Shallow stratigraphic control on pockmark distribution in north temperate estuaries
Brothers, Laura L.
Kelley, Joseph T.
Belknap, Daniel F.
Barnhardt, Walter A.
Andrews, Brian D.
Hughes Clarke, John E.
MetadataShow full item record
Pockmark fields occur throughout northern North American temperate estuaries despite the absence of extensive thermogenic hydrocarbon deposits typically associated with pockmarks. In such settings, the origins of the gas and triggering mechanism(s) responsible for pockmark formation are not obvious. Nor is it known why pockmarks proliferate in this region but do not occur south of the glacial terminus in eastern North America. This paper tests two hypotheses addressing these knowledge gaps: 1) the region's unique sea-level history provided a terrestrial deposit that sourced the gas responsible for pockmark formation; and 2) the region's physiography controls pockmarks distribution. This study integrates over 2500 km of high-resolution swath bathymetry, Chirp seismic reflection profiles and vibracore data acquired in three estuarine pockmark fields in the Gulf of Maine and Bay of Fundy. Vibracores sampled a hydric paleosol lacking the organic-rich upper horizons, indicating that an organic-rich terrestrial deposit was eroded prior to pockmark formation. This observation suggests that the gas, which is presumably responsible for the formation of the pockmarks, originated in Holocene estuarine sediments (loss on ignition 3.5–10%), not terrestrial deposits that were subsequently drowned and buried by mud. The 7470 pockmarks identified in this study are non-randomly clustered. Pockmark size and distribution relate to Holocene sediment thickness (r2 = 0.60), basin morphology and glacial deposits. The irregular underlying topography that dictates Holocene sediment thickness may ultimately play a more important role in temperate estuarine pockmark distribution than drowned terrestrial deposits. These results give insight into the conditions necessary for pockmark formation in nearshore coastal environments.
This paper is not subject to U.S. copyright. The definitive version was published in Marine Geology 329-331 (2012): 34-45, doi:10.1016/j.margeo.2012.09.006.
Suggested CitationArticle: Brothers, Laura L., Kelley, Joseph T., Belknap, Daniel F., Barnhardt, Walter A., Andrews, Brian D., Legere, Christine, Hughes Clarke, John E., "Shallow stratigraphic control on pockmark distribution in north temperate estuaries", Marine Geology 329-331 (2012): 34-45, DOI:10.1016/j.margeo.2012.09.006, https://hdl.handle.net/1912/5759
Showing items related by title, author, creator and subject.
Szpak, Michal T.; Monteys, Xavier; O'Reilly, S.; Simpson, A. J.; Garcia, Xavier; Evans, Rob L.; Allen, C. C. R.; McNally, D. J.; Courtier-Murias, D.; Kelleher, B. P. (American Geophysical Union, 2012-01-19)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 ...
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 ...
Munoz, Araceli; Acosta, Juan; Cristobo, J.; Druet, M.; Uchupi, Elazar; Atlantis Group 1 (2013-03)We study an area little known of the Atlantic Patagonian margin from 44˚30’S to 47˚40’S and from 59˚W to nearly 61˚W. The multi-beam bathymetry coupled with high resolution seismic reflection profiles, have provided details ...