Deep-towed High Resolution multichannel seismic imaging

Marsset, Bruno; Menut, E.; Ker, Stéphan; Thomas, Y.; Regnault, Jean-Pierre; Léon, Pierre; Martinossi, H.; Artzner, Laurent; Chenot, Damien; Dentrecolas, S.; Spychalski, B.; Mellier, G.; Sultan, Nabil

doi:10.1016/j.dsr.2014.07.013

Cited by 28 publications

(9 citation statements)

References 14 publications

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“…Two‐dimensional very high resolution deep‐towed seismic profiles were acquired with the Ifremer SYstème SIsmique Fond system (Marsset et al, ). SYstème SIsmique Fond is a deep‐towed seismic device hosting a Janus‐Helmholtz transducer emitting a linear chirp signal in the frequency bandwidth (220–1050 Hz) and a 52‐channel seismic streamer with a hydrophone spacing of 2 m, both towed between 50 and 100 m above the seafloor.…”

Section: Methodsmentioning

confidence: 99%

“…SYstème SIsmique Fond is a deep‐towed seismic device hosting a Janus‐Helmholtz transducer emitting a linear chirp signal in the frequency bandwidth (220–1050 Hz) and a 52‐channel seismic streamer with a hydrophone spacing of 2 m, both towed between 50 and 100 m above the seafloor. After careful processing of the positioning, seismic signature deconvolution enables to obtain a 1‐m vertical resolution while the prestack depth imaging procedure specifically developed for the particular geometry of the deep‐towed acquisition (Marsset et al, , ) allows to reach a 2‐m lateral resolution.…”

Section: Methodsmentioning

confidence: 99%

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Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Ker

Thomas

Riboulot

et al. 2019

Geochem Geophys Geosyst

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A comprehensive characterization of gas hydrate system offshore the western Black Sea was performed through an integrated analysis of geophysical data. We detected the bottom‐simulating reflector (BSR), which marks, in this area, the base of gas hydrate stability. The observed BSR depth does not fit the theoretical steady state base of gas hydrate stability zone (BGHSZ). We show that the disparity between the BSR and predicted BGHSZ is the result of a transient state of the hydrate system due to the ongoing reequilibrium since the Last Glacial Maximum. When gas hydrates are brought outside the stability zone due to changes in temperature and sea level, their dissociation generates an increase in interstitial pore pressure. This process is favorable to the recrystallization of gas hydrates and delays the upward migration of the hydrate stability zone explaining the anomalously deep BSR. The BSR depth, which is commonly used to derive geothermal gradient values by assuming steady state conditions, is used here to derive the maximum excess pore pressure at the BGHSZ. Derived excess pore pressure values of 1–2 MPa are probably the result of the low permeability of hydrate‐bearing sediments. Higher pore pressure values derived at the location of a fault system could cause hydrofracturing enabling the free gas to cross the gas hydrate stability zone and emerge at the seafloor, forming the flares observed in close vicinity to where the shallow gas hydrates were sampled.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Ker

Thomas

Riboulot

et al. 2019

Geochem Geophys Geosyst

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“…The 2D very high resolution seismic data were acquired with the Sysif system 58 , 59 . SYSIF is a deep-towed seismic device hosting a piezoelectric transducer (seismic source) and a 120 m long seismic streamer (52 traces, 2 m).…”

Section: Methodsmentioning

confidence: 99%

Freshwater lake to salt-water sea causing widespread hydrate dissociation in the Black Sea

et al. 2018

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Gas hydrates, a solid established by water and gas molecules, are widespread along the continental margins of the world. Their dynamics have mainly been regarded through the lens of temperature-pressure conditions. A fluctuation in one of these parameters may cause destabilization of gas hydrate-bearing sediments below the seafloor with implications in ocean acidification and eventually in global warming. Here we show throughout an example of the Black Sea, the world’s most isolated sea, evidence that extensive gas hydrate dissociation may occur in the future due to recent salinity changes of the sea water. Recent and forthcoming salt diffusion within the sediment will destabilize gas hydrates by reducing the extension and thickness of their thermodynamic stability zone in a region covering at least 2800 square kilometers which focus seepages at the observed sites. We suspect this process to occur in other world regions (e.g., Caspian Sea, Sea of Marmara).

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“…Two-dimensional deep-towed multichannel very high-resolution seismic data ( Fig. 6) were acquired for the first time in the GoL during PRISME2 campaign (Cattaneo, 2013a) using Ifremer's in-house acquisition system SYSIF (SYstème SIsmique de Fond, Ker et al 2010;Marsset et al 2014). It consists of an open-cavity acoustic source and a specially developed streamer that is towed at a constant altitude above the seafloor (50-100 m).…”

Section: Geophysical Datamentioning

confidence: 99%

Integrated geophysical, sedimentological and geotechnical investigation of submarine landslides in the Gulf of Lions (Western Mediterranean)

Badhani

Cattaneo

Collico³

et al. 2020

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The Gulf of Lions presents recurring mass-transport deposits (MTDs) within the Plio-Quaternary sediments, suggesting a long history of mass movements. The two large, surficial MTDs are located on the eastern and western levee of the Rhone canyon over an area exceeding 6000 km2 and volumes exceeding 100 km3. Both MTDs were emplaced 21 ka ago (peak of the Last Glacial Maximum), suggesting a common trigger. Here, we present a multidisciplinary high-resolution geophysical, sedimentological and in-situ geotechnical study of the source and deposit areas of both MTDs to characterize distinct expressions of sediment deformation as well as their spatial and chronological distributions. We show the internal structure of mass movements and resulting MTDs with unprecedented details that were previously represented in the conventional seismic data as transparent and chaotic facies. The combination of multidisciplinary approaches shows new insights into the nature of basal surfaces of the slope failures. In particular, we show that the basal surfaces of the failures consist of clay-rich material contrasting with the overlying turbiditic deposits, suggesting that a strong lithological heterogeneity exists within the strata. We suggest that this change in lithology between clay-rich sediments and turbiditic sequences most likely controls the localization of weak layers and landslide basal surfaces.

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Deep-towed High Resolution multichannel seismic imaging

Abstract: Highlights ► Perform deep towed High Resolution multichannel seismic imaging. ► Design of pressure-resistant digital hydrophones. ► Monitor the streamer deformation with pitch, roll, and heading sensors.

Cited by 28 publications

References 14 publications

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Freshwater lake to salt-water sea causing widespread hydrate dissociation in the Black Sea

Integrated geophysical, sedimentological and geotechnical investigation of submarine landslides in the Gulf of Lions (Western Mediterranean)

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