Morphology of pockmarks along the western continental margin of India: Employing multibeam bathymetry and backscatter data

This study addresses the morphology of pockmarks along the western continental margin of India using multibeam bathymetry and backscatter data. Here, for the first time we have utilized the application of ArcGIS (Geographical Information System) for understanding the morphology of pockmarks from the...

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Bibliographic Details
Published in:Marine and petroleum geology 2010-12, Vol.27 (10), p.2107-2117
Main Authors: Dandapath, Sumanta, Chakraborty, Bishwajit, Karisiddaiah, Siddaiah M., Menezes, Andrew, Ranade, Govind, Fernandes, William, Naik, Davidas K., Prudhvi Raju, K.N.
Format: Article
Language:English
Subjects:
Arabian sea
Backscatter image
Backscattering
Bottom currents
Continental margin
Crude oil
Earth sciences
Earth, ocean, space
Elongation
Exact sciences and technology
Geographic information systems
Hydrocarbons
Marine
Marine geology
Morphology
Multibeam echo-sounder
Natural gas
Pockmark morphology
Seafloor seepage
Sedimentary rocks
Seepage
Separation
Submarines
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Summary:This study addresses the morphology of pockmarks along the western continental margin of India using multibeam bathymetry and backscatter data. Here, for the first time we have utilized the application of ArcGIS (Geographical Information System) for understanding the morphology of pockmarks from the western continental margin of India. The pockmarks observed in water depths of 145–330 m are circular, elliptical or elongated in plan-view, with an average length and width of 157 (±72) m and 83 (±19) m respectively. The average pockmark relief and perimeter are 1.9 (±0.9) m and 412 (±181) m, respectively. The pockmarks have average areas and volumes of 10 759 m 2 and 15 315 m 3 respectively. Spatial separation that coincides with 210 m isobath divides the pockmarks into two groups with differing distributions and morphologies. These pockmarks originated from seepages of biogenic or thermogenic gas or from pore fluids from deeper sources, migrated vertically along the faults. Besides a possible structural control, the pockmark morphologies are also affected by bottom currents and/or by submarine slumping. The average acoustic backscatter strength from pockmark centre is higher (−35 dB) than the average backscatter of the total area (−40 dB), which suggests their possible linkage to the precipitation of diagenitic minerals from biodegradation of seepage material.
ISSN:0264-8172
1873-4073
DOI:10.1016/j.marpetgeo.2010.09.005