In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

Yohei Hamada* (Corresponding Author), 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 & 22 others 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

*Corresponding author for this work

Research output: Contribution to journalArticle

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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. [Figure not available: see fulltext.].

Original languageEnglish
Article number70
JournalProgress in Earth and Planetary Science
Volume5
Early online date3 Nov 2018
DOIs
Publication statusPublished - 1 Dec 2018

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plate boundary
accretionary prism
trough
sediment
drilling
pore pressure
fluid
in situ stress
ocean
fluid pressure
biosphere
seismic reflection
fault zone
borehole
in situ
experiment
temperature
parameter

Keywords

  • Drilling parameters
  • DV Chikyu
  • Equivalent strength
  • Excess fluid pressure
  • International Ocean Discovery Program (IODP)
  • Nankai Trough
  • Plate boundary décollement
  • Site C0023
  • Temperature-Limit of the Deep Biosphere off Muroto (T-Limit)

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Cite this

In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough. / Hamada, Yohei (Corresponding Author); Hirose, Takehiro; Ijiri, Akira; Yamada, Yasuhiro; Sanada, Yoshinori; Saito, Saneatsu; Sakurai, Noriaki; Sugihara, Takamitsu; Yokoyama, Takahiro; Saruhashi, Tomokazu; Hoshino, Tatsuhiko; Kamiya, Nana; Bowden, Stephen; Cramm, Margaret; Henkel, Susann; Homola, Kira; Imachi, Hiroyuki; Kaneko, Masanori; Lagostina, Lorenzo; Manners, Hayley; McClelland, Harry Luke; Metcalfe, Kyle; Okutsu, Natsumi; Pan, Donald; Raudsepp, Maija Jocelyn; Sauvage, Justine; Schubotz, Florence; Spivack, Arthur; Tonai, Satoshi; Treude, Tina; Tsang, Man Yin; Viehweger, Bernhard; Wang, David T.; Whitaker, Emily; Yamamoto, Yuzuru; Yang, Kiho; Kinoshita, Masataka; Maeda, Lena; Kubo, Yusuke; Morono, Yuki; Inagaki, Fumio; Heuer, Verena B.

In: Progress in Earth and Planetary Science, Vol. 5, 70, 01.12.2018.

Research output: Contribution to journalArticle

Hamada, Y, Hirose, T, Ijiri, A, Yamada, Y, Sanada, Y, Saito, S, Sakurai, N, Sugihara, T, Yokoyama, T, Saruhashi, T, Hoshino, T, Kamiya, N, Bowden, S, Cramm, M, Henkel, S, Homola, K, Imachi, H, Kaneko, M, Lagostina, L, Manners, H, McClelland, HL, Metcalfe, K, Okutsu, N, Pan, D, Raudsepp, MJ, Sauvage, J, Schubotz, F, Spivack, A, Tonai, S, Treude, T, Tsang, MY, Viehweger, B, Wang, DT, Whitaker, E, Yamamoto, Y, Yang, K, Kinoshita, M, Maeda, L, Kubo, Y, Morono, Y, Inagaki, F & Heuer, VB 2018, 'In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough', Progress in Earth and Planetary Science, vol. 5, 70. https://doi.org/10.1186/s40645-018-0228-z
Hamada, Yohei ; Hirose, Takehiro ; Ijiri, Akira ; Yamada, Yasuhiro ; Sanada, Yoshinori ; Saito, Saneatsu ; Sakurai, Noriaki ; Sugihara, Takamitsu ; Yokoyama, Takahiro ; Saruhashi, Tomokazu ; Hoshino, Tatsuhiko ; Kamiya, Nana ; Bowden, Stephen ; Cramm, Margaret ; Henkel, Susann ; Homola, Kira ; Imachi, Hiroyuki ; Kaneko, Masanori ; Lagostina, Lorenzo ; Manners, Hayley ; McClelland, Harry Luke ; Metcalfe, Kyle ; Okutsu, Natsumi ; Pan, Donald ; Raudsepp, Maija Jocelyn ; Sauvage, Justine ; Schubotz, Florence ; Spivack, Arthur ; Tonai, Satoshi ; Treude, Tina ; Tsang, Man Yin ; Viehweger, Bernhard ; Wang, David T. ; Whitaker, Emily ; Yamamoto, Yuzuru ; Yang, Kiho ; Kinoshita, Masataka ; Maeda, Lena ; Kubo, Yusuke ; Morono, Yuki ; Inagaki, Fumio ; Heuer, Verena B. / In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough. In: Progress in Earth and Planetary Science. 2018 ; Vol. 5.
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title = "In-situ mechanical weakness of subducting sediments beneath a plate boundary d{\'e}collement in the Nankai Trough",
abstract = "The study investigates the in-situ strength of sediments across a plate boundary d{\'e}collement 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 d{\'e}collement 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 d{\'e}collement 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 d{\'e}collement 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 d{\'e}collement weakens the subducting sediments. [Figure not available: see fulltext.].",
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author = "Yohei Hamada and Takehiro Hirose and Akira Ijiri and Yasuhiro Yamada and Yoshinori Sanada and Saneatsu Saito and Noriaki Sakurai and Takamitsu Sugihara and Takahiro Yokoyama and Tomokazu Saruhashi and Tatsuhiko Hoshino and Nana Kamiya and Stephen Bowden and Margaret Cramm and Susann Henkel and Kira Homola and Hiroyuki Imachi and Masanori Kaneko and Lorenzo Lagostina and Hayley Manners and McClelland, {Harry Luke} and Kyle Metcalfe and Natsumi Okutsu and Donald Pan and Raudsepp, {Maija Jocelyn} and Justine Sauvage and Florence Schubotz and Arthur Spivack and Satoshi Tonai and Tina Treude and Tsang, {Man Yin} and Bernhard Viehweger and Wang, {David T.} and Emily Whitaker and Yuzuru Yamamoto and Kiho Yang and Masataka Kinoshita and Lena Maeda and Yusuke Kubo and Yuki Morono and Fumio Inagaki and Heuer, {Verena B.}",
note = "Acknowledgements This research used data provided by the International Ocean Discovery Program (IODP). This manuscript was improved following discussions with Prof. G Kimura and Dr. Jun Kameda. We are grateful to Dr. W. Tanikawa for his repeated help with the numerical calculations. We also thank M Ikari and one anonymous reviewer for their constructive comments. The authors wish to thank Mantle Quest Japan for operating the vessel and drillings. We received generous supports from Technology Department in CDEX. We gratefully acknowledge the support provided by the operational staff of D/V Chikyu and the onboard laboratory technicians (Marine Works Japan). Funding This study was supported by JSPS KAKENHI grant 16H04064, 15H05717.",
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T1 - In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

AU - Hamada, Yohei

AU - Hirose, Takehiro

AU - Ijiri, Akira

AU - Yamada, Yasuhiro

AU - Sanada, Yoshinori

AU - Saito, Saneatsu

AU - Sakurai, Noriaki

AU - Sugihara, Takamitsu

AU - Yokoyama, Takahiro

AU - Saruhashi, Tomokazu

AU - Hoshino, Tatsuhiko

AU - Kamiya, Nana

AU - Bowden, Stephen

AU - Cramm, Margaret

AU - Henkel, Susann

AU - Homola, Kira

AU - Imachi, Hiroyuki

AU - Kaneko, Masanori

AU - Lagostina, Lorenzo

AU - Manners, Hayley

AU - McClelland, Harry Luke

AU - Metcalfe, Kyle

AU - Okutsu, Natsumi

AU - Pan, Donald

AU - Raudsepp, Maija Jocelyn

AU - Sauvage, Justine

AU - Schubotz, Florence

AU - Spivack, Arthur

AU - Tonai, Satoshi

AU - Treude, Tina

AU - Tsang, Man Yin

AU - Viehweger, Bernhard

AU - Wang, David T.

AU - Whitaker, Emily

AU - Yamamoto, Yuzuru

AU - Yang, Kiho

AU - Kinoshita, Masataka

AU - Maeda, Lena

AU - Kubo, Yusuke

AU - Morono, Yuki

AU - Inagaki, Fumio

AU - Heuer, Verena B.

N1 - Acknowledgements This research used data provided by the International Ocean Discovery Program (IODP). This manuscript was improved following discussions with Prof. G Kimura and Dr. Jun Kameda. We are grateful to Dr. W. Tanikawa for his repeated help with the numerical calculations. We also thank M Ikari and one anonymous reviewer for their constructive comments. The authors wish to thank Mantle Quest Japan for operating the vessel and drillings. We received generous supports from Technology Department in CDEX. We gratefully acknowledge the support provided by the operational staff of D/V Chikyu and the onboard laboratory technicians (Marine Works Japan). Funding This study was supported by JSPS KAKENHI grant 16H04064, 15H05717.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - 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. [Figure not available: see fulltext.].

AB - 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. [Figure not available: see fulltext.].

KW - Drilling parameters

KW - DV Chikyu

KW - Equivalent strength

KW - Excess fluid pressure

KW - International Ocean Discovery Program (IODP)

KW - Nankai Trough

KW - Plate boundary décollement

KW - Site C0023

KW - Temperature-Limit of the Deep Biosphere off Muroto (T-Limit)

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U2 - 10.1186/s40645-018-0228-z

DO - 10.1186/s40645-018-0228-z

M3 - Article

VL - 5

JO - Progress in Earth and Planetary Science

JF - Progress in Earth and Planetary Science

SN - 2197-4284

M1 - 70

ER -