Spatial Changes in Gas Transport and Sediment Stiffness Influenced by Regional Stress: Observations From Piezometer Data Along Vestnesa Ridge, Eastern Fram Strait

Plaza‐Faverola, Andreia; Sultan, Nabil; Lucchi, Renata Giulia; Altuna, Naima El bani; Ramachandran, Hariharan; Singhroha, Sunny; Cooke, Frances; Vadakkepuliyambatta, Sunil; Ezat, Mohamed; Rasmussen, Tine L.

doi:10.1029/2022jb025868

Cited by 7 publications

(7 citation statements)

References 94 publications

(212 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To tie the metric core records to the time records of the Chirp data, the core records were converted to time using an average seismic velocity of 1,500 m/s, which was found suitable based on the sediment content and GEOTEK measurements (Magnetic susceptibility, wet bulk density, P-wave velocity and impedance; Supplementary Figure S6). The same average seismic velocity for the upper sediment column at Vestnesa Ridge was observed by other studies (e.g., Plaza-Faverola et al, 2023). CTD measurements have shown that sound velocity in the water column is on average 1,465 m/s in our study area (Figures 2A,C,D).…”

Section: Shallow Seismic Datasupporting

confidence: 90%

Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin

Rasmussen,

Nielsen

2024

Front. Earth Sci.

View full text Add to dashboard Cite

Vestnesa Ridge is built-up of thick contourites mainly deposited during the last ∼5 million years. Methane leaks from deep gas reservoirs creating pockmarks on its crest, and which have been the focus of numerous studies. Sedimentation patterns in relation to the pronounced changes in oceanography and climate of the last glacial-interglacial cycles and its possible impact of seepage of gas have rarely been studied. Here, we present a detailed history of contourite development covering the last ∼130,000 years with most details for the last 60,000 years. The study is based on 43 marine sediment cores and 1,430 km of shallow seismic lines covering the ridge including methane seep sites, with the purpose of reconstructing changes in depositional patterns in relation to paleoceanographical changes on glacial, interglacial, and millennial time scale in relation to activity of seepage of gas. The results show that thick Holocene deposits occurred below ∼1,250 m water depth in the western part of the ridge. Both in pockmarks at western and eastern Vestnesa Ridge, seepage decreased at ∼10–9 ka in the early Holocene. The fine Holocene mud likely reduced seepage to a slow diffusion of gas and microbial oxidation probably prevented escape from the seafloor. Results also showed that seepage of gas was highly variable during the glacial, and low to moderate during the cold Heinrich stadial H1 (19–15 ka) and Younger Dryas stadial (13–12 ka). Seepage reached a maximum during the deglaciation in the Bølling and Allerød interstadials 15–13 ka and early Holocene 12–10 ka. The deglaciation was a period of rapid climatic, oceanographic, and environmental changes. Seepage of gas varied closely with these events indicating that slower tectonic/isostatic movements probably played a minor role in these millennial scale rapid fluctuations in gas emission.

show abstract

Section: Shallow Seismic Datasupporting

confidence: 90%

Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin

Rasmussen,

Nielsen

2024

Front. Earth Sci.

View full text Add to dashboard Cite

show abstract

“…Nonetheless, even small fluctuations at the base of the GHSZ associated with the HS1 oceanic warming would have affected the already deformed sediments above the base of the GHSZ (Figure 9), as well as impacted near-surface sediments through further authigenic carbonate precipitation after gas hydrate dissolution and gas release (e.g., Sultan et al, 2020) (Figure 9). Additionally, as the system is critically stressed, small increases in free gas amounts beneath the base of the GHSZ would have been enough to trigger gas release through pre-existing fractures within the GHSZ along the Vestnesa Ridge (Ramachandran et al, 2022;Plaza-Faverola et al, 2023). This process reconciles the observation of small-scale buried pockmarks at highly deformed intervals (Figure 4, Figure 5, Figure 6).…”

Section: Gas Hydrate Dynamics During Glacial/ Interglacial Transitionssupporting

confidence: 52%

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

et al. 2023

View full text Add to dashboard Cite

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.

show abstract

“…In response to environmental changes, the re‐equilibration of the old BGHSZ from BSR2 to its current position suggests a decomposition of GH in a mixture of free gas and dissolved gas in the GH destabilization zone (GHDZ) (Sultan, 2007) (Figures 5(5)). Experimental studies show that grain size and connectivity between micro‐structures of the host sediment determine how gas is transported toward the surface (Jain & Juanes, 2009; Plaza‐Faverola et al., 2023). In the study zone, the very low permeability of the host sediment containing high amounts of clay‐silt (Ballas et al., 2018; Riedel et al., 2020) suggests that the fluid flow regime induced by hydrate dynamics is dominated by a gas diffusion process.…”

Section: Discussionmentioning

confidence: 99%

Slow Dynamics of Hydrate Systems Revealed by a Double BSR

Fabre,

Riboulot,

Loncke

et al. 2024

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Determining how gas hydrate distribution evolved along continental margins in the past is essential to understanding its evolution in the future. Moreover, hydrate decomposition has been linked to several catastrophic events, including some of the largest submarine landslides on Earth and the massive release of greenhouse gases into the ocean. Offshore Romania, the presence of a second bottom‐simulating reflector (BSR) provides an opportunity to gain valuable insights into hydrate dynamics since the Last Glacial Period (LGP). We conducted transient modeling of hydrate thermodynamic stability by merging in‐situ observations with indirect assessments of sea‐bottom temperature, thermal conductivity, salinity, sedimentation rate, and sea‐level variations. We reveal a strong correlation between the BSRs and the base of the Gas Hydrate Stability Zone (GHSZ) during both the present and LGP periods. The gradual evolution of the GHSZ over the past 34 ka presented here supports a conceptual model that excludes catastrophic environmental scenarios.

show abstract

Spatial Changes in Gas Transport and Sediment Stiffness Influenced by Regional Stress: Observations From Piezometer Data Along Vestnesa Ridge, Eastern Fram Strait

Abstract: Fine-grained marine sediments along continental slopes and rises are saturated with gas rich fluids. The mechanisms of gas transport from the source toward the seafloor influence the sediment geomechanical properties as well as gas hydrate accumulations and seepage dynamics (e.g.,

Cited by 7 publications

References 94 publications

Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin

Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin

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

Slow Dynamics of Hydrate Systems Revealed by a Double BSR

Contact Info

Product

Resources

About