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Fluid flow regimes and growth of a giant pockmark

2013; Geological Society of America; Volume: 42; Issue: 1 Linguagem: Inglês

10.1130/g34801.1

1943-2682

Yann Marcon, Hélène Ondréas, Heiko Sahling, Gerhard Bohrmann, Karine Olu,

Geological formations and processes

Research Article| January 01, 2014 Fluid flow regimes and growth of a giant pockmark Yann Marcon; Yann Marcon 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Search for other works by this author on: GSW Google Scholar Hélène Ondréas; Hélène Ondréas 2IFREMER, Centre de Bretagne, REM/GM, 29280 Plouzané, France Search for other works by this author on: GSW Google Scholar Heiko Sahling; Heiko Sahling 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Search for other works by this author on: GSW Google Scholar Gerhard Bohrmann; Gerhard Bohrmann 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Search for other works by this author on: GSW Google Scholar Karine Olu Karine Olu 3IFREMER, Centre de Bretagne, REM/EEP, 29280 Plouzané, France Search for other works by this author on: GSW Google Scholar Author and Article Information Yann Marcon 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Hélène Ondréas 2IFREMER, Centre de Bretagne, REM/GM, 29280 Plouzané, France Heiko Sahling 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Gerhard Bohrmann 1MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany Karine Olu 3IFREMER, Centre de Bretagne, REM/EEP, 29280 Plouzané, France Publisher: Geological Society of America Received: 31 May 2013 Revision Received: 17 Sep 2013 Accepted: 20 Sep 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2014) 42 (1): 63–66. https://doi.org/10.1130/G34801.1 Article history Received: 31 May 2013 Revision Received: 17 Sep 2013 Accepted: 20 Sep 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Yann Marcon, Hélène Ondréas, Heiko Sahling, Gerhard Bohrmann, Karine Olu; Fluid flow regimes and growth of a giant pockmark. Geology 2014;; 42 (1): 63–66. doi: https://doi.org/10.1130/G34801.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Pockmarks are seafloor depressions commonly associated with fluid escape from the seabed and are believed to contribute noticeably to the transfer of methane into the ocean and ultimately into the atmosphere. They occur in many different areas and geological contexts, and vary greatly in size and shape. Nevertheless, the mechanisms of pockmark growth are still largely unclear. Still, seabed methane emissions contribute to the global carbon budget, and understanding such processes is critical to constrain future quantifications of seabed methane release at local and global scales. The giant Regab pockmark (9°42.6′ E, 5°47.8′ S), located at 3160 m water depth near the Congo deep-sea channel (offshore southwestern Africa), was investigated with state-of-the-art mapping devices mounted on IFREMER’s (French Research Institute for Exploitation of the Sea) remotely operated vehicle (ROV) Victor 6000. ROV-borne micro-bathymetry and backscatter data of the entire structure, a high-resolution photo-mosaic covering 105,000 m2 of the most active area, sidescan mapping of gas emissions, and maps of faunal distribution as well as of carbonate crust occurrence are combined to provide an unprecedented detailed view of a giant pockmark. All data sets suggest that the pockmark is composed of two very distinctive zones in terms of seepage intensity. We postulate that these zones are the surface expression of two fluid flow regimes in the subsurface: focused flow through a fractured medium and diffuse flow through a porous medium. We conclude that the growth of giant pockmarks is controlled by self-sealing processes and lateral spreading of rising fluids. In particular, partial redirection of fluids through fractures in the sediments can drive the pockmark growth in preferential directions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.