Sedimentary deformation relating to episodic seepage in the last 1.2 million years: a multi-scale seismic study from the Vestnesa Ridge, eastern Fram Strait

Type Article
Date 2023-05
Language English
Author(s) Cooke Frances1, Plaza-Faverola Andreia1, Bunz Stefan1, Sultan NabilORCID2, Ramachandran Hariharan3, Bedle Heather4, Patton Henry1, Singhroha Sunny1, Knies Jochen5
Affiliation(s) 1 : CAGE—Centre for Arctic Gas Hydrate, Environment and Climate, UiT (The Arctic University of Norway), The Arctic University of Norway, Tromsø, Norway
2 : Geo-Ocean, UMR6538, Ifremer, CNRS, UBO, UBS, Plouzané, France
3 : Institute of GeoEnergy Engineering, Heriot-Watt University, Edinburgh, United Kingdom
4 : School of Geosciences, The University of Oklahoma, Norman, OK, United States
5 : NGU—Geological Survey of Norway, Trondheim, Norway
Source Frontiers In Earth Science (2296-6463) (frontiers media), 2023-05 , Vol. 11 , P. 1188737 (17p.)
DOI 10.3389/feart.2023.1188737
WOS© Times Cited 1
Keyword(s) sediment fracturing, episodic seepage, high-resolution seismic attributes, glacial dynamics, Fram Strait
Abstract

Seafloor hydrocarbon seepage is a natural fluid release process that occurs worldwide on continental shelves, slopes, and in deep oceanic basins. The Vestnesa sedimentary ridge in the eastern Fram Strait hosts a deep-water gas hydrate system that became charged with hydrocarbons ∼2.7 Ma and has experienced episodic seepage along the entire ridge until a few thousand years ago, when seepage activity apparently ceased in the west but persisted in the east. Although it has been documented that faults and fractures play a key role in feeding the seeps with thermogenic gases, the mechanisms controlling seepage periodicity remain poorly understood. Here we integrate high-resolution P-cable 3D seismic and Chirp data to investigate the spatial and temporal evolution of high-resolution fractures and fluid flow features in the west of the Vestnesa Ridge. We characterize sediment deformation using a fracture density seismic attribute workflow revealing two highly deformed stratigraphic intervals and associated small-scale pockmarks (<20 m diameter). Chronostratigraphic constraints from the region show that these two highly deformed intervals are influenced by at least three major climatic and oceanic events during the last 1.2 million years: the Mid-Pleistocene Transition (∼1.25–0.7 Ma), the penultimate deglaciation (∼130 ka) and the last deglaciation (Heinrich Stadial 1: ∼16 ka). These periods of deformation appear associated with seismic anomalies potentially correlated with buried methane-derived authigenic carbonate and have been sensitive to shifts in the boundary of the free gas-gas hydrate interface. Our results show shifts (up to ∼30 m) in the depth of the base of the gas hydrate stability zone (GHSZ) associated with major changes in ocean bottom water temperatures. This ocean-driven effect on the base of the GHSZ since the Last Glacial Maximum coincides with the already highly deformed Mid-Pleistocene Transition sedimentary interval and likely enhanced deformation and gas leakage along the ridge. Our results have implications for understanding how glacial cycles impact fracture formation and associated seepage activity.

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Cooke Frances, Plaza-Faverola Andreia, Bunz Stefan, Sultan Nabil, Ramachandran Hariharan, Bedle Heather, Patton Henry, Singhroha Sunny, Knies Jochen (2023). Sedimentary deformation relating to episodic seepage in the last 1.2 million years: a multi-scale seismic study from the Vestnesa Ridge, eastern Fram Strait. Frontiers In Earth Science, 11, 1188737 (17p.). Publisher's official version : https://doi.org/10.3389/feart.2023.1188737 , Open Access version : https://archimer.ifremer.fr/doc/00839/95130/