Regional Geophysics and Structural Framework of the Vancouver Island Margin Accretionary Prism

Hyndman, R. D.; Spence, G. D.; Yuan, T.; Davis, Earl E.

doi:10.2973/odp.proc.ir.146-1.002.1994

Cited by 32 publications

(34 citation statements)

References 65 publications

(125 reference statements)

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“…Comprehensive summaries of the regional geological framework and tectonics of the northern Cascadia margin were previously given by Hyndman et al (1994) and Hyndman (1995). Extensive reference lists therein provide further detailed information.…”

Section: General Plate Tectonic Regime and Structure Of Accretionary mentioning

confidence: 99%

“…Individual ridges are typically 20-30 km in length, a few kilometers in width, and generally parallel to the margin. The internal structure of the ridges is continuous along strike, but their shape is usually asymmetric with the steep flank facing seaward (e.g., Davis and Hyndman, 1989;Rohr, 1987;Hyndman et al, 1994). …”

Section: General Plate Tectonic Regime and Structure Of Accretionary mentioning

confidence: 99%

“…• Estimating the BSR reflection coefficient (Spence et al, 1991a(Spence et al, , 1991b(Spence et al, , 1995Hyndman et al, 1994;Yuan et al, 1994),…”

Section: Evidence Of Gas Hydratementioning

confidence: 99%

See 2 more Smart Citations

Gas hydrate on the northern Cascadia margin: regional geophysics and structural framework

Riedel¹,

Willoughby²,

Chen³

et al. 2006

Proceedings of the IODP

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Integrated Ocean Drilling Program Expedition 311 is based on extensive site survey data and historic research at the northern Cascadia margin since 1985. This research includes various regional geophysical surveys using a broad spectrum of seismic techniques, coring and logging by the Ocean Drilling Program Leg 146, heat flow measurements, shallow piston coring, and bottom video observations across a cold-vent field, as well as novel controlled-source electromagnetic and seafloor compliance surveying techniques. The wealth of data available allowed construction of structural cross-sections of the margin, development of models for the formation of gas hydrate in an accretionary prism, and estimation of gas hydrate and free gas concentrations. Expedition 311 established for the first time a transect of drill sites across the northern Cascadia margin to study the evolution of gas hydrate formation over the entire gas hydrate stability field of the accretionary complex. This paper reviews the tectonic framework at the northern Cascadia margin and summarizes the scientific studies that led to the drilling objectives of Expedition 311 Cascadia gas hydrate.

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Section: General Plate Tectonic Regime and Structure Of Accretionary mentioning

confidence: 99%

Section: General Plate Tectonic Regime and Structure Of Accretionary mentioning

confidence: 99%

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Gas hydrate on the northern Cascadia margin: regional geophysics and structural framework

Riedel¹,

Willoughby²,

Chen³

et al. 2006

Proceedings of the IODP

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“…Several additional multichannel surveys were acquired as part of a site survey for drilling by the international Ocean Drilling Program (ODP). A successful proposal to ODP resulted in two closely spaced shallow research wells into the mid continental slope off Vancouver Island on (ODP Sites 889 and 890) and a reference well in the adjacent deep sea Cascadia Basin 67 .…”

Section: Research Offshore Western Canadamentioning

confidence: 99%

Gas Hydrates Research Programs: An International Review

Gabitto¹,

Barrufet²

2009

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Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource.There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration.The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included.

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“…The Cascadia Margin is a site of active accretion, where a heterogeneous sequence of Neogene to Holocene sediments is scraped off the Juan de Fuca Plate as it subducts beneath the northwestern margin of North America (Cochrane et al, 1994;Hyndman et al, 1994;Shipboard Scientific Party, 1994) (Fig. 1).…”

Section: Tectonic and Sedimentological Settingmentioning

confidence: 99%

Microstructures in Accreted Sediments of the Cascadia Margin

Clennell¹,

Maltman²

1995

Proceedings of the Ocean Drilling Program, 146 Part 1 Scientific Results

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Deformed sediments collected from drilling at the Cascadia forearc were examined using optical and electron microscopy. A wide range of microstructures was encountered in a sample suite consisting mainly of fine-grained sediments. Most of the samples were recovered from the Oregon sector of the accretionary wedge, at Site 891, located at the deformation front, and Site 892, located on the second thrust ridge. For purposes of comparison, we also examined a small number of samples from the undeformed Cascadia Basin (Site 888) and from behind the second thrust ridge at the Vancouver Margin (Sites 889 and 890).Within each site, there is a strong compositional control on the style of deformation. Diatomaceous silts tend to show a more brittle style of deformation than either clay-rich silts or sands. Arrays of subparallel shear zones and incipiently scaly textures are developed in clay-rich sediments.At Site 891, intense deformation is largely confined to the vicinity of fault zones, where thick (tens of meters) intervals of incipiently scaly fabric and thin (tens of centimeters) zones of fault gouge are developed. Chaotic, small-scale folding is present at several horizons, and, in some cases, is overprinted by shear zones.Deformation at Site 892 is much more pervasive, with widespread fracturing producing a mosaic-like microstructure of angular blocky fragments. We interpret the blocky fractured texture as evidence for previous high pore fluid pressures and natural hydraulic fracturing within the Cascadia accretionary prism. Intervals of intense fracturing are transitional into a "pillowin-matrix" structure consisting of subrounded blocks of intact sediment within a sheared, clay-rich matrix. Darkened zones of gouge and broken formation, several meters thick, are interpreted as the main fault zones that have previously conducted fluids from depth, so that the fault rocks were chemically altered and mineralized.

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Regional Geophysics and Structural Framework of the Vancouver Island Margin Accretionary Prism

Cited by 32 publications

References 65 publications

Gas hydrate on the northern Cascadia margin: regional geophysics and structural framework

Gas hydrate on the northern Cascadia margin: regional geophysics and structural framework

Gas Hydrates Research Programs: An International Review

Microstructures in Accreted Sediments of the Cascadia Margin

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