Irregular BSR: evidence of an on-going reequilibrium of a gas hydrate system

Date 2020
Author(s) Colin FlorentORCID1, Ker StephanORCID1, Marsset BrunoORCID1, Thomas Yannick1
Affiliation(s) 1 : IFREMER, REM-GM, Centre de Brest, BP 70, PLouzané 29280, France
DOI 10.17882/74866
Publisher SEANOE
Keyword(s) deep-towed, SYSIF, seismic, Black Sea, hydrates, methane, gas, BSR, dissociation, very high resolution, multichannel, transient, high-resolution
Abstract

Gas hydrate (GH) systems constitute methane sinks sensitive to environmental changes such as pressure, temperature or salinity. It remains a matter of debate whether the large GH system of the Black Sea has achieved a steady state since the last glacial maximum (LGM). We report on an irregular free gas distribution occurring in specific sediment layers marking an irregular bottom-simulating reflector (BSR). This anomalous free gas distribution revealed by very high resolution seismic images, acquired by a deep-towed multichannel seismic system, might be an evidence of an on-going migration of the base of the GH stability zone (GHSZ). We show that the reequilibrium is not occurring homogeneously as overpressure from hydrates dissociation slows their decomposition in specific sedimentary layers. The Black Sea example highlights that dissociation and the associated methane released in the water column or even in the atmosphere could be largely delayed by overpressure accumulation.

Licence CC-BY-NC
Data
File Size Format Processing Access
Profile Bla1-7 (HR seismic - BLASON cruise) 31 MB SEGY Processed data Open access
Profile PL01PR12 (VHR seismic - SYSIF - GHASS cruise) 59 MB SEGY Processed data Open access
Profile PL01PR13 (VHR seismic - SYSIF - GHASS cruise) 59 MB SEGY Processed data Open access
Profile PL03PR07 (VHR seismic - SYSIF - GHASS cruise) 58 MB SEGY Processed data Open access
Profile PL03PR11 (VHR seismic - SYSIF - GHASS cruise) 51 MB SEGY Processed data Open access
Profile HR31a (HR seismic - GHASS cruise) 56 MB SEGY Processed data Open access
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How to cite 

Colin Florent, Ker Stephan, Marsset Bruno, Thomas Yannick (2020). Irregular BSR: evidence of an on-going reequilibrium of a gas hydrate system. SEANOE. https://doi.org/10.17882/74866