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Gas venting that bypasses the feather edge of marine hydrate, offshore Mauritania

Lookup NU author(s): Ang Li, Professor Richard DaviesORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2017 Elsevier Ltd Methane can be released from the vast marine hydrate reservoirs that surround continents into oceans and perhaps the atmosphere. But how these pathways work within the global carbon cycle now and during a warmer world is only partially understood. Here we use 3-D seismic data to identify what we interpret to be a gas venting system that bypasses the hydrate stability zone (HSZ) offshore of Mauritania. This venting is manifested by the presence of the acoustic wipe-out (AWO) across a densely faulted succession above a salt diapir and a set of morphological features including a substantial, ∼260 m wide and ∼32 m deep, pockmark at the seabed. The base of the HSZ is marked by a bottom simulating reflector (BSR) which deflects upwards above the diapir, rather than mimicking the seabed. We use a numerical modelling to show that this deflection is caused by the underlying salt diapir. It creates a trapping geometry for gas sealed by hydrate-clogged sediment. After entering the HSZ, some methane accumulated as hydrate in the levees of a buried canyon. Venting in this locality probably reduces the flux of gas to the landward limit of feather edge of hydrate, reducing the volume of gas that would be susceptible for release during a warmer world.

Publication metadata

Author(s): Li A, Davies RJ, Mathias SA, Yang J, Hobbs R, Wilson M

Publication type: Article

Publication status: Published

Journal: Marine and Petroleum Geology

Year: 2017

Volume: 88

Pages: 402-409

Online publication date: 24/08/2017

Acceptance date: 22/08/2017

Date deposited: 26/11/2018

ISSN (print): 0264-8172

Publisher: Elsevier Ltd


DOI: 10.1016/j.marpetgeo.2017.08.026


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