Variations in pockmark composition at the Vestnesa Ridge; insights from marine controlled source electromagnetic and seismic data

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doi: 10.1002/2016GC006700
Author(s): Goswami, Bedanta K.; Weitemeyer, Karen A.; Bunz, Stefan; Minshull, Timothy A.; Westbrook, Graham K.; Ker, Stephan; Sinha, Martin C.
Author Affiliation(s): Primary:
University of Southampton, National Oceanography Centre Southampton, Southamptom, United Kingdom
Arctic University of Norway, Norway
University of Birmingham, United Kingdom
Institut Français de Recherche pour l'Exploitation de la Mer, France
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 18(3), p.1111-1125. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 44 refs.; illus., incl. sketch map
Summary: The Vestnesa Ridge marks the northern boundary of a known submarine gas hydrate province in the west Svalbard margin. Several seafloor pockmarks at the eastern segment of the ridge are sites of active methane venting. Until recently, seismic reflection data were the main tool for imaging beneath the ridge. Coincident controlled source electromagnetic (CSEM), high-resolution two-dimensional (2-D) airgun, sweep frequency SYSIF, and three-dimensional (3-D) p-cable seismic reflection data were acquired at the south-eastern part of the ridge between 2011 and 2013. The CSEM and seismic data contain profiles across and along the ridge, passing several active and inactive pockmarks. Joint interpretation of resistivity models obtained from CSEM and seismic reflection data provides new information regarding the fluid composition beneath the pockmarks. There is considerable variation in transverse resistance and seismic reflection characteristics of the gas hydrate stability zone (GHSZ) between the ridge flanks and chimneys beneath pockmarks. Layered seismic reflectors on the flanks are associated with around 300 Ωm2 transverse resistance, whereas the seismic reflectors within the chimneys exhibit amplitude blanking and chaotic patterns. The transverse resistance of the GHSZ within the chimneys vary between 400 and 1200 Ωm2. Variance attributes obtained from the 3-D p-cable data also highlight faults and chimneys, which coincide with the resistivity anomalies. Based on the joint data interpretation, widespread gas hydrate presence is likely at the ridge, with both hydrates and free gas contained within the faults and chimneys. However, at the active chimneys the effect of gas likely dominates the resistive anomalies. Abstract Copyright (2017), . The Authors.
Year of Publication: 2017
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 20 Geophysics, Applied; Aliphatic hydrocarbons; Alkanes; Arctic Ocean; Arctic region; Barents Sea; Bottom features; Chimneys; Electrical anomalies; Electromagnetic methods; Gas hydrates; Gas seeps; Geophysical methods; Geophysical surveys; Hydrocarbons; Knipovich Ridge; Leg 162; Marine methods; Methane; Norwegian Sea; ODP Site 986; Ocean Drilling Program; Ocean floors; Organic compounds; Pockmarks; Reflection methods; Resistivity; Seismic methods; Surveys; Svalbard; Three-dimensional models; Two-dimensional models; Vents; Vestnesa Ridge
Coordinates: N750000 N800000 E0200000 E0000000
Record ID: 2017060800
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union