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| Moulin, Maryline; Aslanian, Daniel; Unternehr, Patrick. |
| The opening of the Equatorial and South Atlantic Oceans is still a matter of debate, particularly as concerns the locations of the intraplate deformation. We propose here a critical review of the kinematic models published since Bullard et al., 1965, based on a series of constraints: new interpretation of the magnetic anomalies, seafloor isochrons, flow lines, fracture zones, continental and oceanic homologous structures and radiometric dating of igneous rocks. All of these models present numerous unexplained misfits (gaps, overlaps and misalignments). We present here a new evolution of the Equatorial and South Atlantic Ocean from the tightest reconstruction to Chron C34. This new model confirms the hypothesis of a northward propagation of the South... |
| Tipo: Text |
Palavras-chave: Initial kinematic reconstruction; South and Equatorial Atlantic Oceans; Intraplate deformation; Magnetic anomalies. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00000/11160/7883.pdf |
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| Sibuet, Jean-claude; Srivastava, Shiri; Manatschal, Gianreto. |
| [1] Transitional zones located between Iberia and North America formed during continental rifting and mostly consist of exhumed mantle. In this study we show that ages of exhumed mantle at Ocean Drilling Program (ODP) sites 1068 and 1070 in the Iberia Abyssal Plain and site 1277 in the Newfoundland Basin are similar to ages determined from magnetic lineations created by serpentinization during mantle exhumation. On the basis of paleomagnetic and geological data and a comparison with a fossil ocean-continent transition in the Alps, we envisage a first episode of mantle serpentinization during which a strong component of magnetization was acquired followed by a second episode occurring at the contact with cold seawater, and which only affects the upper tens... |
| Tipo: Text |
Palavras-chave: Magnetic anomalies; Newfoundland Iberia rift; Exhumed mantle. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3015.pdf |
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| Herzer, R. H.; Barker, D. H. N.; Roest, Walter; Mortimer, N.. |
| A tectonic model of the evolution of the northern half of the South Fiji Basin, including the Minerva Triple Junction and Cook Fracture Zone, is developed from regional gravity, multibeam bathymetry, and a new interpretation of magnetic anomalies pinned to radiometric dates of oceanic crust in the basin. The geometry and age of a portion of the Minerva Triple Junction and the Cook-Minerva spreading center (the connection from the triple junction to the Cook Fracture Zone, which accommodated coeval opening of the Norfolk Basin), are resolved with multibeam bathymetry and magnetics. The South Fiji Basin opened from about 34 to 15 Ma in an anticlockwise sweep about an Euler pole located at the northern end of the present Lau Ridge. This rotation and a rigidly... |
| Tipo: Text |
Palavras-chave: South Fiji Basin; Back-arc basin evolution; Multibeam bathymetry; Magnetic anomalies; Gravity model; New Zealand plate boundary. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00030/14112/11362.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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| Louvel, Veronique; Dyment, Jerome; Sibuet, Jean-claude. |
| The deep seismic reflection profile Western Approaches Margin (WAM) cuts across the Goban Spur continental margin, located southwest of Ireland. This non-volcanic margin is characterized by a few tilted blocks parallel to the margin. A volcanic sill has been emplaced on the westernmost tilted block. The shape of the eastern part of this sill is known from seismic data, but neither seismic nor gravity data allow a precise determination of the extent and shape of the volcanic body at depth. Forward modelling and inversion of magnetic data constrain the shape of this volcanic sill and the location of the ocean-continent transition. The volcanic body thickens towards the ocean, and seems to be in direct contact with the oceanic crust. In the contact zone, the... |
| Tipo: Text |
Palavras-chave: Continental margin; Goban Spur; Magnetic anomalies; Ocean-continent boundary. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44777/44601.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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| Szitkar, Florent; Dyment, Jerome; Choi, Yujin; Fouquet, Yves. |
| High-resolution magnetic surveys acquired near the seafloor show that active basalt-hosted hydrothermal sites are associated with zones of lower magnetization. This observation may reflect the thermal demagnetization of a hot hydrothermal zone, the alteration of basalt affected by hydrothermal circulation, and/or the presence of thick, nonmagnetic hydrothermal deposits. In order to discriminate among these inferences, we acquired vector magnetic data 50 m above inactive hydrothermal site Krasnov using the Remotely Operated Vehicle (ROV) Victor. This deep hydrothermal site, located 7 km east of the Mid-Atlantic Ridge (MAR) axis at 16°38′N, is dissected by major normal faults and shows no evidence of recent hydrothermal activity. It is therefore a perfect... |
| Tipo: Text |
Palavras-chave: Magnetic anomalies; Hydrothermalism; Alteration; Modeling. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29915/28375.pdf |
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