Automated feature extraction and spatial organization of seafloor pockmarks, Belfast Bay, Maine, USA

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2010-08-20Author
Andrews, Brian D.
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Brothers, Laura L.
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Barnhardt, Walter A.
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https://hdl.handle.net/1912/4169As published
https://doi.org/10.1016/j.geomorph.2010.08.009DOI
10.1016/j.geomorph.2010.08.009Keyword
Pockmarks; Geomorphometry; Marine geology; MethaneAbstract
Seafloor pockmarks occur worldwide and may represent millions of m3 of continental shelf erosion, but few numerical analyses of their morphology and spatial distribution of pockmarks exist. We introduce a quantitative definition of pockmark morphology and, based on this definition, propose a three-step geomorphometric method to identify and extract pockmarks from high-resolution swath bathymetry. We apply this GIS-implemented approach to 25 km2 of bathymetry collected in the Belfast Bay, Maine USA pockmark field. Our model extracted 1767 pockmarks and found a linear pockmark depth-to-diameter ratio for pockmarks field-wide. Mean pockmark depth is 7.6 m and mean diameter is 84.8 m. Pockmark distribution is non-random, and nearly half of the field's pockmarks occur in chains. The most prominent chains are oriented semi-normal to the steepest gradient in Holocene sediment thickness. A descriptive model yields field-wide spatial statistics indicating that pockmarks are distributed in non-random clusters. Results enable quantitative comparison of pockmarks in fields worldwide as well as similar concave features, such as impact craters, dolines, or salt pools.
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This paper is not subject to U.S. copyright. The definitive version was published in Geomorphology 124 (2010): 55-64, doi:10.1016/j.geomorph.2010.08.009.
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Geomorphology 124 (2010): 55-64Related items
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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.; Legere, Christine; Hughes Clarke, John E. (Elsevier B.V., 2012-09-27)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 ... -
Geophysical and geochemical survey of a large marine pockmark on the Malin Shelf, Ireland
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More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: implications for pockmark field longevity
Brothers, Laura L.; Kelley, Joseph T.; Belknap, Daniel F.; Barnhardt, Walter A.; Andrews, Brian D.; Maynard, Melissa Landon (Springer, 2011-02-07)Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes ...