Migration and venting of deep gases into the ocean through hydrate-choked chimneys offshore Korea

Abstract

Research Article| June 01, 2009 Migration and venting of deep gases into the ocean through hydrate-choked chimneys offshore Korea R.R. Haacke; R.R. Haacke 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada * Current address: Department of Earth Sciences, Royal Holloway University of London, TW20 0EX, UK; E-mail: [e-mail]. Search for other works by this author on: GSW Google Scholar R.D. Hyndman; R.D. Hyndman 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada Search for other works by this author on: GSW Google Scholar K-P. Park; K-P. Park 3Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea Search for other works by this author on: GSW Google Scholar D-G. Yoo; D-G. Yoo 3Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea Search for other works by this author on: GSW Google Scholar I. Stoian; I. Stoian 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada Search for other works by this author on: GSW Google Scholar U. Schmidt U. Schmidt 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information R.R. Haacke * Current address: Department of Earth Sciences, Royal Holloway University of London, TW20 0EX, UK; E-mail: [e-mail]. 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada R.D. Hyndman 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada K-P. Park 3Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea D-G. Yoo 3Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea I. Stoian 2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada U. Schmidt 1Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada Publisher: Geological Society of America Received: 28 Nov 2008 Revision Received: 23 Jan 2009 Accepted: 29 Jan 2009 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2009 Geological Society of America Geology (2009) 37 (6): 531–534. https://doi.org/10.1130/G25681A.1 Article history Received: 28 Nov 2008 Revision Received: 23 Jan 2009 Accepted: 29 Jan 2009 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation R.R. Haacke, R.D. Hyndman, K-P. Park, D-G. Yoo, I. Stoian, U. Schmidt; Migration and venting of deep gases into the ocean through hydrate-choked chimneys offshore Korea. Geology 2009;; 37 (6): 531–534. doi: https://doi.org/10.1130/G25681A.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 It has recently been recognized that, in addition to low concentrations of widespread natural gas hydrate associated with bottom-simulating seismic reflectors, highly concentrated hydrate can occur in local seafloor fluid venting structures. Such structures extend upward into the regional gas hydrate stability field and sometimes allow gases to escape into the overlying ocean. These hydrate-choked chimneys are especially prospective as an energy resource because they contain high hydrate concentrations. Furthermore, they may be one of the most important conduits into the ocean-atmosphere system for deep methane. We present an analysis of two-dimensional seismic reflection data from offshore Korea that give a complete picture of gas migrating from a deep source zone to feed hydrate-choked vent structures at the seafloor. The gases migrate upward through networks of fractures imaged as steep amplitude striations in both diffuse and concentrated distributions. We present an example of a high-flux gas vent fed through fracture swarms emanating from a 10–15-km-wide catchment zone of source gases residing 3–4 km below the seabed. The geological context and the inferred distribution of hydrate within this feature are consistent with recent models in which seabed gas venting is a consequence of elevated pore fluid salinities that are produced by a high flux of gases migrating independently of the pore water. In contrast, a nearby vent that is not plumbed into the same high-flux system appears to be dominated more by gas-rich liquids. We present these two vent structures as type cases for high- and lowflux fluid escape systems in the seabed. Furthermore, we suggest that since the amount of gas trapped as hydrate within the vents is small compared with the amount in the underlying reservoir, the greatest risk for increased methane input to the atmosphere associated with climate-driven oceanic warming is not the melting of hydrate, but an increase in the number of deep reservoirs able to vent gases through the seabed that occurs as the regional gas hydrate stability zone thins. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.