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  • AGU (American Geophysical Union)  (2)
  • 2010-2014  (2)
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  • 1
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    Thermogenic methane injection via bubble transport into the upper Arctic Ocean from the hydrate-charged Vestnesa Ridge, Svalbard (2014)
    AGU (American Geophysical Union) | Wiley
    In:  Geochemistry, Geophysics, Geosystems, 15 (5). pp. 1945-1959.
    Details
    Publication Date: 2017-09-15
    Description: We use new gas-hydrate geochemistry analyses, echosounder data, and three-dimensional P-Cable seismic data to study a gas-hydrate and free-gas system in 1200 m water depth at the Vestnesa Ridge offshore NW Svalbard. Geochemical measurements of gas from hydrates collected at the ridge revealed a thermogenic source. The presence of thermogenic gas and temperatures of similar to 3.3 degrees C result in a shallow top of the hydrate stability zone (THSZ) at similar to 340 m below sea level (mbsl). Therefore, hydrate-skinned gas bubbles, which inhibit gas-dissolution processes, are thermodynamically stable to this shallow water depth. This was confirmed by hydroacoustic observations of flares in 2010 and 2012 reaching water depths between 210 and 480 mbsl. At the seafloor, bubbles are released from acoustically transparent zones in the seismic data, which we interpret as regions where free gas is migrating through the hydrate stability zone (HSZ). These intrusions result in vertical variations in the base of the HSZ (BHSZ) of up to similar to 150 m, possibly making the shallow hydrate reservoir more susceptible to warming. Such Arctic gas-hydrate and free-gas systems are important because of their potential role in climate change and in fueling marine life, but remain largely understudied due to limited data coverage in seasonally ice-covered Arctic environments.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2013GC005179
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Linked halokinesis and mud volcanism at the Mercator Mud Volcano, Gulf of Cadiz (2011)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Solid Earth, 116 . B05101.
    Details
    Publication Date: 2018-04-27
    Description: Mud volcanoes are seafloor expressions of focused fluid flow that are common in compressional tectonic settings. New high-resolution 3-D seismic data from the Mercator mud volcano (MMV) and an adjacent buried mud volcano (BMV) image the internal structure of the top 800 m of sediment at both mud volcanoes, revealing that both are linked and have been active episodically. The total volumes of extruded mud range between 0.15 and 0.35 km3 and 0.02–0.05 km3 for the MMV and the BMV, respectively. The pore water composition of surface sediment samples suggests that halokinesis has played an important role in the evolution of the mud volcanoes. We propose that erosion of the top of the Vernadsky Ridge that underlies the mud volcanoes activated salt movement, triggering deep migration of fluids, dissolution of salt, and sediment liquefaction and mobilization since the end of the Pliocene. Since beginning of mud volcanism in this area, the mud volcanoes erupted four times while there was only one reactivation of salt tectonics. This implies that there are other mechanisms that trigger mud eruptions. The stratigraphic relationship of mudflows from the MMV and BMV indicates that the BMV was triggered by the MMV eruptions. This may either be caused by loading-induced hydrofracturing within the BMV or due to a common feeder system for both mud volcanoes. This study shows that the mud volcanoes in the El Arraiche mud volcano field are long-lived features that erupt with intervals of several tens of thousands of years.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1029/2010JB008061
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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