Geophysical and geochemical survey of a large marine pockmark on the Malin Shelf, Ireland
Szpak, Michal T.
Simpson, A. J.
Evans, Rob L.
Allen, C. C. R.
McNally, D. J.
Kelleher, B. P.
MetadataShow full item record
Marine pockmarks are a specific type of seabed geological setting resembling craters or pits and are considered seabed surface expressions of fluid flow in the subsurface. A large composite pockmark on the Malin Shelf, off the northern coast of Ireland was surveyed and ground truthed to assess its activity and investigate fluid related processes in the subsurface. Geophysical (including acoustic and electromagnetic) data confirmed the subsurface presence of signatures typical of fluids within the sediment. Shallow seismic profiling revealed a large shallow gas pocket and typical gas related indicators such as acoustic blanking and enhanced reflectors present underneath and around the large pockmark. Sulphate profiles indicate that gas from the shallow reservoir has been migrating upwards, at least recently. However, there are no chimney structures observed in the sub-bottom data and the migration pathways are not apparent. Electromagnetic data show slightly elevated electrical conductivity on the edges of the pockmarks and a drop below regional levels within the confines of the pockmark, suggesting changes in physical properties of the sediment. Nuclear Magnetic Resonance (NMR) experiments were employed to characterize the organic component of sediments from selected depths. Very strong microbial signatures were evident in all NMR spectra but microbes outside the pockmark appear to be much more active than inside. These observations coincide with spikes in conductivity and the lateral gas bearing body suggesting that there is an increase in microbial activity and biomass when gas is present.
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 13 (2012): Q01011, doi:10.1029/2011GC003787.
Suggested CitationGeochemistry Geophysics Geosystems 13 (2012): Q01011
Showing items related by title, author, creator and subject.
Newman, Kori R.; Cormier, Marie-Helene; Weissel, Jeffrey K.; Driscoll, Neal W.; Kastner, Miriam; Solomon, Evan A.; Robertson, Gretchen; Hill, Jenna C.; Singh, Hanumant; Camilli, Richard; Eustice, Ryan M. (2007-11)Detailed near-bottom investigation of a series of giant, kilometer scale, elongate pockmarks along the edge of the mid-Atlantic continental shelf confirms that methane is actively venting at the site. Dissolved methane ...
Projected changes in habitat suitability for 33 marine species on the Northeast US shelf based on species distribution models fit to bottom trawl survey data from the NOAA Northeast Fisheries Science Center Rogers, Lauren; Griffin, Robert; Young, Talia; Fuller, Emma; St. Martin, Kevin; Pinsky, Malin (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2019-05-22)Projected changes in habitat suitability for 33 marine species on the Northeast US shelf. Changes in habitat suitability are calculated based on species distribution models fit to bottom trawl survey data from the NOAA ...
SEASTAR: A mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas Gommenginger, Christine; Chapron, Bertrand; Hogg, Andy; Buckingham, Christian; Fox-Kemper, Baylor; Eriksson, Leif; Soulat, Francois; Ubelmann, Clement; Ocampo-Torres, Francisco; Nardelli, Bruno Buongiorno; Griffin, David; Lopez-Dekker, Paco; Knudsen, Per; Andersen, Ole; Stenseng, Lars; Stapleton, Neil; Perrie, Will; Violante-Carvalho, Nelson; Schulz-Stellenfleth, Johannes; Woolf, David K.; Isern-Fontanet, Jordi; Ardhuin, Fabrice; Klein, Patrice; Mouche, Alexis; Pascual, Ananda; Capet, Xavier; Hauser, Daniele; Stoffelen, Ad; Morrow, Rosemary; Aouf, Lotfi; Breivik, Øyvind; Fu, Lee-Lueng; Johannessen, Johnny A.; Aksenov, Yevgeny; Bricheno, Lucy; Hirschi, Joel; Martin, Adrien C. H.; Martin, Adrian P.; Nurser, A. J. George; Polton, Jeff; Wolf, Judith; Johnsen, Harald; Soloviev, Alexander; Jacobs, Gregg A.; Collard, Fabrice; Groom, Steve; Kudryavtsev, Vladimir; Wilkin, John L.; Navarro, Victor; Babanin, Alexander; Martin, Matthew; Siddorn, John; Saulter, Andrew; Rippeth, Tom; Emery, Bill; Maximenko, Nikolai; Romeiser, Roland; Graber, Hans C.; Alvera Azcarate, Aida; Hughes, Chris W.; Vandemark, Douglas; da Silva, Jose; Van Leeuwen, Peter Jan; Naveira Garabato, Alberto C.; Gemmrich, Johannes; Mahadevan, Amala; Marquez, Jose; Munro, Yvonne; Doody, Sam; Burbidge, Geoff (Frontiers Media, 2019-08-13)High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are ...