Progress in Earth and Planetary Science (Nov 2018)
In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough
- Yohei Hamada,
- Takehiro Hirose,
- Akira Ijiri,
- Yasuhiro Yamada,
- Yoshinori Sanada,
- Saneatsu Saito,
- Noriaki Sakurai,
- Takamitsu Sugihara,
- Takahiro Yokoyama,
- Tomokazu Saruhashi,
- Tatsuhiko Hoshino,
- Nana Kamiya,
- Stephen Bowden,
- Margaret Cramm,
- Susann Henkel,
- Kira Homola,
- Hiroyuki Imachi,
- Masanori Kaneko,
- Lorenzo Lagostina,
- Hayley Manners,
- Harry-Luke McClelland,
- Kyle Metcalfe,
- Natsumi Okutsu,
- Donald Pan,
- Maija Jocelyn Raudsepp,
- Justine Sauvage,
- Florence Schubotz,
- Arthur Spivack,
- Satoshi Tonai,
- Tina Treude,
- Man-Yin Tsang,
- Bernhard Viehweger,
- David T. Wang,
- Emily Whitaker,
- Yuzuru Yamamoto,
- Kiho Yang,
- Masataka Kinoshita,
- Lena Maeda,
- Yusuke Kubo,
- Yuki Morono,
- Fumio Inagaki,
- Verena B. Heuer
Affiliations
- Yohei Hamada
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Takehiro Hirose
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Akira Ijiri
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Yasuhiro Yamada
- Research and Development Center for Ocean Drilling Science, Japan Agency for Marine-Earth Science and Technology
- Yoshinori Sanada
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Saneatsu Saito
- Research and Development Center for Ocean Drilling Science, Japan Agency for Marine-Earth Science and Technology
- Noriaki Sakurai
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Takamitsu Sugihara
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Takahiro Yokoyama
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Tomokazu Saruhashi
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Tatsuhiko Hoshino
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Nana Kamiya
- Department of Urban Management, Graduate School of Engineering, Kyoto University
- Stephen Bowden
- Department of Geology and Petroleum Geology, School of Geosciences, University of Aberdeen
- Margaret Cramm
- Department of Biological Sciences, University of Calgary
- Susann Henkel
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
- Kira Homola
- Graduate School of Oceanography, University of Rhode Island
- Hiroyuki Imachi
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology
- Masanori Kaneko
- Geomicrobiology Research Group, National Institute of Advanced Industrial Science and Technology (AIST)
- Lorenzo Lagostina
- Department of Environmental Systems Science, ETH Zürich
- Hayley Manners
- School of Geography, Earth and Environmental Sciences, Faculty of Science and Engineering, Plymouth University
- Harry-Luke McClelland
- Department of Earth and Planetary Sciences, Washington University in St. Louis
- Kyle Metcalfe
- Division of Geological and Planetary Sciences, California Institute of Technology
- Natsumi Okutsu
- Atmosphere and Ocean Research Institute, The University of Tokyo
- Donald Pan
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology
- Maija Jocelyn Raudsepp
- School of Earth Sciences, University of Queensland
- Justine Sauvage
- Graduate School of Oceanography, University of Rhode Island
- Florence Schubotz
- MARUM-Center for Marine Environmental Sciences, University of Bremen
- Arthur Spivack
- Graduate School of Oceanography, University of Rhode Island
- Satoshi Tonai
- Department of Natural Science, Kochi University
- Tina Treude
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles (UCLA)
- Man-Yin Tsang
- University of Toronto
- Bernhard Viehweger
- MARUM-Center for Marine Environmental Sciences, University of Bremen
- David T. Wang
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology
- Emily Whitaker
- Department of Oceanography, Texas A&M University
- Yuzuru Yamamoto
- Department of Mathematical Science and Advanced Technology (MAT), Japan Agency for Marine-Earth Science and Technology
- Kiho Yang
- Department of Earth System Sciences, Yonsei University
- Masataka Kinoshita
- Earthquake Research Institute, University of Tokyo
- Lena Maeda
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Yusuke Kubo
- The Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology
- Yuki Morono
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Fumio Inagaki
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology
- Verena B. Heuer
- Department of Urban Management, Graduate School of Engineering, Kyoto University
- DOI
- https://doi.org/10.1186/s40645-018-0228-z
- Journal volume & issue
-
Vol. 5,
no. 1
pp. 1 – 10
Abstract
Abstract The study investigates the in-situ strength of sediments across a plate boundary décollement using drilling parameters recorded when a 1180-m-deep borehole was established during International Ocean Discovery Program (IODP) Expedition 370, Temperature-Limit of the Deep Biosphere off Muroto (T-Limit). Information of the in-situ strength of the shallow portion in/around a plate boundary fault zone is critical for understanding the development of accretionary prisms and of the décollement itself. Studies using seismic reflection surveys and scientific ocean drillings have recently revealed the existence of high pore pressure zones around frontal accretionary prisms, which may reduce the effective strength of the sediments. A direct measurement of in-situ strength by experiments, however, has not been executed due to the difficulty in estimating in-situ stress conditions. In this study, we derived a depth profile for the in-situ strength of a frontal accretionary prism across a décollement from drilling parameters using the recently established equivalent strength (EST) method. At site C0023, the toe of the accretionary prism area off Cape Muroto, Japan, the EST gradually increases with depth but undergoes a sudden change at ~ 800 mbsf, corresponding to the top of the subducting sediment. At this depth, directly below the décollement zone, the EST decreases from ~ 10 to 2 MPa, with a change in the baseline. This mechanically weak zone in the subducting sediments extends over 250 m (~ 800–1050 mbsf), corresponding to the zone where the fluid influx was discovered, and high-fluid pressure was suggested by previous seismic imaging observations. Although the origin of the fluids or absolute values of the strength remain unclear, our investigations support previous studies suggesting that elevated pore pressure beneath the décollement weakens the subducting sediments.
Keywords
- Plate boundary décollement
- Nankai Trough
- Excess fluid pressure
- Equivalent strength
- Drilling parameters
- International Ocean Discovery Program (IODP)
