Role of tectonic stress in seepage evolution along the gas hydrate‐charged Vestnesa Ridge, Fram Strait

Plaza‐Faverola, Andreia; Bünz, Stefan; Johnson, Joel E.; Chand, Shyam; Knies, Jochen; Mienert, Jürgen; Franek, Peter

doi:10.1002/2014gl062474

Cited by 104 publications

(232 citation statements)

References 64 publications

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“…Also, other areas of the 3D seismic volume clearly indicate a relationship between Q values and the mapped fault system, e.g., to the northeast of fault 2 or between faults 2 and 4 (Figure 11a-11c). Together, these results suggest that the availability of free gas is one of the major factors in the accumulation of gas beneath the BSR and the formation of gas hydrates above it and that the availability of free gas clearly seems to be controlled by the structural setting supporting the findings of Plaza-Faverola et al (2015).…”

Section: Discussionsupporting

confidence: 57%

“…Fault systems mapped by Plaza-Faverola et al (2015) at approximately the BSR depth coincide strikingly with the boundaries of abrupt Q changes within layers three and four above and beneath the BSR, respectively (Figure 11a-11c). Changes in the Q within a layer are attributed with a variable pore fluid fill.…”

Section: Discussionmentioning

confidence: 72%

“…In a more recent study, Plaza-Faverola et al (2015) show that small-scale fault systems exist at the crest of the Vestnesa Ridge documenting a tectonic control of gas leakage. Fault systems mapped by Plaza-Faverola et al (2015) at approximately the BSR depth coincide strikingly with the boundaries of abrupt Q changes within layers three and four above and beneath the BSR, respectively (Figure 11a-11c).…”

Section: Discussionmentioning

confidence: 98%

“…A gas hydrate system and an associated free-gas zone exist along the Vestnesa Ridge (Hustoft et al, 2009;Petersen et al, 2010;Bünz et al, 2012;Plaza-Faverola et al, 2015). The system is restricted to the upper stratigraphic sequence (YP3) and has a series of gas chimneys and pockmarks associated along the full extent of the Vestnesa Ridge.…”

Section: Study Areamentioning

confidence: 99%

“…We used high-resolution P-cable (Planke et al, 2009;Petersen et al, 2010) 3D seismic data acquired in 2013 on board the R/V Helmer Hanssen (Plaza-Faverola et al, 2015). The system consists of 14 streamers towed parallel behind the ship.…”

Section: Datamentioning

confidence: 99%

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Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20-300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, is estimated from the seismic data set using the centroid frequency shift and spectral ratio (SR) methods. The centroid frequency shift method establishes a relationship between the change in the centroid frequency of an amplitude spectrum and the Q value of a medium. The SR method estimates the Q value of a medium by studying the differential decay of different frequencies. The broad bandwidth and short offset characteristics of the P-cable data set are useful to continuously map the Q for different layers throughout the 3D seismic volume. The centroid frequency shift method is found to be relatively more stable than the SR method. Q values estimated using these two methods are in concordance with each other. The Q data document attenuation anomalies in the layers in the gas hydrate stability zone above the bottom-simulating reflection (BSR) and in the free gas zone below. Changes in the attenuation anomalies correlate with small-scale fault systems in the Vestnesa Ridge suggesting a strong structural control on the distribution of free gas and gas hydrates in the region. We argued that high and spatially limited Q anomalies in the layer above the BSR indicate the presence of gas hydrates in marine sediments in this setting. Hence, our workflow to analyze Q using high-resolution P-cable 3D seismic data with a large bandwidth could be a potential technique to detect and directly map the distribution of gas hydrates in marine sediments.

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 98%

Section: Study Areamentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

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Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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Bivalve shell horizons in seafloor pockmarks of the last glacial‐interglacial transition: a thousand years of methane emissions in the Arctic Ocean

Ambrose

Panieri

Schneider

et al. 2015

Geochem Geophys Geosyst

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We studied discrete bivalve shell horizons in two gravity cores from seafloor pockmarks on the Vestnesa Ridge (∼1200 m water depth) and western Svalbard (79°00′ N, 06°55′ W) to provide insight into the temporal and spatial dynamics of seabed methane seeps. The shell beds, dominated by two genera of the family Vesicomyidae: Phreagena s.l. and Isorropodon sp., were 20–30 cm thick and centered at 250–400 cm deep in the cores. The carbon isotope composition of inorganic (δ13C from −13.02‰ to +2.36‰) and organic (δ13C from −29.28‰ to −21.33‰) shell material and a two‐end member mixing model indicate that these taxa derived between 8% and 43% of their nutrition from chemosynthetic bacteria. In addition, negative δ13C values for planktonic foraminifera (−6.7‰ to −3.1‰), concretions identified as methane‐derived authigenic carbonates, and pyrite‐encrusted fossil worm tubes at the shell horizons indicate a sustained paleo‐methane seep environment. Combining sedimentation rates with 14C ages for bivalve material from the shell horizons, we estimate the horizons persisted for about 1000 years between approximately 17,707 and 16,680 years B.P. (corrected). The seepage event over a 1000 year time interval was most likely associated with regional stress‐related faulting and the subsequent release of overpressurized fluids.

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Paleo‐methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard

Panieri

Graves

James

2016

Geochem Geophys Geosyst

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We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean warming may be fueling the destabilization of shallow methane hydrate. The d13 C values of benthic and planktonic foraminifera at the methane seep sites show distinct intervals with negative values (as low as 227.8&) that do not coincide with the present-day depth of the sulfate methane transition zone (SMTZ). These intervals are interpreted to record long-term fluctuations in methane release at the present-day landward limit of the gas hydrate stability zone (GHSZ). Shifts in the radiocarbon ages obtained from planktonic foraminifera toward older values are related to methane-derived authigenic carbonate overgrowths of the foraminiferal tests, and prevent us from establishing the chronology of seepage events. At shallower water depths, where seepage is not presently observed, no record of past methane seepage is recorded in foraminifera from sediments spanning the last 14 ka cal BP ( 14 C-AMS dating). d 13 C values of foraminiferal carbonate tests appear to be much more sensitive to methane seepage than other sediment parameters. By providing nucleation sites for authigenic carbonate precipitation, foraminifera thus record the position of even a transiently stable SMTZ, which is likely to be a characteristic of temporally variable methane fluxes.

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Role of tectonic stress in seepage evolution along the gas hydrate‐charged Vestnesa Ridge, Fram Strait

Cited by 104 publications

References 64 publications

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

Bivalve shell horizons in seafloor pockmarks of the last glacial‐interglacial transition: a thousand years of methane emissions in the Arctic Ocean

Paleo‐methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard

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