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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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