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Thermal conductivity changes in subducting basalt, Nankai subduction zone, SW Japan: An estimation from laboratory measurements under separate high-pressure and high-temperature conditions

By
Weiren Lin
Weiren Lin
Graduate School of Engineering, Kyoto University, Kyoto 615-8540, Japan, and Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Kochi 783-8502, Japan
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Osamu Tadai
Osamu Tadai
Marin Works Japan Ltd., Nankoku, Kochi 738-8502, Japan
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Masataka Kinoshita
Masataka Kinoshita
Earthquake Research Institute, The University of Tokyo, Tokyo 113-0032, Japan, and Research and Development Center for Ocean Drilling Science, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa 236-0001, Japan
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Jun Kameda
Jun Kameda
Department of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, Sapporo, Hokaido 060-0810, Japan
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Wataru Tanikawa
Wataru Tanikawa
Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Kochi 783-8502, Japan
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Takehiro Hirose
Takehiro Hirose
Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Kochi 783-8502, Japan
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Yohei Hamada
Yohei Hamada
Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Kochi 783-8502, Japan
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Osamu Matsubayashi
Osamu Matsubayashi
Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8567, Japan
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Published:
August 15, 2018
Publication history
25 September 201714 March 2018

ABSTRACT

Knowledge of rock thermal conductivity is necessary to understand the thermal structure in active seismogenic zones such as the Nankai Trough subduction zone, SW Japan. To estimate in situ thermal conductivity at the oceanic crust surface in the seismogenic zone, we measured the thermal conductivity of a basaltic basement core sample retrieved from subducting oceanic basement at the Nankai Trough Seismogenic Zone Experiment input site C0012 under high temperature (maximum 160 °C) and high pressure (maximum effective pressure 100 MPa), respectively. These conditions correspond to the in situ temperature and pressure at the oceanic crust surface in the updip limit of the Nankai seismogenic zone (~7 km below the seafloor). Thermal conductivity of the oceanic basalt is both temperature and pressure dependent. In contrast to other rock types such as sandstone and granite, for which thermal conductivity decreases with increasing temperature, the thermal conductivity of the oceanic basalt increased with increasing ambient temperature. The thermal conductivity of the basalt also increased with increasing effective pressure; however, the rate of increase was much lower than that for other rocks. These new temperature and pressure effect data for oceanic crust basalt fill a gap in the research. The estimated thermal conductivity of the basalt at in situ temperature and pressure conditions was less than ~2 W m–1 K–1, although deformation and alteration associated with subduction could decrease pore spaces in the basalt, leading to enhanced thermal conductivity. This value is significantly lower than that typically assumed for thermal structure simulations in the Nankai subduction zone.

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GSA Special Papers

Geology and Tectonics of Subduction Zones: A Tribute to Gaku Kimura

Timothy Byrne
Timothy Byrne
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Michael B. Underwood, III
Michael B. Underwood, III
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Donald Fisher
Donald Fisher
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Lisa McNeill
Lisa McNeill
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Demian Saffer
Demian Saffer
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Kohtaro Ujiie
Kohtaro Ujiie
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Asuka Yamaguchi
Asuka Yamaguchi
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Geological Society of America
Volume
534
ISBN electronic:
9780813795348
Publication date:
August 15, 2018

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