HR: 0800h
AN: V11A-1403    [Abstracts]
TI: Deformation Induced Anisotropy of Thermal Conductivity and Seismic Velocity in UHP Rocks From CCSD Main Hole
AU: * Ou, X
EM: xgou@gig.ac.cn
AF: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 China
AU: Jin, Z
AF: Department of Earth Sciences, China University of Geosciences, Wuhan, 430074 China
AU: Xia, B
AF: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 China
AU: Wang, L
AF: Department of Earth Sciences, China University of Geosciences, Wuhan, 430074 China
AB: Both thermal conductivity and seismic velocity of rocks are of great interests to geologists because they provide important constrains on interpretation of rock dynamics at depths. Numerous investigations have shown that there is a strong correlation between seismic anisotropy and deformation in rocks. In principle deformation should have similar impact on thermal conductivity anisotropy. We present here preliminary results from thermal conductivity and seismic velocity measurements at atmospheric pressure and room temperature on drill cores from the Chinese Continental Scientific Drilling (CCSD) main hole located at Donghai County, eastern China. We measured thermal conductivity and seismic velocity of about 300 mini core samples including eclogites, gneisses and serpentinized garnet peridotites. A half-space line needle probe with transient heat flow method was applied to determine the anisotropy of thermal conductivity. The investigation gives information that thermal conductivity varies with lithology, mineral assemblage, even the degree of retrogression, but the most important influence factor is directional dependence, that is, to the same rock sample, both the thermal conductivity and the seismic velocity vary significantly with the azimuth of the measurement relative to the foliation if it developed in UHP rocks. The thermal conductivity parallel to the foliation can be up to 24% larger than that normal to the foliation while the P-wave velocity parallel to the foliation is 14% faster in average than that perpendicular to the foliation. Though there is no obvious correlation between the thermal conductivity and the seismic velocity in these rocks, the thermal conductivity anisotropy increases approximate linearly with the seismic anisotropy with a correlation coefficient of 0.91. Our results suggest that deformation controls not only the seismic anisotropy but also the thermal conductivity anisotropy in UHP rocks. It is necessary to investigate into the corresponding mineral fabrics for a better understanding of rock anisotropy.
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 5754 Physical properties of materials
DE: 6045 Physics and chemistry of materials
DE: 1744 Tectonophysics
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting