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Heuer, Verena B; Inagaki, Fumio; Morono, Yuki; Kubo, Yusuke; Maeda, Lena; Bowden, Stephen; Cramm, Margaret; Henkel, Susann; Hirose, Takehiro; Homola, K.; Hoshino, Takao; Ijiri, Akira; Imachi, Hiroyuki; Kamiya, Nana; Kaneko, Masanori; Lagostina, Lorenzo; Manners, Hayley; McClelland, H.-L.; Metcalfe, K.; Okutsu, Natsumi; Pan, Donald; Raudsepp, Maija; Sauvage, Justine; Schubotz, Florence; Spivack, Arthur J.; Tonai, Satoshi; Treude, Tina; Tsang, Man-Yin; Viehweger, Bernhard; Wang, David T.; Whitaker, E; Yamamoto, Yuzuru; Yang, Kiho; Kinoshita, Masataka

doi:10.14379/iodp.pr.370.2017

Cited by 37 publications

(15 citation statements)

References 189 publications

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“…1). The borehole depth reached 1180 mbsf penetrating the frontal portion of the décollement zone at approximately 800 mbsf and basement igneous rock at approximately 1150 mbsf (Heuer et al 2017a). A total of 112 cores were recovered by combining three-types of coring methods: the hydraulic piston coring system (HPCS), the extended shoe coring system (ESCS), and rotary core barrel coring (RCB) (Heuer et al 2017b).…”

Section: Methods/experimentalmentioning

confidence: 99%

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

Hamada

Hirose

Ijiri

et al. 2018

Prog Earth Planet Sci

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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.

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Section: Methods/experimentalmentioning

confidence: 99%

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

Hamada

Hirose

Ijiri

et al. 2018

Prog Earth Planet Sci

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“…The XCT data used for this study was measured on core samples acquired at Site C0023 of IODP Expedition 370, Temperature-Limit of the Deep Biosphere off Muroto, Japan (Figure 2). This expedition was conducted in the Nankai Trough Subduction Zone, where the Philippine Sea Plate is subducting beneath the Japan Archipelago (Heuer et al, 2017a). The borehole reached 1,180 meters below the sea floor (mbsf), penetrating the frontal portion of the décollement (plate boundary fault) zone at 758.2-796.4 mbsf and basement igneous rocks at 1125.9 mbsf (Figure 3).…”

Section: Application To a Natural Dataset (Iodp Expedition 370)mentioning

confidence: 99%

“…(Heuer et al, 2017b). 112 cores were recovered in total and core recovery was 76% on average (Heuer et al, 2017a) (Figure 3).…”

Section: Application To a Natural Dataset (Iodp Expedition 370)mentioning

confidence: 99%

A New Method for Quality Control of Geological Cores by X-Ray Computed Tomography: Application in IODP Expedition 370

et al. 2019

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X-ray computed tomography (XCT) can be used to identify lithologies and deformation structures within geological core, with the potential for the identification processes to be applied automatically. However, because of drilling disturbance and other artifacts, the use of large XCT-datasets in automated processes requires methods of quality control that can be applied systematically. We propose a new systematic method for quality control of XCT data that applies numerical measures to CT slices, and from this obtains data reflective of core quality. Because the measures are numerical they can be applied quickly and consistently between different sections and cores. This quality control processing protocol produces downhole radiodensity profiles from mean CT-values that can be used for geological interpretation. The application of this quality control protocols was applied to XCT data from International Ocean Discovery Program (IODP) Expedition 370 Site C0023 located at the toe of the Nankai accretionary complex. The evaluation of core quality based on this protocol was found to be a good fit to standard-evaluations based on the visual description of core, and could be used to select samples free from drilling disturbance or contamination. The quality-controlled downhole mean CT-value profile has features that can be used to identify lithologies within a formation, the presence and type of deformation structures and to distinguish formations.

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“…Likewise, determining the temperature limits of the subsurface deep biosphere is a major aim of the scientific ocean drilling community (Challenge 6: what are the limits of life in the subseafloor?). Recently, IODP Expedition 370 sought to characterize the thermal limits of life in the organic-rich sediment deep biosphere (Heuer et al, 2017), but this drilling program did not cross the currently known temperature limit of life at 122°C (Kashefi and Lovley, 2003). Recent studies from Expedition 370 suggest a lower temperature of life in the subsurface, where other factors, such as nutrient availability, may depress the temperature of life (Heuer et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, IODP Expedition 370 sought to characterize the thermal limits of life in the organic-rich sediment deep biosphere (Heuer et al, 2017), but this drilling program did not cross the currently known temperature limit of life at 122°C (Kashefi and Lovley, 2003). Recent studies from Expedition 370 suggest a lower temperature of life in the subsurface, where other factors, such as nutrient availability, may depress the temperature of life (Heuer et al, 2017). Thus, Hole 504B, which reaches an estimated bottom-hole temperature of ~180°-190°C at ~2000 mbsf ( Figure F4; Guerin et al, 1996), is an ideal setting to test fundamental hypotheses about thermal limits of life.…”

Section: Introductionmentioning

confidence: 99%

Expedition 385T Preliminary Report: Panama Basin Crustal Architecture and Deep Biosphere

Tominaga¹,

Scientists²,

Orcutt³

et al. 2019

International Ocean Discovery Program Preliminary Report

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Untitled

Cited by 37 publications

References 189 publications

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

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

A New Method for Quality Control of Geological Cores by X-Ray Computed Tomography: Application in IODP Expedition 370

Expedition 385T Preliminary Report: Panama Basin Crustal Architecture and Deep Biosphere

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