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Registros recuperados: 16
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Blind submarine seismic deconvolution for long source wavelets ArchiMer
Nsiri, Benayad; Chonavel, Thierry; Boucher, Jean; Nouze, Herve.
In seismic deconvolution, blind approaches must be considered in situations where reflectivity sequence, source wavelet signal, and noise power level are unknown. In the presence of long source wavelets, strong interference among the reflectors contributions makes the wavelet estimation and deconvolution more complicated. In this paper, we solve this problem in a two-step approach. First, we estimate a moving average (MA) truncated version of the wavelet by means of a stochastic expectation-maximization (SEM) algorithm. Then, we use Prony's method to improve the wavelet estimation accuracy by fitting an autoregressive moving average (ARMA) model with the initial truncated wavelet. Moreover, a solution to the wavelet initialization problem in the SEM...
Tipo: Text Palavras-chave: Bernoulli Gaussian BG process; Blind deconvolution; Gibbs sampler; Maximum likelihood ML; Maximum posterior mode MPM; Monte Carlo Markov chains MCMCs methods; Prony algorithm; Seismic deconvolution; Stochastic expectation maximization SEM.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00000/11030/8978.pdf
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Changes in seabed morphology, mud temperature and free gas venting at the Håkon Mosby mud volcano, offshore northern Norway, over the time period 2003-2006 ArchiMer
Foucher, Jean-paul; Dupre, Stephanie; Scalabrin, Carla; Feseker, Tomas; Harmegnies, Francois; Nouze, Herve.
The Håkon Mosby mud volcano is a 1.5-km-diameter geological structure located on the Southwest Barents Sea slope at a water depth of 1,270 m. High-definition seabed mapping of the mud volcano has been carried out in 2003 and 2006. A comparative analysis of the bathymetry and backscatter maps produced from the two surveys shows subtle morphological changes over the entire crater of the mud volcano, interpreted to be the consequence of mud eruption events. Mud temperature measurements point to a persistently warm mud at shallow depth in the crater. This is explained by upward fluid advection, rather than conductive cooling of mud flows. The small-scale spatial variability in the temperature distribution may be related to mud outflows or changes in the fluid...
Tipo: Text Palavras-chave: Sw barents sea; Cold seep ecosystems; Fluid flow; Methane; Sediment; Onshore; Fluxes; Margin; Water.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00004/11527/10261.pdf
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Crustal structure of the basin and ridge system west of New Caledonia (southwest Pacific) from wide-angle and reflection seismic data. ArchiMer
Klingelhoefer, Frauke; Lafoy, Y; Collot, Julien; Cosquer, Emmanuel; Geli, Louis; Nouze, Herve; Vially, R.
[1] During the Zoneco 11 marine geophysical survey (September 2004), two deep reflection seismic profiles recorded by ocean bottom seismometers were acquired in the offshore domain west of New Caledonia. The northern profile crosses the New Caledonia Basin, the Fairway Ridge, the Fairway Basin, and the Lord Howe Rise. The southern profile crosses the Norfolk Rise south of New Caledonia, the New Caledonia Basin, the Fairway Ridge and Basin, and ends at the foot of Lord Howe Rise. On the northern profile the Lord Howe Rise has a crustal thickness of 23 km and exhibits seismic velocities and velocity gradients characteristic of continental crust. The crust thins to 12-15 km in the neighboring Fairway Basin, which is interpreted to be of thinned continental...
Tipo: Text Palavras-chave: Crustal structure; SW Pacific; Wide angle seismic.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3543.pdf
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Crustal structure of the SW-Moroccan margin from wide-angle and reflection seismic data (the DAKHLA experiment) Part A: Wide-angle seismic models ArchiMer
Klingelhoefer, Frauke; Labails, Cinthia; Cosquer, Emmanuel; Rouzo, Stephane; Geli, Louis; Aslanian, Daniel; Olivet, Jean-louis; Sahabi, M.; Nouze, Herve; Unternehr, P..
A total 1500 km of seismic reflection and wide-angle profiles were acquired off the southern Moroccan margin during the DAKHLA cruise, a joint project of Ifremer, the Universities of Brest, El Jadida and Lisbon and Total. The shots along two profiles parallel to the margin and two profiles perpendicular to the margin were also recorded by ocean bottom seismometers (OBS). The profiles perpendicular to the margin were additionally extended on land using 14 stations on the northern profile and 11 stations on the southern profile. Modelling of the reflection and wide-angle seismic data reveals a 10 km deep sedimentary basin including two high velocity carbonate layers. Lateral crustal thinning is observed from a 27 km thick crystalline continental crust to a 7...
Tipo: Text Palavras-chave: Ocean continent transition; Keyword wide angle seismic; Southern Moroccan margin.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6410.pdf
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Deep crustal structure across a young passive margin from wide-angle and reflection seismic data (The SARDINIA Experiment) - I. Gulf of Lion's margin ArchiMer
Moulin, Maryline; Klingelhoefer, Frauke; Afilhado, Alexandra; Aslanian, Daniel; Schnurle, Philippe; Nouze, Herve; Rabineau, Marina; Beslier, Marie-odile; Feld, Aurelie.
The conjugate margins system of the Gulf of Lion and West Sardinia (GLWS) represents a unique natural laboratory for addressing fundamental questions about rifting due to its landlocked situation, its youth, its thick sedimentary layers, including prominent palaeo-marker such as the MSC event, and the amount of available data and multidisciplinary studies. The main goals of the SARDINIA experiment, were to (i) investigate the deep structure of the entire system within the two conjugate margins: the Gulf of Lion and West Sardinia, (ii) characterize the nature of the crust, and (iii) define the geometry of the basin and provide important constrains on its genesis. This paper presents the results of P-wave velocity modelling on three coincident near-vertical...
Tipo: Text Palavras-chave: Marge continentale passive; Structure crustale; Réfraction; Golfe du Lion; Croûte océanique; Domaine transitionnel; Continental passive margin; Crustal structure; Wide-angle seismic; Gulf of Lion; Oceanic crust; Transitional domain.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00283/39422/38269.pdf
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Erosion and sedimentation as processes controlling the BSR-derived heat flow on the Eastern Nankai margin ArchiMer
Martin, V; Henry, P; Nouze, Herve; Noble, M; Ashi, J; Pascal, G.
In 2000, a 3D MCS survey was carried out on the Eastern Nankai Trough. A strong and widespread bottom-simulating reflector (BSR) was observed and mapped after a preserved amplitude 3D prestack migration of the seismic data. We use this BSR to calculate a heat flow map over the 3D survey area. This map presents some high and low heat flow areas, that cannot be correlated to known active wedge faults and previously observed fluid venting sites. Since the heat flow anomalies are not correlated to known major faults or fluid venting sites, large fluid circulation is not likely to explain the varying BSR-derived heat flow distribution. In order to explain this heat flow distribution quantitatively, we calculate the rates of erosion and sedimentation that are...
Tipo: Text Palavras-chave: Eastern Nankai margin; Surface processes; Heat flow; Bottom simulating reflector.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-509.pdf
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Estimation of gas hydrate concentration from multi-component seismic data at sites on the continental margins of NW Svalbard and the Storegga region of Norway ArchiMer
Westbrook, G; Chand, S; Rossi, G; Long, C; Bunz, S; Camerlenghi, A; Carcione, J; Dean, S; Foucher, Jean-paul; Flueh, E; Gei, D; Haacke, R; Madrussani, G; Mienert, Jurgen; Minshull, T; Nouze, Herve; Peacock, S; Reston, T; Vanneste, M; Zillmer, M.
High-resolution seismic experiments, employing arrays of closely spaced, four-component ocean-bottom seismic recorders, were conducted at a site off western Svalbard and a site on the northern margin of the Storegga slide, off Norway to investigate how well seismic data can be used to determine the concentration of methane hydrate beneath the seabed. Data from P-waves and from S-waves generated by P-S conversion on reflection were inverted for P- and S-wave velocity (V-p and V-s), using 3D travel-time tomography, 2D ray-tracing inversion and 1D waveform inversion. At the NW Svalbard site, positive V-p anomalies above a sea-bottom-simulating reflector (BSR) indicate the presence of gas hydrate. A zone containing free gas up to 150-m thick, lying immediately...
Tipo: Text Palavras-chave: Continental margin; Hydrate concentration; Seismic velocity; S wave; P wave.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6122.pdf
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First results of a geophysical survey on the northern flank of the Storegga. slides (Norway). ArchiMer
Nouze, Herve; Contrucci, Isabelle; Foucher, Jean-paul; Marsset, Bruno; Thomas, Yannick; Thereau, Estelle; Normand, Alain; Le Drezen, Eliane; Didailler, Stephane; Regnault, Jean-pierre; Le Conte, Sandie; Guidart, Stéphanie; Lekens, Win; Dean, Simon; Throo, Alexandre.
The Storegga slides, off Norway, are among the largest submarine slides ever known on a continental slope. The HYDRATECH cruise on N/O Le Suro (i) over capt aimed at a high-resolution survey of an area at the northern boundary of the slides. This survey images in great detail the bottom simulating reflector (BSR) extent and properties, the various fluid escape structures and the sediment deformations. The combination and the quality of the data help to understand the still poorly constrained relationships between fluid escapes, gas hydrates and slope stability in the survey area.
Tipo: Text Palavras-chave: Slope stability; Fluid escapes; Gas hydrates; Storegga.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-511.pdf
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Geological constraints on the evolution of the Angolan margin based on reflection and refraction seismic data (ZaïAngo project) ArchiMer
Moulin, Maryline; Aslanian, Daniel; Olivet, Jean-louis; Contrucci, Isabelle; Matias, Luis; Geli, Louis; Klingelhoefer, Frauke; Nouze, Herve; Rehault, Jean Pierre; Unternehr, Patrick.
Deep penetration multichannel reflection and Ocean Bottom Seismometer wide-angle seismic data from the CongoAngola margin were collected in 2000 during the ZaïAngo cruise. These data help constrain the deep structure of the continental margin, the geometry of the pre-salt sediment layers and the geometry of the Aptian salt layer. Dating the deposition of the salt relative to the chronology of the margin formation is an issue of fundamental importance for reconstructing the evolution of the margin and for the understanding of the crustal thinning processes. The data show that the crust thins abruptly, from a 3040 km thickness to less than 10 km, over a lateral distance of less than 50 km. The transitional domain is a 180-km-wide basin. The pre-salt sediment...
Tipo: Text Palavras-chave: Deep seismic reflection and refraction; Sub salt imaging; Transitional domain; Crustal structure; Non volcanic passive continental margin.
Ano: 2005 URL: https://archimer.ifremer.fr/doc/2005/publication-349.pdf
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Geophysical characterization of bottom simulating reflectors in the Fairway Basin (off New Caledonia, Southwest Pacific), based on high resolution seismic profiles and heat flow data ArchiMer
Nouze, Herve; Cosquer, Emmanuel; Collot, Julien; Foucher, Jean-paul; Klingelhoefer, Frauke; Lafoy, Yves; Geli, Louis.
High-resolution reflection and refraction seismic data were collected in 2004 to investigate, in further detail than allowed by pre-existing low resolution seismic data, the nature of a Bottom Simulating Reflector (BSR) that extends over a broad area of the Fairway Basin, a rifted, continental structure located on the eastern flank of the Lord Howe Rise, to the southwest of New Caledonia. Two main reflectors are documented: the shallower (RN) mimics the seafloor and has a negative polarity while the deeper (RP) does not always mimic the seafloor and has a positive polarity. Using the existing regional seismic lines, we can show that reflector RN can be continuously followed up to DSDP 208 drill hole site. Reflector RP is discontinuous and cannot be traced...
Tipo: Text Palavras-chave: Stratigraphy; Gas hydrates; Geophysics; Southwest Pacific; Fairway Basin; BSR.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-7321.pdf
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High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin ArchiMer
Hustoft, S; Mienert, Jurgen; Bunz, S; Nouze, Herve.
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...
Tipo: Text Palavras-chave: Acoustic pipes and pockmarks; Feeding of methane to hydrate deposits; Hydraulic fracturing; Polygonal faulting; Norwegian margin.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-4077.pdf
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Large gas hydrate accumulations on the eastern Nankai Trough inferred from new high-resolution 2-D seismic data ArchiMer
Nouze, Herve; Henry, P; Noble, M; Martin, V; Pascal, G.
Previous studies have revealed the presence of a widespread Bottom Simulating Reflector (BSR) on the eastern Nankai slope, as well as the occurrence of enigmatic high amplitude reflections that extend well above the BSR. New high-resolution 2-D seismic data were collected on the eastern Nankai slope, during the French-Japanese SFJ cruise in year 2000 and AVA analyses of the enigmatic reflectors are conducted. At the studied location, these analyses suggest that high amplitude anomalies above the BSR delineate the top of gas hydrate rich sediments. Several tens % of the sediment porosity would be filled with gas hydrates between the BSR and a sharp boundary 30 to 60 m above. To account for these observations, we propose that an invasion by free gas of the...
Tipo: Text Palavras-chave: Zone; Model; Ridge; Methane gas; Marine sediments.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-510.pdf
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Multiple bottom-simulating reflections in the Black Sea: Potential proxies of past climate conditions ArchiMer
Popescu, Irina; De Batist, Marc; Lericolais, Gilles; Nouze, Herve; Poort, Jeffrey; Panin, Nicolae; Versteeg, Wim; Gillet, Herve.
A previously unknown pattern of multiple bottom-simulating reflections (BSRs) occurs on high-resolution reflection seismic data in the Danube deep-sea fan, associated with acoustic features indicating free gas. Our study provides evidence that this pattern is developed in relation with the architecture of distinct channel-levee systems of the Danube fan. Channel-levee systems hosting multiple BSRs act as relatively sealed gas-bearing systems whose top is situated above the base of the gas hydrate stability zone (BGHSZ). Inside these systems, free gas accumulates below the BGHSZ under a combined lithological, structural and stratigraphical control. The uppermost BSR marks the current equilibrium BGHSZ, for a gas composition of more than 99% methane....
Tipo: Text Palavras-chave: Black Sea; Deep sea fan; Seismic data; Gas; Gas hydrates; Bottom simulating reflections.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1210.pdf
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Seistec seismic profiles: A tool to differentiate gas signatures ArchiMer
Baltzer, Agnès; Tessier, Bernadette; Nouze, Herve; Bates, R; Moore, C; Menier, D.
The presence of gas is a common feature in many seismic sections. However, the origin of the gas is often difficult to determine. Recently acquired very high resolution seismic profiles using an IKB Seistec boomer provide useful insight to the understanding of the gas origins in a range of environmental settings including sea lochs and coastal lagoons. The gas features are described both from a qualitative point of view through their acoustic facies, and quantitatively through the associated seismic signal (polarisation, amplitude). Acoustic facies include acoustic turbidity, gas "curtains" and "blankets" as well as "white fringes" and "black shadows". All the features encountered have been related to specific gas nature generated by different sources...
Tipo: Text Palavras-chave: Signal amplitude; Signal polarisation; Gas; Acoustic facies; Seistec profiles.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-835.pdf
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Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific ArchiMer
Collot, Julien; Geli, Louis; Lafoy, Y; Vially, R; Cluzel, D; Klingelhoefer, Frauke; Nouze, Herve.
New, high-quality multichannel seismic reflection data from the western New Caledonia offshore domain allow for the first time the direct, continuous connection of seismic reflectors between the Deep Sea Drilling Project 208 drill hole on the Lord Howe Rise and the New Caledonia Basin. A novel seismic interpretation is hence proposed for the northern New Caledonia Basin stratigraphy, which places the Eocene/Oligocene unconformity deeper than previously thought and revisits the actual thickness of the pre-Oligocene sequences. A causal link is proposed between the obduction of the South Loyalty Basin over New Caledonia (NC) and the tectonic history of the northern New Caledonia Basin. Here it is suggested that as the South Loyalty Basin was being obducted...
Tipo: Text Palavras-chave: New Caledonia; Seismics; Obduction.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4782.pdf
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Victor 6000: New high resolution tools for deep sea research. « Module de Mesures en Route » ArchiMer
Simeoni, Patrick; Sarrazin, Jozee; Nouze, Herve; Sarradin, Pierre-marie; Ondreas, Helene; Scalabrin, Carla; Sinquin, Jean-marc.
This paper describes the new survey module (called "Module de Mesures en Route"), of the Remotely Operated Vehicle (ROV) Victor 6000 and presents the first results obtained during two scientific cruises held during the summer of 2006 (Viking and Momareto).
Tipo: Text
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3596.pdf
Registros recuperados: 16
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