Pore pressure development and progressive dewatering in underthrust sediments at the Costa Rican subduction margin: Comparison with northern Barbados and Nankai

Saffer, D. M.

doi:10.1029/2002jb001787

Cited by 122 publications

(204 citation statements)

References 46 publications

(93 reference statements)

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“…However, based on the compaction trend for the slope sediments above and below the thrust wedge inferred from resistivity data (Conin et al, 2008), the overridden slope sediments do not appear to be underconsolidated, as might be the case for compaction disequilibrium (Hart et al, 1995;Saffer, 2003). Thus we conclude that the thrust wedge at Site C0010 is overcompacted, meaning that its porosity is anomalously low for its burial depth.…”

Section: Architecture and Along-strike Variation Of The Megasplay Faultmentioning

confidence: 93%

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Saffer¹,

McNeill²,

Araki³

et al. 2009

IODP Preliminary Report

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Section: Architecture and Along-strike Variation Of The Megasplay Faultmentioning

confidence: 93%

Untitled

Saffer¹,

McNeill²,

Araki³

et al. 2009

IODP Preliminary Report

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Section: Laboratory Testing Methodologymentioning

confidence: 99%

“…Sample disturbance can produce consolidation data with poorly defined σ pc ′ (Santagata and Germaine, 2002). Saffer (2003) and Dugan and Germaine (2008) present methods to estimate error on interpreted preconsolidation stresses.To complement the geotechnical data, we also characterized the grain-size distribution for the vertically oriented specimens (Tables T1, T3). All grain-size analyses followed the ASTM standard for particle-size analysis (ASTM International, 2003).…”

mentioning

confidence: 99%

Data report: permeability, compressibility, stress state, and grain size of shallow sediments from Sites C0004, C0006, C0007, and C0008 of the Nankai accretionary complex

Dugan¹,

Daigle²

2011

Proceedings of the IODP

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Constant-rate-of-strain consolidation experiments and grain-size analyses are used to characterize the flow and deformation behavior and grain-size distribution of vertically and horizontally oriented specimens from 0 to 100 meters below seafloor at Integrated Ocean Drilling Program Expedition 316 Sites C0004 and C0006-C0008. Interpreted in situ permeability was generally <10 -14 m 2 , but values ranged from 4.6 × 10 -14 m 2 to 1.1 × 10 -16 m 2 and do not exhibit any definitive trends with depth or grain size.Compression indexes, defining stress-strain behavior during normal consolidation, ranged from 0.15 to 0.9. The overconsolidation ratio (OCR) of vertically oriented specimens, which relates the in situ effective stress to the hydrostatic effective vertical stress, decreased downhole, and most samples had an OCR >1. Grain-size characterization by settling analysis documented that these shallow sediments are dominated by silt and/or clay, with median grain sizes ranging from 0.003 to 0.026 mm, excluding one sand-rich specimen. IntroductionIntegrated Ocean Drilling Program (IODP) Expedition 316 conducted research to understand deformation, fault zone properties, structural partitioning, and fluid flow in the frontal thrust and shallow zone of the megasplay of the Nankai subduction zone (see Screaton et al., 2009). The goals of IODP Expedition 316 fit within the larger objectives of the multiphase Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) to constrain, monitor, and understand faulting and seismogenesis along megathrusts (Tobin and Kinoshita, 2006).We focus on the consolidation and flow behavior of shallow sediments, which will be integrated with other shore-based research to understand fluid budgets and deformation of sediments within the Nankai accretionary complex. Whole-round samples were used in constant-rate-of-strain (CRS) consolidation experiments to measure the compression behavior and to estimate the in situ flow properties. Vertically and horizontally oriented specimens from Expedition 316 Sites C0004 and C0006-C0008 were tested to constrain anisotropy of bulk sediment properties in the shallow (<100 meters below seafloor [mbsf]) subsurface (Table T1). We also completed grain-size analysis of geotechnical samples (Table Data report Laboratory testing methodologyWhole-round core samples from Sites C0004 and C0006-C0008 (Table T1) were capped and sealed after collection and stored at 4°C to help maintain the natural water content. Samples were taken out of the sealed core liner to conduct CRS consolidation experiments and grain-size analysis following American Society for Testing and Materials (ASTM) International standards (ASTM International 2003; ASTM International, 2006). CRS consolidation experiments are performed at room temperature (20°C) in a rigid confining ring to maintain uniaxial strain. Each specimen was trimmed using a trimming jig, a wire saw, and a sharp-edged spatula to minimize disturbance during preparation and to provide a specimen diameter that was the exact...

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“…Ge and Garven built a two-dimensional numerical model to investigate the effects of the instantaneous compressional tectonics on the regional groundwater flow [17]. Saffer [18], Ge and Screaton [19], and Zhou and Hou [20] considered the impacts of the effective stress on fault deformations or other structural developments in the subsurface geological evolution. All above studies considered the case of instantaneous loading rather than continuous loading.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Hydromechanical Modeling during Shearing by Nonuniform Crust Movement

2017

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Hydromechanical modeling of a geological formation under shearing by the nonuniform crust movement during 10000 years was carried out to investigate the solid stress and pore pressure coupling processes of the formation from the intact to the fractured or faulted. Two three-dimensional numerical models were built and velocities in opposite directions were applied on the boundaries to produce the shearing due to the nonuniform crust movement. The results show that the stress and pore pressure became more and more concentrated in and around the middle of the formation as time progresses. In Model I with no fault, stress and pore pressure are concentrated in the middle of the model during shearing; however, in Model II with a fault zone of weakened mechanical properties, they are more complex and concentrated along the sides of the fault zone and the magnitudes decreased. The distribution of stress determines pore pressure which in turn controls fluid flow. Fluid flow occurs in the middle in Model I but along the sides of the fault zone in Model II. The results of this study improve our understanding of the rock-fluid interaction processes affected by crustal movement and may guide practical investigations in geological formations.

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Pore pressure development and progressive dewatering in underthrust sediments at the Costa Rican subduction margin: Comparison with northern Barbados and Nankai

Cited by 122 publications

References 46 publications

Untitled

Untitled

Data report: permeability, compressibility, stress state, and grain size of shallow sediments from Sites C0004, C0006, C0007, and C0008 of the Nankai accretionary complex

Three-Dimensional Hydromechanical Modeling during Shearing by Nonuniform Crust Movement

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