the Moho discontinuity and the P-wave velocity structure in and around the Tan–Lu fault were analyzed employing data from seismic reflection and refraction sounding from greater than 40 profiles. The results suggest that high P-wave velocity zones have emerged in the upper crust of the Dabie and Sulu ultrahigh pressure metamorphic (UHPM) belts. Anomalous zones of low velocity in the lower crust and the deep Moho discontinuities imply that the low crustal velocity structure zones exit in the Dabie and Sulu region. The high-velocity anomalous zones in the upper crust and low-velocity anomalous zones in the lower crust beneath the Sulu region are all located northeast of the northern segment of the Tan–Lu fault. The high- and low-velocity anomalous zones beneath the Dabie region are located southwest of the southern segment of the Tan–Lu fault. Such a distribution pattern of the velocity-anomalous zones may show some evidence of the left strike-slip motion regime of the Tan–Lu fault. The low velocity structure in the crust emerged beneath the joining region between the Dabie and Sulu orogens near the Tan–Lu (T–L) fault.

► High- and low-velocity zones are in the upper and lower crust of Dabie and Sulu belt.
► The Moho discontinuities deepen beneath Dabie and Sulu UHPM belts.
► High- and low-velocity zones beneath the Sulu are northeast of the Tan–Lu fault.
► High- and low-velocity zones beneath the Dabie are southwest of the Tan–Lu fault.
► Distribution of velocity zones show the left strike-slip regime of the Tan–Lu fault.