Abstract:

          Because  the  interpretation of seismic data  is not unique, seismic properties of  typical rock samples  from Jiangxi and
Fujian Provinces were studied  to better explain seismic data  in South China  in  terms of  the crustal structure and composition.
The P- and S-wave velocities of 5 rock samples were measured using MTS-815 Rock and Concrete Mechanics Test System. The
results indicate that seismic velocities of the samples increase with increasing pressure, but decrease with increasing temperature.
At  the  same pressure and  room  temperature,  the P- and S-wave velocities gradually decrease  from marbleized  limestones,
through granodiorites, K-feldspar granites  to siltstones. Because  the highest confining pressure  in  the experiments  is 140 MPa,
the measured velocities are only comparable with seismic observations  in  the upper crust. To constrain  interpretation of seismic
data at greater depths, we calculated  the seismic velocities of 39 samples based on modal compositions, elastic constants of
minerals and generalized mixing rules. The Vp/Vs and Poisson,s ratios of the samples increase with decreasing contents of quartz.
Compared with felsic rocks, the limestones, dolomites and marbles are characterized by high P-wave velocities, and high Vp/VS
and poisson,s ratios, which provides a way to search carbonate basins beneath the granite regions in South China.

Key words:  seismic velocities, Poisson^,s ratio, granite, limestone, South China