Consulta: subjectFacets:"Oceanic crust"
Registros recuperados: 6
Data/hora: 26/07/2024 22:08:04

Behavior of Li and its isotopes during serpentinization of oceanic peridotites
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Decitre, S; Deloule, E; Reisberg, L; James, R; Agrinier, P; Mevel, C.
[1] Analyses of Li and Li isotopes in serpentinized peridotites have been performed using Thermo-Ionisation Mass Spectrometry (TIMS) and Secondary Ion Mass Spectrometry (SIMS) techniques on samples collected from the southwest Indian Ridge (SWIR). In the bulk samples, Li concentrations range from 0.6 to 8.2 ppm, while whole rock delta(6)Li values range from -2.9 to -14parts per thousand. In situ analyses display a greater range in both Li concentration (0.1-19.5 ppm) and Li isotopic composition ( -27 to +19parts per thousand), with the serpentinized portions having higher Li concentrations than the associated relict phases. These variations may reflect changes in Li partitioning and isotopic fractionation between serpentine and fluid with temperature and...
Tipo: Text
Palavras-chave: Lithium; Isotopes; Geochemical cycle; Oceanic crust; Serpentinization.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33403/31860.pdf

Constraints on the shallow velocity structure of the Lucky Strike Volcano, Mid-Atlantic Ridge, from downward continued multichannel streamer data
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Arnulf, A. F.; Harding, A. J.; Kent, G. M.; Singh, Shubpreet; Crawford, W. C.
The shallow velocity structure of the Lucky Strike segment of the Mid-Atlantic Ridge is investigated using seismic refraction and reflection techniques applied to downward continued multichannel streamer data. We present a three-dimensional velocity model beneath the Lucky Strike Volcano with unprecedented spatial resolutions of a few hundred meters. These new constraints reveal large lateral variations in P wave velocity structure beneath this feature. Throughout the study area, uppermost crustal velocities are significantly lower than those inferred from lower resolution ocean bottom seismometer studies, with the lowest values (1.8–2.2 km/s) found beneath the three central volcanic cones. Within the central volcano, distinct shallow units are mapped that...
Tipo: Text
Palavras-chave: Mid-Atlantic Ridge; Lucky Strike; Seismic refraction; Tomography; Oceanic crust; Downward continuation.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00185/29598/27965.pdf

Crustal structure of a super-slow spreading centre: a seismic refraction study of Mohns Ridge, 72 degrees N
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Klingelhofer, Frauke; Geli, Louis; Matias, Luis; Steinsland, N; Mohr, J.
A series of eight high-resolution seismic refraction profiles from the ultra-slow spreading (16 mm yr(-1) full spreading rate) Mohns Ridge in the Norwegian-Greenland Sea has been treated with modern inversion methods. The profiles were shot parallel to the ridge at an off-axis distance of 0-135 km corresponding to crustal ages of 0-22 Ma. The resulting models are constrained by synthetic seismograms and gravity modelling.The crustal thickness in all profiles is well below the global average for typical oceanic crust, and shows a high variability with a mean thickness of 4.0 +/- 0.5 km. This is mainly due to a very thin and variable lower crustal layer (Layer 3). Generally, the crust is thicker beneath basement highs and thinner beneath basins, implying...
Tipo: Text
Palavras-chave: Seismic refraction; Oceanic crust; Mohns Ridge; Mantle.
Ano: 2000
URL: https://archimer.ifremer.fr/doc/2000/publication-681.pdf

Deep crustal structure across a young passive margin from wide-angle and reflection seismic data (The SARDINIA Experiment) - I. Gulf of Lion's margin
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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

Heat flow in the Western Mediterranean: Thermal anomalies on the margins, the seafloor and the transfer zones
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Poort, Jeffrey; Lucazeau, Francis; Le Gal, Virginie; Dal Cin, Michaela; Leroux, Estelle; Bouzid, Abderrezak; Rabineau, Marina; Palomino, Désirée; Battani, Anne; Akhmanov G., Grigory; Ferrante G., Matilde; Gafurova R., Dina; Si Bachir, Roza; Koptev, Alexander; Tremblin, Maxime; Bellucci, Massimo; Pellen, Romain; Camerlenghi, Angelonghi; Migeon, Sebastien; Alonso, Belen; Ercilla, Gemma; Yelles-chaouche A., Karim; Khlystov M., Oleg.
The Western Mediterranean basin has been formed by Miocene back-arc extension and is underlain by a thin and young lithosphere. This young lithosphere is warm, as testified by an overall elevated offshore heat flow. Heat flow within the Western Mediterranean is, however, highly variable and existing data are unevenly distributed and poorly studied in the central part of the Liguro-Provençal and Algero-Balearic basins. This central part is floored by a young oceanic crust, bordered by different continental margins, cut by transform faults, and filled by up to 8 km of sediments. We present a total of 148 new heat flow data collected during the MedSalt and WestMedFlux cruises in 2015 and 2016 and aligned along seven regional profiles that show an important...
Tipo: Text
Palavras-chave: Heat flow; Western Mediterranean Sea; Liguro-Provencal basin; Algero-Balearic basin; Continental margins; Oceanic crust.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00588/70052/67992.pdf

Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, Pierre-marie; Ballu, V.
We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have identified a new on-axis site with diffuse flow, Ewan, and an active vent structure ∼1.2 km from the axis, Capelinhos. These sites are minor relative to the Main field, and our total heatflux estimate for all active sites (200–1200 MW) is only slightly higher than previously published estimates. We also identify fossil sites W of the main Lucky Strike field. A circular feature ∼200 m in diameter located on the flanks of a rifted off-axis central volcano is likely a large and inactive hydrothermal edifice, named Grunnus. We find no...
Tipo: Text
Palavras-chave: Hydrothermalism; Mid-ocean ridge; Heat flux; Faulting; Oceanic crust; Mid-Atlantic Ridge.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00281/39241/37812.pdf