Consulta: subjectFacets:"Pockmarks"
Registros recuperados: 12
Data/hora: 01/06/2024 17:31:56

New evidence of perfect overlapping of Haploops and pockmarks field: Is it a coincidence?
Provedor de dados: 5
Autores: Champilou, Jean-baptiste; Baltzer, Agnes; Murat, Anne; Reynaud, Marine; Maillet, Grégoire M.; Nardelli, Maria Pia; Metzger, Édouard.
In the shallow waters of the Bay of Concarneau (South Brittany, France), previous studies reported a dense settlement of the species Haploops (tube-dwelling bioengineer amphipod) that perfectly overlaps a field of pockmarks. A possible mechanistic link may therefore exist between the Haploops colonies and the shallow pockmarks. To test this hypothesis, interferometry sonar and sub-bottom profiler chirp data were acquired in two new areas located in the marine estuary of the Loire River, “La Lambarde” and “Le Croisic”. The new sites share the same sedimentary and geological characteristics as those found in the Bay of Concarneau. The three sites are similarly located in shallow and muddy environments above a faulted Middle Eocene formation that is incised...
Tipo: Text
Palavras-chave: Shallow waters; South Brittany (France); Geophysics; Pockmarks; Haploops.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00502/61324/64896.pdf

Space-time evolution of a large field of pockmarks in the Bay of Concarneau (NW Brittany)
Provedor de dados: 5
Autores: Baltzer, Agnes; Reynaud, Marine; Ehrhold, Axel; Fournier, Jerome; Cordier, Celine; Clouet, Helene.
About a decade ago, a large field of pockmarks, covering an overall area of 36 km(2) was discovered in water depths of &lt; 30m in the central part of the Bay of Concarneau (Southern Brittany, France). This field, composed of features from 5 m to 35 m in diameter and &lt; 1 m in depth, is characterized by unusual high densities of pockmarks, up to 5840 per square kilometre. Geophysical data correlated with sedimentary samples acquired in 2005 and 2009 show that pockmarks and their immediate surroundings are associated with dense tubes benches cover, built by a filter-feeding amphipod: Haploops nirae, forming original benthic communities. Two complementary surveys were carried out in April 2011 (Pock and Ploops) and April 2014 (Pock and Tide), on the...
Tipo: Text
Palavras-chave: Géophysique; Marée; Failles; Gaz; Geophysics; Pockmarks; Tide; Turbidity; Gas; Chimneys pipes; Concarneau.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00410/52107/52938.pdf

Slope morphologies offshore Dakhla (SW-Moroccan margin)
Provedor de dados: 5
Autores: Benabdellouahed, Massinissa; Baltzer, Agnes; Rabineau, Marina; Aslanian, Daniel; Sahabi, Mohamed; Germond, Fabien; Loubrieu, Benoit; Biari, Youssef.
This study explores a portion of the West African margin at the junction between two well- known segments offshore Dakhla and offshore Mauritania with destructional architecture characterized by giant slides. In between these two segments, the Dakhla segment has historically been described as a constructional section. During an oceanographic Dakhla cruise (2002), high resolution seismic data, swath bathymetry and imagery were acquired around latitude 23° N, offshore Dakhla,. This new data set reveals the existence of varied and complex morphologies on the continental slope, interpreted as a "shallot-shaped" canyon, seafloor depressions or pockmarks, ridges and scarps. These morphologies are interpreted as clues of sedimentary transfers and rupture...
Tipo: Text
Palavras-chave: African margin; Bathymetry; Seismic interpretation; Pockmarks; Ridges; Scarps.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00286/39736/38214.pdf

Sea-level change and free gas occurrence influencing a submarine landslide and pockmark formation and distribution in deepwater Nigeria
Provedor de dados: 5
Autores: Riboulot, Vincent; Cattaneo, Antonio; Sultan, Nabil; Garziglia, Sebastien; Ker, Stephan; Imbert, Patrice; Voisset, Michel.
A series of pockmarks observed at the seabed matches well the perimeter of a large submarine landslide, called NG1, located on the outer shelf and continental slope of the Eastern Gulf of Guinea. NG1 extends over 200 km2, is covered by a 120-m thick sedimentary layer which tapers downslope, and has an internal structure clearly identified in 3D seismic data consisting of three adjacent units on the upper continental slope. The pockmarks above NG1 have a diameter of several tens of meters and reveal distinct origins: (1) linked to &gt;500 m deep fluid reservoirs, (2) rooted in NG1 internal discontinuities between NG1 units, and (3) well above NG1, superficially rooted in a regional conformity (D40), which marks the lowest sea level of the Marine Isotope...
Tipo: Text
Palavras-chave: Pockmarks; Fluid seepage; Submarine landslide; Sea-level changes; Piezocone; Niger Delta.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00159/27031/31906.pdf

Evidences of early to late fluid migration from an upper Miocene turbiditic channel revealed by 3D seismic coupled to geochemical sampling within seafloor pockmarks, Lower Congo Basin
Provedor de dados: 5
Autores: Gay, A; Lopez, M; Cochonat, Pierre; Levache, D; Sermondadaz, G; Seranne, M.
Using high quality 3D seismic data within the Lower Congo Basin (LCB), we have identified pockmarks that are aligned above the sinuous belt of a buried turbiditic palaeo-channel, 1000 m beneath the seafloor. Geochemical analyses on cores (GC traces), taken in the centre of four of these pockmarks along this channel, show no clear evidence for migrated oil. But, some features of the GC traces, including elevated baselines (UCM &gt; 34 mu g/g) and a broad molecular weight range of n-alkanes with little odd-even preference, may be interpreted as indicating the presence of thermogenic hydrocarbons in the cores.   Seismic profiles show that these pockmarks developed above two-main features representative of pore fluid escape during early compaction: (1) closely...
Tipo: Text
Palavras-chave: Pipes; Seismic chimneys; Polygonal faults; Fluid migration; Turbiditic channels; Pockmarks.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1673.pdf

Ecologie de la faune associée aux émissions de fluides froids de Méditerranée orientale profonde
Provedor de dados: 5
Autores: Ritt, Benedicte.
The major objectives of this thesis were to study the structure, functioning and dynamics of different faunal assemblages associated with cold seep ecosystems in the eastern Mediterranean Sea. We focused our study on three main sites: the Marmara Sea, the Mediterranean ridge and the Nile deep sea fan. This thesis aims at determining the environmental signature of Mediterranean sites and the characteristics of the associated fauna at European and global scales. The specific objectives were to (1) determine the composition, diversity, density, biomass of invertebrate assemblages, (2) characterize biogeochemical conditions within different microhabitats in the vicinity of organisms, (3) to define the trophic relationships amongst seep fauna using stable...
Tipo: Text
Palavras-chave: Emissions de fluides froids; Volcans de boue; Pockmarks; Méditerranée orientale; Faune benthique; Conditions environnementales; Indices de diversité; Cold seeps; Eastern Mediterranean; Mud volcanoes; Pockmarks; Benthic fauna; Environmental conditions; Diversity indices.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00020/13138/10178.pdf

U-Th isotope constraints on gas hydrate and pockmark dynamics at the Niger delta margin
Provedor de dados: 5
Autores: Bayon, Germain; Henderson, Gideon M.; Etoubleau, Joel; Caprais, Jean-claude; Ruffine, Livio; Marsset, Tania; Dennielou, Bernard; Cauquil, Eric; Voisset, Michel; Sultan, Nabil.
The application of uranium-thorium dating methods to authigenic carbonates provides unique constraints on the temporal evolution of methane seeps at ocean margins. In this study, we report U-Th isotope measurements for carbonate breccias collected from within a hydrate-bearing pockmark located at the Niger Delta margin. These concretions were extracted from a carbonate-rich layer in the upper two meters of a sediment core (N2-KS-44; ~ 1200 m water depth), well above the present-day sulphate-methane transition zone (about 3 m depth) and the presence of gas hydrates in the sediment. The stratigraphy of core N2-KS-44 was established by tuning its downcore Al/Ti profile to a well-dated nearby reference core, and carbonate 230Th/U ages were calculated using...
Tipo: Text
Palavras-chave: Gas hydrates; Pockmarks; U-series; Authigenic carbonates; Niger delta.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00286/39708/41518.pdf

Initiation of gas-hydrate pockmark in deep-water Nigeria: Geo-mechanical analysis and modelling
Provedor de dados: 5
Autores: Riboulot, Vincent; Sultan, Nabil; Imbert, P.; Ker, Stephan.
A review of recent literature shows that two geomorphologically different types of pockmarks, contribute to gas seepage at the seafloor. Type-1 pockmarks are defined as seafloor craters associated to fluid seepage and are the most classical type referred to as “pockmarks” in the literature. In contrast, Type-2 pockmarks reveal a complex seafloor morphology that may result from the formation/decomposition of gas hydrates in underlying sedimentary layers.  Interpretation of very-high-resolution seismic data, sedimentological analyses and geotechnical measurements acquired from the Eastern Niger Submarine Delta reveal that Type-2 pockmarks are associated to the presence at depth of a conical body of massive gas hydrates. Based on acquired data, theoretical...
Tipo: Text
Palavras-chave: Pockmarks; Gas hydrates; VHR seismic data; Piezocone; Numerical modelling; Niger Delta.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00301/41215/40643.pdf

Microbial methane oxidation and sulfate reduction at cold seeps of the deep Eastern Mediterranean Sea
Provedor de dados: 5
Autores: Omoregie, Enoma O.; Niemann, Helge; Mastalerz, Vincent; De Lange, Gert J.; Stadnitskaia, Alina; Mascle, Jean; Foucher, Jean-paul; Boetius, Antje.
The Eastern Mediterranean hosts a variety of active cold seep systems, such as gas chimneys, mud volcanoes and pockmarks, in water depths of 500 to 3200 m. As part of the NAUTINIL expedition in 2003, the sediments of cold seeps on the Nile Deep Sea Fan (NDSF) were sampled for the first time for biogeochemical and microbiological analyses. Here we compare rates of the anaerobic oxidation of methane (AOM) and sulfate reduction (SR) as well as the microbial community structure of a variety of cold seep systems including mud volcanoes, pockmarks and brine seeps. Our results revealed strong differences in microbial activity among the different seep systems of the Eastern, Central and Western provinces of the NDSF, as well as the Olimpi field (Central...
Tipo: Text
Palavras-chave: Methane oxidation; Sulfate reduction; Archaea; Cold seeps; Mud volcano; Pockmarks; Nile Deep Sea Fan.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00000/11087/7910.pdf

Isolated seafloor pockmarks linked to BSRs, fluid chimneys, polygonal faults and stacked Oligocene-Miocene turbiditic palaeochannels in the Lower Congo Basin
Provedor de dados: 5
Autores: Gay, Aurelien; Lopez, M; Cochonat, Pierre; Seranne, M; Levache, D; Sermondadaz, G.
Based on high-resolution 3D seismic data sets, we document the subsurface reservoir architecture and organization of a portion of the Oligocene-Miocene stratigraphy within the Congo Basin, offshore southwestern Africa. Within the 3D seismic volume, we have identified four levels of turbiditic palaeochannels, which are separated by low-amplitude continuous reflectors interpreted as hemipelagic sediments. Geochemical analyses on sediment samples taken within overlying seafloor pockmarks reveal the presence of thermogenic gases and oils, suggesting that deep-seated fluids have migrated through both the channel deposits and the impermeable layers between them, forming a conduit to the surface. Deep thermogenic fluids produced within Cretaceous source rocks are...
Tipo: Text
Palavras-chave: Polygonal faults; BSR; Fluid chimneys; Pipes; Hydrates; Turbiditic palaeochannels; Pockmarks; Fluid migration.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1111.pdf

The Enya mounds: a lost mound-drift competition
Provedor de dados: 5
Autores: Van Rooij, D.; Huvenne, V. A. I.; Blamart, D.; Henriet, J.-p.; Wheeler, A.; De Haas, H.
The genesis and evolution of cold-water coral banks along the Northeastern Atlantic margin is known to be influenced by several factors, among which the palaeotopography and nature of the coral settling surface, the presence of bottom currents and sediment supply. In this paper, a case study is presented of the Enya mound cluster, located in the southernmost tip of the Belgica mound province, west of Ireland. Below this mound cluster, seismic stratigraphy revealed a yet unmapped local unconformity RD1b, being part of a composite erosion event (RD1). As such, from the Late Miocene to Late Pliocene, at least two erosional events have incised the margin, ending with the final RD1a "moundbase" unconformity, acting as a base for the Enya mounds. During the...
Tipo: Text
Palavras-chave: Cold-water coral banks; Contourite drift; Pockmarks; Unconformity; Seismic stratigraphy.
Ano: 2009
URL: https://archimer.ifremer.fr/doc/00219/33075/31550.pdf

Mass-transport deposits and fluid venting in a transform margin setting, the eastern Demerara Plateau (French Guiana)
Provedor de dados: 5
Autores: Pattier, France; Loncke, L.; Gaullier, V.; Basile, C.; Maillard, Alexandre; Imbert, Patrice; Roest, Walter; Vendeville, B. C.; Patriat, Martin; Loubrieu, Benoit.
The eastern Demerara Plateau offshore French Guiana was surveyed in 2003 during the GUYAPLAC cruise (multibeam bathymetry and acoustic imagery, 6-channel seismic reflection and 3.5 kHz echo-sounding). The data show the "post-transform" Cenozoic that the series located on the outer part of the plateau (below c. 2000 m) contain at least twelve stacked mass transport deposits (MTDs) that have recorded a history of large-scale slope failure, as well as two main normal fault sets that provide possible pathways for upward fluid migration through the series, reaching at high as the uppermost MTDs. Seabed data show that the area above the failures is characterized by circular-to-elongate (slope-parallel) depressions interpreted as fluid seeps (pockmarks), some of...
Tipo: Text
Palavras-chave: Fluid ascent; Pockmarks; MTDs; Transform margin; Demerara Plateau.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00157/26850/25316.pdf