Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Saffer, D. M.; Bekins, Barbara A.

doi:10.1029/98jb01983

Cited by 159 publications

(251 citation statements)

References 46 publications

(58 reference statements)

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“…Overpressures suggest that sediment permeability is insufficient to allow fluid expulsion [Screaton et al, 2002]. Long term fluid budgets suggest a zone of transient fluid flow within and/or below the décollement zone [Saffer and Bekins, 1998], but flow is minor relative to likely diffuse flow through the prism.…”

Section: Fractures Resistivity and Fluid Flowmentioning

confidence: 99%

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

McNeill

Ienaga

Tobin

et al. 2004

Geophysical Research Letters

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Borehole resistivity images from ODP Leg 196 allow rapid and complete qualitative assessment of deformation within the toe of the Nankai prism, Japan. Borehole breakouts were common within the prism but prominent in the trench‐wedge unit around the frontal thrust, suggesting reduced sediment strength. Breakouts indicate consistent σ2 orientations (∼050°), compatible with northwesterly convergence. Deformation is dominated by discrete zones, including the frontal thrust and décollement zone. Prism fractures trend ∼NE–SW, consistent with convergence. The décollement shows minimal deformation and the dominant structural trend is ∼N–S. Prism deformation zones are characterized by high resistivity (compaction), whereas the décollement is apparently dilated, both with conductive fractures. Distribution of fracture orientations varies between log units confirming lithologic and rheologic influence. Pore pressure is elevated within the décollement and the misalignment of conductive fractures may reduce permeability.

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Section: Fractures Resistivity and Fluid Flowmentioning

confidence: 99%

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

McNeill

Ienaga

Tobin

et al. 2004

Geophysical Research Letters

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“…[3] Fluids at convergent margins play an important role in the development of accretionary prisms [e.g., Carson et al, 1990;Moore et al, 1995;Saffer and Bekins, 1998]. Tectonic deformation at convergent margins releases fluids from nonlithified sediments [Moore et al, 1995], and the thermal alteration of primary minerals causes dehydration-related fluid flow [Moore and Vrolijk, 1992].…”

Section: Introductionmentioning

confidence: 99%

Compaction in the Nankai and Barbados accretionary prisms: New insights from logging‐while‐drilling data

Hunze

Wonik

2007

Geochem Geophys Geosyst

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[1] Sediment deformation, changes in physical properties, and fluid migration can be studied under welldefined conditions in accretionary prisms. Our investigations focused on the accretionary prisms of Barbados (Caribbean) and Nankai (Japan) to interpret the effects of compaction on different lithologies during accretion. The interpretation is based on very good quality logging-while-drilling data. Statistical data analysis is used to determine sediment composition and its specific physical properties. Finally, the sediments are decompacted to determine the initial compaction before accretion and thus to quantify both the lateral and the vertical compaction components. This investigation shows that different lithologies undergo similar compaction and porosity reduction. The porosity differences of selected sediment layers between adjacent sites are significantly lower in Nankai than in Barbados, which implies higher fluid expulsion in Nankai. Decompaction of these sediment layers proves that the lateral compaction component is higher than the vertical compaction component.

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“…Kastner et al, 1993). The observed freshening is partly explained by in situ diagenesis (compaction and thermally driven smectite dehydration) but also suggests some episodic lateral fluid flow along one or more sediment horizons (Moore, Taira, Klaus, et al, 2001;Saffer and Bekins, 1998;Underwood et al, 1993).…”

Section: Heat and Fluid Flowmentioning

confidence: 90%

Untitled

2016

International Ocean Discovery Program Scientific Prospectus

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Determining factors that limit the biomass, diversity, and activity of subseafloor microbial communities is one of the major scientific goals to be addressed by scientific ocean drilling. In the International Ocean Discovery Program (IODP) T-Limit Project, we will drill and core at new boreholes in the immediate vicinity of Ocean Drilling Program (ODP) Sites 1173, 1174, and 808 off Cape Muroto, Japan, in the central Nankai Trough, where anomalously high heat flow regimes result in temperatures of 110° to 140°C at the sediment/basement interface. Because of their location in the trench (Site 1173) and landward protothrust zone of the Nankai Trough accretionary prism (Sites 808 and 1174), the sites have different geotectonic and thermal histories that have resulted in contrasting (bio)geochemical modes of hydrocarbon gas production and consumption. Although the upper temperature limit appears well constrained at relatively energy-rich hydrothermal vent systems at just above 120°C, it is unknown in energy-starved sedimentary subseafloor settings but is generally presumed to be lower and thus expected to be covered by our target sites. During the IODP TLimit Project, we aim to• Comprehensively study the factors that control biomass, activity, and diversity of microbial communities in a subseafloor environment where temperatures increase from ~30° to ~130°C and thus likely encompasses the biotic-abiotic transition zone; and • Determine geochemical, geophysical, and hydrogeological characteristics in sediment and the underlying basaltic basement and elucidate if the supply of fluids containing thermogenic and/or geogenic nutrient and energy substrates may support subseafloor microbial communities in the Nankai accretionary complex.Because of the D/V Chikyu's schedule, these scientific objectives cannot be achieved within a single expedition. During the first TLimit expedition (370), we will drill and retrieve core samples from sedimentary sections (200-1210 m below seafloor) and basement basalt (1210-1260 m below seafloor) at the protothrust site near ODP Site 1174 and measure temperatures in situ.

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Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Cited by 159 publications

References 46 publications

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

Compaction in the Nankai and Barbados accretionary prisms: New insights from logging‐while‐drilling data

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