Type |
Article |
Date |
2016-01 |
Language |
English |
Author(s) |
Riboulot Vincent1, Sultan Nabil1, Imbert P.2, Ker Stephan1 |
Affiliation(s) |
1 : IFREMER, Inst CARNOT EDROME, Ctr Brest, Brest, France. 2 : TOTAL, Pau, France. |
Source |
Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2016-01 , Vol. 434 , P. 252-263 |
DOI |
10.1016/j.epsl.2015.11.047 |
WOS© Times Cited |
39 |
Keyword(s) |
pockmarks, gas hydrates, VHR seismic data, piezocone, numerical modelling, Niger Delta |
Abstract |
A review of recent literature shows that two geomorphologically different types of pockmarks, contribute to gas seepage at the seafloor. Type-1 pockmarks are defined as seafloor craters associated to fluid seepage and are the most classical type referred to as “pockmarks” in the literature. In contrast, Type-2 pockmarks reveal a complex seafloor morphology that may result from the formation/decomposition of gas hydrates in underlying sedimentary layers.Interpretation of very-high-resolution seismic data, sedimentological analyses and geotechnical measurements acquired from the Eastern Niger Submarine Delta reveal that Type-2 pockmarks are associated to the presence at depth of a conical body of massive gas hydrates. Based on acquired data, theoretical analysis and numerical modelling, it was possible to propose a novel geo-mechanical mechanism controlling the irregular seafloor deformations associated to Type-2 pockmark and to show that pockmark shapes and sizes are directly linked to the initial growth and distribution of sub-seafloor gas hydrates. The study illustrates the role of gas hydrates formation in the fracturation, deformation of the subsurface sediment and the formation of Type-2 pockmarks. |
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