Knowledge of seismic velocities is necessary to constrain the lithologies encountered in seismic studies. We measured the seismic velocities, both compressional and shear wave, of clasts recovered during Ocean Drilling Program Leg 195 from a serpentine mud volcano, the South Chamorro Seamount. The compressional wave velocities of these clasts vary from a lower value of 5.5 km/s to an upper value of 6.1 km/s at a confining stress of 200 MPa. The shear wave velocities vary from a lower value of 2.8 km/s to an upper value of 3.3 km/s at a confining stress of 200 MPa. The densities of the samples vary from 2548 to 2701 kg/m3. These velocities and densities are representative of the highly serpentinized harzburgite and dunite mineralogy of the clasts. Velocities from a seismic study of the Izu-Bonin forearc wedge were used to calculate the degree of serpentinization in the forearc wedge. The seismic velocities of the forearc wedge are higher than the velocities of the clasts recovered from the South Chamorro Seamount, suggesting that the clasts are more serpentinized than the forearc wedge.
1 Courtier, A.M., Hart, D.J., and Christensen, N.I., 2004. Seismic properties of Leg 195 serpentinites and their geophysical implications. In Shinohara, M., Salisbury, M.H., and Richter, C. (Eds.), Proc. ODP, Sci. Results, 195 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/195_SR/104/104.htm>. [Cited YYYY-MM-DD]
2 Department of Geology and Geophysics, University of Wisconsin, 1215 West Dayton Street, Madison WI 53706, USA.
3 Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive Southeast, Minneapolis MN 55455, USA.
4 Wisconsin Geological and Natural History Survey, 3817 Mineral Point Road, Madison WI 53705, USA. djhart@wisc.edu
Initial receipt: 5 January 2004
Acceptance: 30 July 2004
Web publication:
26 October 2004
Ms 195SR-104