Depth of oceanic-crust underplating in a subduction zone: Inferences from fluid-inclusion analyses of crack-seal veins

Abstract

Research Article| November 01, 2003 Depth of oceanic-crust underplating in a subduction zone: Inferences from fluid-inclusion analyses of crack-seal veins M. Matsumura; M. Matsumura 1Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan Search for other works by this author on: GSW Google Scholar Y. Hashimoto; Y. Hashimoto 2Department of Natural Environmental Science, Kochi University, Kochi 780-8520, Japan Search for other works by this author on: GSW Google Scholar G. Kimura; G. Kimura 3Institute of Frontier Research for Earth Evolution, Japan Marine Science and Technology Center, Yokosuka 237-0061, Japan, and Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan Search for other works by this author on: GSW Google Scholar K. Ohmori-Ikehara; K. Ohmori-Ikehara 4Department of Natural Environmental Science, Kochi University, Kochi 780-8520, Japan Search for other works by this author on: GSW Google Scholar M. Enjohji; M. Enjohji 5Department of Earth Science, Waseda University, Tokyo 169-8555, Japan Search for other works by this author on: GSW Google Scholar E. Ikesawa E. Ikesawa 6Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information M. Matsumura 1Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan Y. Hashimoto 2Department of Natural Environmental Science, Kochi University, Kochi 780-8520, Japan G. Kimura 3Institute of Frontier Research for Earth Evolution, Japan Marine Science and Technology Center, Yokosuka 237-0061, Japan, and Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan K. Ohmori-Ikehara 4Department of Natural Environmental Science, Kochi University, Kochi 780-8520, Japan M. Enjohji 5Department of Earth Science, Waseda University, Tokyo 169-8555, Japan E. Ikesawa 6Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan Publisher: Geological Society of America Received: 09 Jun 2003 Revision Received: 05 Aug 2003 Accepted: 06 Aug 2003 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2003) 31 (11): 1005–1008. https://doi.org/10.1130/G19885.1 Article history Received: 09 Jun 2003 Revision Received: 05 Aug 2003 Accepted: 06 Aug 2003 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation M. Matsumura, Y. Hashimoto, G. Kimura, K. Ohmori-Ikehara, M. Enjohji, E. Ikesawa; Depth of oceanic-crust underplating in a subduction zone: Inferences from fluid-inclusion analyses of crack-seal veins. Geology 2003;; 31 (11): 1005–1008. doi: https://doi.org/10.1130/G19885.1 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 Fluid inclusions in crack-seal veins are analyzed in accreted mélange now on land. The vein I inclusions are observed in the necked parts of sandstone blocks in mélange, and the vein II inclusions developed in shale below the thrust fault, which cuts the mélanges. The pressure and temperature estimations from the inclusions within vein I show that the cracks were sealed at ∼125–195 °C under ∼92–144 MPa of fluid pressure. Vein II formed in cracks that might have opened in a damage zone caused by the thrust fault as it broke through oceanic crust and into the mélange; these veins contain fluid inclusions trapped at ∼135–245 °C under ∼107–149 MPa of fluid pressure. The depth (∼4–6 km below the seafloor) and temperature estimates are consistent with the conditions where an aseismic décollement within sedimentary rocks steps down into the oceanic basement, so that a thin section of oceanic crust underplates in the hanging wall. Such a step-down site is the updip limit of the seismogenic zone in the modern Nankai Trough. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.