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| Lallemand, S; Collot, J-y; Pelletier, B; Rangin, C; Cadet, J-p. |
| This paper presents some of the implications of oceanic asperities in subduction zones, based on examples gathered during the world circumnavigation of R/V Jean Charcot . The study of these examples provides a new overview of active margin modelling in response to asperity subduction. It is concluded that both erosion and accretion may be governed by the oceanic plate even though frontal tectonic erosion is better documented because it is accessible to conventional surveys. Most of the time, erosion is due to the relaxation of the arc slope in the wake of asperity/subduction. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37957/36038.pdf |
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| Pelletier, B; Dupont, J. |
| The Louisville Ridge, a hotspot chain, obliquely subducts at the Tonga-Kermadec consuming plate boundary (Southwest Pacific). This ridge has swept the Tonga Trench and the ridge-trench junction point is rapidly (at least 10 cm per year) migrating southward along the Kermadec trench. Results from a comparative morphological study between the Kermadec and Tonga margins, and from the Seapso 5 seabeam survey around the ridge-trench junction consider the effects of the subduction of an oblique ridge on an active margin. Underplating of material scraped and pushed in the front of the ridge could be responsible for the high-standing position of the Tonga platform in the prolongation of the Kermadec active volcanic line. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37904/35985.pdf |
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| Recy, J; Pelletier, B; Charvis, P; Gerard, M; Monjaret, M-c; Maillet, P. |
| The New Hebrides back-arc troughs are restricted to the southern and northern rear of the arc. Lack of trough in the central part is related to the compression induced by the collision of the d'Entrecasteaux ridge and the New Hebrides arc. The southern troughs are 50-60 km wide and are composed of one or two grabens striking N130-140 degree , while the northern troughs extend over 70 km wide and are composed of a succession of N-S trending grabens, horsts and half-grabens. Although the location and the main trend (N150 degree ) of the troughs indicate that they are largely guided by the subduction, the direction of extension (N40-45 degree ) is clearly oblique to the volcanic line and thus does not seem related to the subduction process. Formation of the... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37950/36031.pdf |
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| Pontoise, B; Pelletier, B. |
| Seapso V cruise was conducted in January 1986. It started on the 13th from Nuku'Alfa (Kingdom of Tonga) and ended in Papeete (French-Polynesia) on the 28th. The main objectives of this cruise were to gather new data on two well defined problems in order to: 1-understand the tectonic processes of the subduction of an aseismic ridge (the Louisville ridge) and 2-Test of a unique method of detecting, locating and evaluating uncharted seamounts by analysis of Seasat satellite altimetric data. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00268/37936/36017.pdf |
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