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  • 1
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    Gas hydrate on the northern Cascadia margin: regional geophysics and structural framework (2006)
    Texas A & M University
    In:  Proceedings of the Integrated Ocean Drilling Program, 311 .
    Details
    Publication Date: 2020-06-08
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.2204/iodp.proc.311.109.2006
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Marine CSEM Using a Bottom -Towed System to Explore Submarine Cold Vent Sites in Cascadia and New Zealand (2007)
    In:  [Talk] In: IUGG 24th General Assembly 2007, 02.-13.07, Pergugia, Italy .
    Details
    Publication Date: 2019-09-23
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Limitation Availability
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    OceanRep: Talk
  • 3
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    Gas Hydrate Offshore Vancouver Island, Northern Cascadia Margin (2009)
    American Association of Petroleum Geologists
    In:  In: Natural Gas Hydrates: Energy Resource Potential and Associated Geologic Hazards. , ed. by Collett, T., Johnson, A., Knapp, C. and Boswell, R. AAPG Memoir, 89 . American Association of Petroleum Geologists, Tulsa, Oklahoma, pp. 433-450.
    Details
    Publication Date: 2019-01-21
    Description: This chapter reviews the extensive geophysical studies and Ocean Drilling Program (ODP) results that provide constraints on the occurrence, distribution, and concentration of deep-sea gas hydrate beneath the northern Cascadia margin offshore Vancouver Island. Most of this information comes from a wide range of seismic surveys and includes the mapping of the bottom-simulating reflector (BSR), as well as estimating gas-hydrate and free-gas concentrations. Recent additional constraints on the distribution and concentration of gas hydrate come from sea-floor-towed, controlled-source electromagnetic surveying and sea-floor compliance studies. These surveys and studies have been primarily deployed around a cold vent field, where seismic data show several broad blank zones, interpreted as fault-related conduits for focused fluid-gas migration, and where gas hydrate has been recovered in piston cores at the sea floor. Results from the ODP Leg 146 and the recently completed Integrated Ocean Drilling Program (IODP) Expedition 311 further constrain concentration estimates for gas hydrate and free gas in the sediments along the margin and also give insight into the complex formation mechanisms and controlling factors for gas hydrate occurrence in an accretionary complex. This summary was first presented in September 2004 at the AAPG Hedberg Research Conference on gas hydrates. Subsequently, 1 yr later, the drilling of IODP Expedition 311 resulted in a significant amount of new information and insight into the occurrence and formation processes of gas hydrate at the northern Cascadia margin. This chapter provides only a short summary of the results from that IODP Expedition. Reviews of the results from that drill coring and the downhole measurements are in progress.
    Type: Book chapter , NonPeerReviewed
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    OceanRep: Book chapter
  • 4
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    Focused Fluid Flow along the Nootka Fault Zone and Continental slope, Explorer‐Juan de Fuca Plate Boundary (2020)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2023-02-08
    Description: Key Points: - Fluid flow is focused along Nootka Fault traces resulting in shallow bright spots - Two seafloor mounds are the result of basaltic intrusions in the Nootka Fault zone - Gas hydrates occur at the Nootka Slope and are imaged seismically as bottom- simulating reflectors suggesting a regional heat-flow of ~80 mW/m2 along the slope Abstract Geophysical and geochemical data indicate there is abundant fluid expulsion in the Nootka fault zone (NFZ) between the Juan de Fuca and Explorer plates and the Nootka continental slope. Here we combine observations from 〉 20 years of investigations to demonstrate the nature of fluid‐flow along the NFZ, which is the seismically most active region off Vancouver Island. Seismicity reaching down to the upper mantle is linked to near‐seafloor manifestation of fluid flow through a network of faults. Along the two main fault traces, seismic reflection data imaged bright spots 100 – 300 m below seafloor that lie above changes in basement topography. The bright spots are conformable to sediment layering, show opposite‐to‐seafloor reflection polarity, and are associated with frequency‐reduction and velocity push‐down indicating the presence of gas in the sediments. Two seafloor mounds ~15 km seaward of the Nootka slope are underlain by deep, non‐conformable high amplitude reflective zones. Measurements in the water column above one mound revealed a plume of warm water, and bottom‐video observations imaged hydrothermal vent system biota. Pore fluids from a core at this mound contain predominately microbial methane (C1) with a high proportion of ethane (C2) yielding C1/C2 ratios 〈 500 indicating a possible slight contribution from a deep source. We infer the reflective zones beneath the two mounds are basaltic intrusions that create hydrothermal circulation within the overlying sediments. Across the Nootka continental slope, gas hydrate related bottom‐simulating reflectors are widespread and occur at depths indicating heat‐flow values of 80 – 90 mW/m2.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    Electronic Resource
    Electronic Resource
    Changes in Immune Function in Relapsing Multiple Sclerosis Correlate with Disease Activity As Assessed by Magnetic Resonance Imaging (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 540 (1988), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1988.tb27185.x
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    Paper (German National Licenses)
    Fulltext
  • 6
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    Focused Fluid Flow Along the Nootka Fault Zone and Continental Slope, Explorer-Juan de Fuca Plate Boundary (2021)
    Details
    Publication Date: 2021-10-11
    Description: Geophysical and geochemical data indicate there is abundant fluid expulsion in the Nootka fault zone (NFZ) between the Juan de Fuca and Explorer plates and the Nootka continental slope. Here we combine observations from 〉20 years of investigations to demonstrate the nature of fluid-flow along the NFZ, which is the seismically most active region off Vancouver Island. Seismicity reaching down to the upper mantle is linked to near-seafloor manifestation of fluid flow through a network of faults. Along the two main fault traces, seismic reflection data imaged bright spots 100–300 m below seafloor that lie above changes in basement topography. The bright spots are conformable to sediment layering, show opposite-to-seafloor reflection polarity, and are associated with frequency reduction and velocity push-down indicating the presence of gas in the sediments. Two seafloor mounds ~15 km seaward of the Nootka slope are underlain by deep, nonconformable high-amplitude reflective zones. Measurements in the water column above one mound revealed a plume of warm water, and bottom-video observations imaged hydrothermal vent system biota. Pore fluids from a core at this mound contain predominately microbial methane (C1) with a high proportion of ethane (C2) yielding C1/C2 ratios 〈500 indicating a possible slight contribution from a deep source. We infer the reflective zones beneath the two mounds are basaltic intrusions that create hydrothermal circulation within the overlying sediments. Across the Nootka continental slope, gas hydrate-related bottom-simulating reflectors are widespread and occur at depths indicating heat flow values of 80–90 mW/m2.
    Keywords: 551 ; fluid flow ; Nootka transform fault ; gas hydrate ; intrusion ; heat flow
    Language: English
    Type: map
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    CITATION GEO-LEO
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