P-wave velocity differences between surface-derived and core samples from the Sulu ultrahigh-pressure terrane: Implications for in situ velocities at great depths

Abstract

Research Article| July 01, 2012 P-wave velocity differences between surface-derived and core samples from the Sulu ultrahigh-pressure terrane: Implications for in situ velocities at great depths Shengsi Sun; Shengsi Sun 1Département des Génies Civil, Géologique et des Mines, École Polytechnique de Montréal, Montréal, Quebec H3C 3A7, Canada Search for other works by this author on: GSW Google Scholar Shaocheng Ji; Shaocheng Ji * 1Département des Génies Civil, Géologique et des Mines, École Polytechnique de Montréal, Montréal, Quebec H3C 3A7, Canada2State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China *E-mail: sji@polymtl.ca; wangqian@gig.ac.cn. Search for other works by this author on: GSW Google Scholar Qian Wang; Qian Wang * 3State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China *E-mail: sji@polymtl.ca; wangqian@gig.ac.cn. Search for other works by this author on: GSW Google Scholar Matthew Salisbury; Matthew Salisbury 4Geological Survey of Canada-Atlantic, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada Search for other works by this author on: GSW Google Scholar Hartmut Kern Hartmut Kern 5Institut für Geowissenschaften, Universität Kiel, Kiel 24098, Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Shengsi Sun 1Département des Génies Civil, Géologique et des Mines, École Polytechnique de Montréal, Montréal, Quebec H3C 3A7, Canada Shaocheng Ji * 1Département des Génies Civil, Géologique et des Mines, École Polytechnique de Montréal, Montréal, Quebec H3C 3A7, Canada2State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China Qian Wang * 3State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China Matthew Salisbury 4Geological Survey of Canada-Atlantic, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada Hartmut Kern 5Institut für Geowissenschaften, Universität Kiel, Kiel 24098, Germany *E-mail: sji@polymtl.ca; wangqian@gig.ac.cn. Publisher: Geological Society of America First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2012 Geological Society of America Geology (2012) 40 (7): 651–654. https://doi.org/10.1130/G33045.1 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Shengsi Sun, Shaocheng Ji, Qian Wang, Matthew Salisbury, Hartmut Kern; P-wave velocity differences between surface-derived and core samples from the Sulu ultrahigh-pressure terrane: Implications for in situ velocities at great depths. Geology 2012;; 40 (7): 651–654. doi: https://doi.org/10.1130/G33045.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We compared the averages of P-wave velocities (Vp) for four lithologies (felsic gneiss, eclogite, retrograde eclogite, and amphibolite) collected from core material sampled by the Chinese Continental Scientific Drilling Project (CCSD) at depths to 5158 m, and from surface outcrops in the Dabie-Sulu (China) ultrahigh-pressure metamorphic terrane. The velocities were measured at pressures to 800 MPa for 69 CCSD samples and 145 surface samples. The Vp-pressure relationship is described by a four-parameter exponential equation, allowing the determination of the crack-closing pressure (Pc), the intrinsic pressure derivative of velocity (D), the intrinsic velocity of the crack-free compacted rock at zero pressure (V0), and the maximum velocity increase due to crack closure (B0). The shape of the nonlinear segment of the velocity-pressure curve is controlled by a decay parameter (k). The CCSD core samples are characterized by significantly higher V0, B0, and k values and lower D and Pc compared to their surface analogues. This suggests that extrapolation of the surface rock data to depth may result in substantial underestimates in seismic velocities, and that the intrinsic pressure derivatives obtained from the Vp-pressure relations for the core samples are more suitable for the determination of in situ velocities at great depth than those derived from measurements on rocks exposed at the surface. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.