Consulta: subjectFacets:"Mid-ocean ridges"
Registros recuperados: 9
Data/hora: 09/06/2024 10:43:38

Tectonics at the axis of the very slow spreading Southwest Indian Ridge: Insights from TOBI side-scan sonar imagery
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gomez, O; Briais, Anne; Sauter, D; Mendel, V.
We present the analysis of the deformation in the axial valley of two contrasted regions of the very slow spreading Southwest Indian Ridge based on side-scan sonar images. Our objective is to investigate how the obliquity is accommodated along the system. We show that the robust magmatic segments have axial valleys and major faults subperpendicular to spreading. The other sections show fault populations with various degrees of obliquity, often arranged in left-stepping echelons, accommodating part of the strike-slip deformation. Side-scan sonar reveals the presence of a corrugated surface near 59 degrees E interpreted to be an incipient detachment fault. We show that the large width of the SWIR oblique sections, and the difference in tectonic style between...
Tipo: Text
Palavras-chave: Mid-ocean ridges; Side-scan sonar; Tectonics; Discontinuities.
Ano: 2006
URL: https://archimer.ifremer.fr/doc/00234/34567/33236.pdf

Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cannat, Mathilde; Sauter, Daniel; Bezos, Antoine; Meyzen, Christine; Humler, Eric; Le Rigoleur, Marion.
We use bathymetry, gravimetry, and basalt composition to examine the relationship between spreading rate, spreading obliquity, and the melt supply at the ultraslow spreading Southwest Indian Ridge (SWIR). We find that at regional scales (more than 200 km), melt supply reflects variations in mantle melting that are primarily controlled by large-scale heterogeneities in mantle temperature and/or composition. Focusing on adjacent SWIR regions with contrasted obliquity, we find that the effect of obliquity on melt production is significant (about 1.5 km less melt produced for a decrease of 7 mm/a to 4 mm/a in effective spreading rates, ESR) but not enough to produce near-amagmatic spreading in the most oblique regions of the ridge, unless associated with an...
Tipo: Text
Palavras-chave: Mid-ocean ridges; Melt supply; Mantle melting; Magmatic segmentation.
Ano: 2008
URL: https://archimer.ifremer.fr/doc/00237/34860/33204.pdf

Cartographie haute résolution des champs hydrothermaux de la ride sud du bassin de Guaymas
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Ondreas, Helene; Scalabrin, Carla; Fouquet, Yves; Godfroy, Anne.
Insights into the factors controlling fluid circulation through the crust and the nature of fluid venting at the seafloor are first steps in understanding their effect on ocean properties and climate change. New data on the seafloor morphology, sub-surface sedimentary stratification, and water column of the sedimented Southern Trough hydrothermal field (Guaymas basin) were acquired during the BIG cruise in 2010. These data provide accurate and high-resolution information on the geological context of the vents, on the distribution of acoustic anomalies in the water column, and on the possible nature of the fluid generating these echoes. More than 40 hydrothermal edifices were observed. The southern zone of the study area hosts hydrothermal sites that differ...
Tipo: Text
Palavras-chave: Mid-ocean ridges; Sedimented ridge; Hydrothermal systems; Fluid migration; Water-column acoustic images; Guaymas basin.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00436/54775/56229.pdf

The Mid‐Atlantic Ridge Near 13°20′N: High‐Resolution Magnetic and Bathymetry Imaging
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Searle, R. C.; Macleod, C. J.; Peirce, C.; Reston, T. J.
We describe detailed magnetic and bathymetric studies around 13 degrees N on the Mid-Atlantic Ridge, a site of extensive detachment faulting. Inversion of closely spaced sea surface magnetic anomalies reveals a disorganized pattern of magnetization, with anomalies younger than anomaly 2 being poorly delineated. The Brunhes anomaly width is highly variable but averages similar to 60% of that predicted for the regional spreading rate. It is often split, both along and across axis, by apparently reversely magnetized crust. Gaps in the Brunhes anomaly match gaps in the neovolcanic zone inferred from acoustic backscatter. A strong negative magnetization is associated with the oceanic core complex (OCC) at 13 degrees 2'N (OCC1320) and is inferred to arise from...
Tipo: Text
Palavras-chave: Mid-ocean ridges; Oceanic core complexes; Magnetic anomalies; Microtopography.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00499/61031/64436.pdf

High-resolution bathymetry reveals contrasting landslide activity shaping the walls of the Mid-Atlantic Ridge axial valley
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cannat, Mathilde; Mangeney, Anne; Ondreas, Helene; Fouquet, Yves; Normand, Alain.
Axial valleys are found along most slow-spreading mid-ocean ridges and are one of the most prominent topographic features on Earth. In this paper, we present the first deep-tow swath bathymetry for the axial valley walls of the Mid-Atlantic Ridge. These data allow us to analyze axial valley wall morphology with a very high resolution (0.5 to 1 m compared to 50 m for shipboard multibeam bathymetry), revealing the role played by landslides. Slow-spreading ridge axial valleys also commonly expose mantle-derived serpentinized peridotites in the footwalls of large offset normal faults (detachments). In our map of the Ashadze area (lat. 13 degrees N), ultramafic outcrops have an average slope of 18 degrees and behave as sliding deformable rock masses, with...
Tipo: Text
Palavras-chave: Landslides; Detachment faults; Basalts; Mid-ocean ridges; Serpentinized peridotites.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00284/39516/38004.pdf

Wavelet analysis of deep-tow magnetic profiles: Modeling the magnetic layer thickness over oceanic ridges
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pouliquen, G; Sailhac, P.
The interpretation of marine magnetic anomalies usually consists either in determining the magnetization distribution assuming the source geometry and magnetization direction or in determining the magnetic layer thickness assuming the magnetization direction and intensity. In this paper, we introduce a new technique that allows modeling of the thickness of the magnetic source layer with very few a priori assumptions about the magnetization: the magnetic layer is assumed to be made of a series of bodies, each having a constant unknown magnetization and an unknown size. This technique is based upon the application of the continuous wavelet transform recently introduced for the interpretation of potential field data as a multipole decomposition. We present...
Tipo: Text
Palavras-chave: Wavelet transform; Multipole decomposition; Magnetic anomalies; Source layer thickness; Mid-ocean ridges.
Ano: 2003
URL: https://archimer.ifremer.fr/doc/00224/33551/32040.pdf

Contrasted hydrothermal activity along the South-East Indian Ridge (130°E-140°E): From crustal to ultramafic circulation
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Boulart, Cedric; Briais, Anne; Chavagnac, Valerie; Revillon, Sidonie; Ceuleneer, Georges; Donval, Jean-pierre; Guyader, Vivien; Barrere, Fabienne; Ferreira, Nicolas; Hanan, Barry; Hemond, Christophe; Macleod, Sarah; Maia, Marcia; Maillard, Agnes; Merkuryev, Sergey; Park, Sung-hyun; Ruellan, Etienne; Schohn, Alexandre; Watson, Sally; Yang, Yun-seok.
Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 130°-140°E section of the poorly-known South-East Indian Ridge (SEIR) from the Australia-Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH4 anomalies in the water column above a serpentinite massif, which unambiguously testify for ultramafic-related fluid flow. This is the first time that such circulation is observed on an intermediate-spreading ridge. The ridge axis itself is characterized by numerous off-axis volcanoes, suggesting a high magma supply. The water column survey indicates the presence of at least ten distinct hydrothermal plumes along the axis. The CH4:Mn ratios...
Tipo: Text
Palavras-chave: Hydrothermal plumes; Mid-ocean ridges; South-East Indian Ridge.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00387/49821/50400.pdf

Mobility and immobility of mid-ocean ridges and their implications to mantle dynamics
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Masalu, D.C.P.
In the past two decades, the mobility of mid-ocean ridges relative to the mantle (absolute migration) has been correlated with major observable features, such as spreading asymmetry and asymmetry in the abundance of seamounts. The mobility of mid-ocean ridges is also thought to be an important factor that influences the diversity of ridge-crest basalts. However, this mobility has not yet been defined and mapped. The absolute migration of global mid-ocean ridges since 85 Ma has been computed and mapped. Global mid-ocean ridges have migrated extensively at varying velocities during that period. Presently, the fast-migrating ridges are the Pacific- Antarctic, Central Indian Ridge, Southeast Indian Ridge, Juan de Fuca, Pacific-Nazca, Antarctic-Nazca, and the...
Tipo: Journal Contribution
Palavras-chave: Geology; Mid-ocean ridges.
Ano: 2002
URL: http://hdl.handle.net/1834/734

Absolute migration and the evolution of the Rodriguez Triple Junction since 75 Ma
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Masalu, D.C.P.
The Rodriguez Triple Junction (RTJ) is a junction connecting three mid-ocean ridges in the Indian Ocean: the Southwest Indian Ridge (SWIR), the Central Indian Ridge (CIR) and the Southeast Indian Ridge (SEIR). The evolution of the RTJ has been studied extensively for the past 10 Ma and the triple junction is believed to be largely a ridge-ridge-ridge (RRR) triple junction. However, due to the scarcity of data its configuration prior to that period is poorly understood. The migration of the RTJ in the hotspot reference frame, for the past 75 million years has been mapped, by reconstructing its traces on the three plates (African, Antarctic and Indian) to their former positions. The results show that the RTJ has migrated northeasterly at velocities varying...
Tipo: Journal Contribution
Palavras-chave: Mid-ocean ridges.
Ano: 2002
URL: http://hdl.handle.net/1834/740