Premiers résultats d'une étude géophysique sur le flanc nord des glissements de Storegga (Norvège)

Nouzé, Hervé; Contrucci, Isabelle; Foucher, Jean-Paul; Marsset, Bruno; Thomas, Y.; Thereau, Estelle; Normand, Alain; Drezen, E. Le; Didailler, Stéphane; Regnault, Jean-Pierre; Conte, Sandie Le; Guidart, Stéphanie; Lekens, W; Dean, S. M.; Throo, Alexandre

doi:10.1016/j.crte.2004.06.005

Cited by 9 publications

(6 citation statements)

References 11 publications

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“…The "Hydratech"-project of the European Union 5 th Framework program collected high-resolution 3D-seismic data during a cruise, led by Ifremer, to the mid-Norwegian margin in 2002 ( Fig. 1) (Nouzé et al, 2004). The 3D-seismic dataset cover an area of ~28 km 2 located in water depths between 1050 m and 1150 m. The bin size (~6 m) of the 3D-dataset and the dominant frequency (~80 Hz) provides an appreciable horizontal and vertical resolution compared to conventional industry 3D-seismic data.…”

Section: Seismic Data and Methodsmentioning

confidence: 99%

High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin

et al. 2007

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Seismic attribute analysis and interpretation of high-resolution 3D-and 2D-seismic data reveal focussed fluid flow processes through the gas hydrate stability zone (GHSZ) at the northern flank of the giant Storegga Slide. Diffusive fluid migration predominantly starts from a widespread polygonal fault system in fine-grained sediments of the Miocene Kai Formation. The overlying 600-700 m thick Plio-Pleistocene Naust Formation shows spatially related soft-sediment deformation and overlying fluid conduits. A low relief antiform structure connects to an overlying 250 m high, 300 m wide and 3 km elongated columnar zone, where seismic signatures suggest self-enhanced permeability, i.e. natural hydraulic fracturing. "Push-down" effects create an elongated depression caused by increased gas accumulations where a cluster of vertical cylindrical acoustic pipe structures originates. These pipe clusters pierce the GHSZ and indicate focussed fluid flow pathways originating from potentially overpressured sediments. High seismic reflection amplitudes at the seafloor above the pipe structures may indicate pockmarks with authigenic carbonates and/or gas hydrates. The observed objects and seismic features presented are not stand-alone indicators for fluid flow, but a joint perspective illustrates that they are vertically tied together providing new insights to the effects of focussed fluid flow.

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Section: Seismic Data and Methodsmentioning

confidence: 99%

High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin

et al. 2007

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“…The Vøring Basin off mid-Norway is well known for widespread fluid migration leading to the development of numerous seafloor pockmarks (Evans et al, 1996;Bünz et al, 2003;Nouzé et al, 2004). Previous studies, based on exploration 2D and 3D seismic data in the area, have shown that fluid pipes ascend from different source zones, e.g.…”

Section: Introductionmentioning

confidence: 98%

Anatomy of a fluid pipe in the Norway Basin: Initiation, propagation and 3D shape

et al. 2012

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“…The CNE sites were identified previous to this study at the seafloor and in depth using conventional bathymetric mapping and seismics, respectively. These data that we can qualify as 'vintage' were acquired during the Hydratech marine expedition (Nouzé et al, 2002;Nouzé et al, 2004) with a few of the unpublished seismic lines presented here.…”

Section: Introductionmentioning

confidence: 80%

“…High-resolution 2D 120-channel seismic reflection (acquired with two mini-GI guns) and hull-mounted sub-bottom profiler (1.8-5.2 kHz) surveys were conducted during the Hydratech expedition onboard the R/V Le Suroît in 2002 (Nouzé et al, 2002;Nouzé et al, 2004). Three unpublished processed lines crossing the studied Nyegga area (Figure 2A) are shown in Figure 2B, Figure 2C and Figure 3C, including stacked and migrated sections for the multichannel seismics.…”

Section: Methodsmentioning

confidence: 99%

“…Most of these data are unpublished. The geophysical data were mainly acquired during the Hydratech (Nouzé et al, 2002;Nouzé et al, 2004) and Vicking (Nouzé et al, 2007) expeditions with however a few additional data acquired during the TTR16 expedition (Akhmetzhanov et al, 2008). The near-bottom investigation was conducted during the Vicking cruise with the Ifremer Victor ROV, and included biological and geological observations and sampling of the seabed.…”

Section: Introductionmentioning

confidence: 99%

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Methane-flow system within the Nyegga pockmark field, offshore mid-Norway

Dupré,

Foucher,

Pierre

et al. 2023

Front. Earth Sci.

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We investigated fluid seepage within the Nyegga pockmark field (600–900 m water depths) off mid-Norway from Remotely Operated Vehicle dives at the so-called CNE sites (CNE01 to CNE17). The seafloor morphology of some of these features corresponds to pockmarks and adjacent ridges, with the latter being the focus of present seepage activity. These structures are underlain by chimneys above a gas-charged zone with, in some cases, a substantial body of hydrate-invaded sediment (down to 1.3 s in two-way travel time at CNE03). Present-day methane-rich fluid seepage through the seabed is indicated by chemosynthetic fauna, in particular Siboglinidae polychaetes (Oligobrachia haakonmobiensis webbi and Sclerolinum contortum), microbial mats and associated Rissoidae gastropod (Alvania sp.) grazers, and confirmed by measured in situ bottom-water methane anomalies, up to 2,130 nL/L. No free-gas bubble emissions were observed or acoustically identified. The presence of authigenic carbonates reveals past seepage with very low δ13C values (down to −58‰) indicating that the major source of carbon was methane carried by the venting fluids. The ages of major periods of methane venting are provided by vesicomyid bivalve shells (Isorropodon nyeggaensis) present in two sedimentary layers, 14,930 and 15,500 14C yr BP (ca. 17,238 and 17,952 cal yr BP), respectively, corresponding to the time of Melt Water Pulse IA. The seafloor morphology and pattern of seepage -chemosynthetic fauna and microbial mat distribution and dissolved methane concentration-are remarkably heterogeneous. Pore-water chemistry profiles in a gravity core taken only 40 m from major seepage sites indicate no seepage and anaerobic methane oxidation at a sub-bottom depth of about 2 m. Present-day seepage from the studied pockmark-chimney fluid-flow system charged with gas hydrate is dominated by the advection of methane solution in pore water. Some of this methane could result from the dissolution of hydrate in the chimney, most of which would have formed during an earlier period (post-LGM times) of history of the chimney, when it was venting free gas. However, the presence of free gas beneath this chimney is probably why the water entering the chimney is already saturated with methane and the process of hydrate formation in the chimney continues today.

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Premiers résultats d'une étude géophysique sur le flanc nord des glissements de Storegga (Norvège)

Cited by 9 publications

References 11 publications

High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin

High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin

Anatomy of a fluid pipe in the Norway Basin: Initiation, propagation and 3D shape

Methane-flow system within the Nyegga pockmark field, offshore mid-Norway

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