Data Report: Structural Setting of the Leg 190 Muroto Transect

Moore, G. F.; Taira, Asahiko; Kuramoto, Shigeru; Ike, T.; Ito, Sotaro; Mochizuki, K.; Morita, S.; Nakamura, Yasuyuki

doi:10.2973/odp.proc.ir.190.102.2001

Cited by 12 publications

(5 citation statements)

References 16 publications

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“…[7] Previous interpretations of seismic reflection data in the region divide the outer accretionary prism into three distinct tectonic zones [Moore et al, 1999;Gulick et al, 2004]: (1) the protothrust zone (PTZ), (2) an imbricate thrust zone (ITZ), and (3) a region of out-of-sequence thrusting (OOST) ( Figure 3). The PTZ is bounded by the deformation front at its seaward edge and by the frontal thrust at its landward edge.…”

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

“…The OOST zone extends landward from the ITZ and is bounded by a large seafloor ridge. The bathymetric slope of the frontal ITZ region is 1-1.5°, and increases to ∼5-6°landward of the first OOST [Moore et al, 1999;Kimura et al, 2007]. In this study, we focus on the outer wedge toe of the Nankai prism, including the trench, PTZ, and frontal portion of the ITZ (Figure 3).…”

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

“…Although several studies have quantitatively estimated dewatering rates using numerical models [e.g., Bekins and Dreiss, 1992;Le Pichon et al, 1990] or global compilations of porosity data [Bray and Karig, 1985], water loss due to progressive compaction has generally not been rigorously quantified from data, mainly owing to lack of sufficient constraints on porosity distribution at individual margins. [4] Here, we examine a three-dimensional (3-D) seismic reflection volume acquired along the Muroto transect south of Shikoku Island in 1999 [Moore et al, 1999;Bangs et al, 2004;Gulick et al, 2004] (Figure 1). The Nankai Trough region is a focus for investigation partly because it has a 1300 year historical record of recurring great earthquakes, including the 1944 Tonankai (M w 8.1) and the 1946 Nankaido (M w 8.2) earthquakes [Ando, 1975].…”

Section: Introductionmentioning

confidence: 99%

“…Located off the southeast coast of Japan (Figure 1), the Nankai Trough has been extensively studied in recent years during Ocean Drilling Program (ODP) Legs 131,190, and 196 [Taira et al, 1991;Moore et al, 2001;Mikada et al, 2002]. Additionally, the region has been imaged by a series of seismic reflection and refraction surveys [Aoki et al, 1982;Leggett et al, 1985;Aoki et al, 1986;Moore et al, 1990Moore et al, , 1991Moore et al, , 1999Park et al, 1999Park et al, , 2000Kodaira et al, 2000]. A map view of the bathymetry of outer wedge study area, in addition to the orientation and location of specific profiles utilized in this study, are shown in Figure 2.…”

Section: Introductionmentioning

confidence: 99%

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Structural restoration of thrusts at the toe of the Nankai Trough accretionary prism off Shikoku Island, Japan: Implications for dewatering processes

Moore

Saffer

Studer

et al. 2011

Geochem Geophys Geosyst

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[1] A three-dimensional prestack depth-migrated seismic reflection data volume acquired off Shikoku Island, Japan covers the seaward portion of the Nankai Trough accretionary prism. We calculate and interpret total horizontal shortening lengths along three cross-sectional profiles through the volume, incorporating a technique addressing the significant amount of water volume sediments lose during accretion, constrained by porosity values derived from seismic interval velocities. The results reveal a total horizontal shortening of ∼40% within sediments of the first three thrust sheets in the wedge. This indicates that structural restorations applied to water-saturated young sediments, or other domains displaying large tectonicinduced porosity changes (e.g., accretionary prisms, subaerial and submarine fold and thrust belts), must account for the substantial amount of distributed compactive strain that affects the sediment during the initial stages of accretion. Our analysis of the porosity reduction also allows an estimate of dewatering rates across the outer accretionary wedge. We find that porosity loss and associated dewatering decrease with distance landward from the trench and correspond to a progressively decreasing contribution of diffuse compactive strain to the total shortening. We compute a dewatering rate of 10.5 km 3 /Ma (per km along strike) over the outer ∼7 km of the accretionary wedge. This relatively high rate of dewatering when compared to other well-studied subduction systems probably reflects the large thickness of accreted sediment and high sediment permeability that allows efficient consolidation. These results highlight the importance of considering distributed compactive strain in structural restorations for any setting where deformation occurs in sediments.

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Section: Geologic and Tectonic Settingmentioning

confidence: 99%

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structural restoration of thrusts at the toe of the Nankai Trough accretionary prism off Shikoku Island, Japan: Implications for dewatering processes

Moore

Saffer

Studer

et al. 2011

Geochem Geophys Geosyst

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show abstract

“…We have also processed these lines through filter, stack, and post-stack time migration. We also used a 3D seismic data set that was collected by a US-Japan Collaborative Program off Muroto in 1999 using the R/V Maurice Ewing (Moore et al 2001b). The acquisition parameters include a single 6 km streamer with 240 channels and a tuned 70 L (4270 in 3 ) air-gun array, and the resultant survey covered a region about 8 km wide and 80 km long.…”

Section: Data Acquisition and Processingmentioning

confidence: 99%

Variations in sediment thickness and type along the northern Philippine Sea Plate at the Nankai Trough

et al. 2008

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We documented regional and local variations in basement relief, sediment thickness, and sediment type in the Shikoku Basin, northern Philippine Sea Plate, which is subducting at the Nankai Trough. Seismic reflection data, tied with ocean drilling program drill cores, reveal that variations in the incoming sediment sequences are correlated with basement topography. We mapped the three-dimensional seismic facies distribution and measured representative seismic sequences and units. Trench-parallel seismic profiles show three regional provinces in the Shikoku Basin that are distinguished by the magnitude of basement relief and sediment thickness: Western (<200-400 m basement relief, >600 m sediment thickness), Central (>1500 m relief,~2000 m sediments), and Eastern (<600 m relief,~1200 m sediments) provinces. The total thickness of sediment in basement lows is as much as six times greater than that over basement highs. Turbidite sedimentation in the Shikoku Basin reflects basement control on deposition, leading to the local presence or absence of turbidite units deposited during the middle Oligocene to the middle Miocene. During the first phase of sedimentation, most basement lows were filled with turbidites, resulting in smooth seafloor morphology that does not reflect basement relief. A second phase of turbidite deposition in the Eastern Province was accompanied by significant amounts of hemipelagic sediments interbedded with turbidite layers compared to the other provinces because of its close proximity to the Izu-Bonin Island Arc. Both regional and local variations in basement topography and sediment thickness/type have caused lateral heterogeneities on the underthrusting plate that will, in turn, influence lateral fluid flow along the Nankai accretionary prism.

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Pore pressure penetrometers document high overpressure near the seafloor where multiple submarine landslides have occurred on the continental slope, offshore Louisiana, Gulf of Mexico

Flemings

Long

Dugan

et al. 2008

Earth and Planetary Science Letters

125

129

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Data Report: Structural Setting of the Leg 190 Muroto Transect

Cited by 12 publications

References 16 publications

Structural restoration of thrusts at the toe of the Nankai Trough accretionary prism off Shikoku Island, Japan: Implications for dewatering processes

Structural restoration of thrusts at the toe of the Nankai Trough accretionary prism off Shikoku Island, Japan: Implications for dewatering processes

Variations in sediment thickness and type along the northern Philippine Sea Plate at the Nankai Trough

Pore pressure penetrometers document high overpressure near the seafloor where multiple submarine landslides have occurred on the continental slope, offshore Louisiana, Gulf of Mexico

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