Seismic properties of eclogites: implications on crustal composition and exhumation mechanism of the Sulu ultrahigh-pressure metamorphic belt
榴辉岩的地震波性质：对苏鲁超高压变质带地壳成分和折返机制的探讨

Laboratory-derived P- and S-wave velocities for three types of eclogites are summarized. Combined with seismic properties of other lithologies, the results are helpful to interpret seismic data from the Dabie-Sulu orogenic belt. The interfaces between eclogites (high velocity and density) and almost all other lithologies such as felsic gneisses, marble, quartzite, amphibolite, mafic granulite, and serpentinized peridotite show large values of reflection coefficient ( >0. 1) and are thus able to produce strong seismic reflections. If crustal materials subducted and preserved in the lithospheric upper mantle as eclogites interlayered with felsic gneiss, garnet-jadeite quartzite, marble and serpentinized peridotite, they could be a good candidate for regional seismic reflections beneath orogenic belts, Based on a refraction profile in the Chinese Continental Scientific Drilling area, the crustal composition beneath the Sulu UHP belt is estimated to test different exhumation models of UHP rocks. Although eclogites are widely exposed in the surface and drill holes, they may not exit in the todays deep crust of the Sulu terrane, implying that these UHP rocks are tectonic slices that exhumed along a series of shear zones and finally thrust over an UHP-free middle-lower crust.