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Title: Thermal conductivity profilein the Nankaiaccretionary prism at IODP NanTroSEIZE Site C0002: estimationsfromhigh-pressure experiments using input site sediments
Authors: Lin, Weiren
Hirose, Takehiro
Tadai, Osamu
Tanikawa, Wataru
Ishitsuka, Kazuya  kyouindb  KAKEN_id  orcid (unconfirmed)
Yang, Xiaoqiu
Author's alias: 林, 為人
Keywords: thermal conductivity
high pressure experiments
Nankai Trough
accretionary prism
Issue Date: Jul-2020
Publisher: American Geophysical Union (AGU)
Journal title: Geochemistry, Geophysics, Geosystems
Volume: 21
Issue: 7
Thesis number: e2020GC009108
Abstract: Depth profiles of sediment thermal conductivity are required for understanding the thermal structure in active seismogenic zones. During the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a scientific drilling project of the International Ocean Discovery Program (IODP), a borehole was penetrated to a depth of 3, 262.5 m below seafloor (mbsf) at Site C0002. Because core samples obtained from below ~1, 100 mbsf in an accretionary prism are limited, a thermal conductivity profile over such depths usually determined by laboratory measurements using core samples is not available. To obtain the thermal conductivity profile at Site C0002, we used core samples collected from sediments that overlay the incoming subducting oceanic basement at Nankai Trough Seismogenic Zone Experiment Site C0012, which can be considered to have the same mineral composition as the accretional prism at Site C0002. The thermal conductivity of the C0012 core samples was measured at high pressure to simulate subduction by reducing the sample porosity. We measured the thermal conductivity of six core samples from 144–518 mbsf at Site C0012 up to a maximum effective pressure of ~50 MPa, corresponding to depths greater than ~4 km below seafloor. We obtained an empirical relation between thermal conductivity λBulk in Wm⁻¹K⁻¹ and fractional porosity ϕ for the Nankai Trough accretionary prism as λBulk = exp(−1.09ϕ + 0.977). Based on porosity data measured using core/cuttings samples and data derived from P wave velocity logs, we estimate two consistent and complete thermal conductivity profiles down to ~3 km below seafloor in the Nankai Trough accretionary prism. These profiles are consistent with the existing thermal conductivity data measured using limited core samples.
Rights: ©2020. American Geophysical Union. All Rights Reserved.
The full-text file will be made open to the public on 21 January 2021 in accordance with publisher's 'Terms and Conditions for Self-Archiving'.
DOI(Published Version): 10.1029/2020GC009108
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