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Titolo:
Lithospheric structure of a nascent spreading ridge inferred from gravity data: The western Gulf of Aden
Autore:
Hebert, H; Deplus, C; Huchon, P; Khanbari, K; Audin, L;
Indirizzi:
Inst Phys Globe, CNRS, UMR 7577, Lab Gravimetrie & Geodynam, F-75252 Paris05, France Inst Phys Globe Paris France 05 trie & Geodynam, F-75252 Paris05, France Ecole Normale Super, Geol Lab, F-75231 Paris, France Ecole Normale Super Paris France F-75231 Geol Lab, F-75231 Paris, France Inst Phys Globe, CNRS, Lab Tecton & Mecan Lithosphere, UMR 7578, F-75252 Paris 05, France Inst Phys Globe Paris France 05 here, UMR 7578, F-75252 Paris 05, France
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B11, volume: 106, anno: 2001,
pagine: 26345 - 26363
SICI:
0148-0227(20011110)106:B11<26345:LSOANS>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
MID-ATLANTIC RIDGE; SOMALIA PLATE BOUNDARY; RED-SEA; CONTINENTAL-MARGIN; CRUSTAL THICKNESS; AFAR DEPRESSION; REYKJANES RIDGE; BLOCK ROTATION; SOUTHERN AFAR; RIFT SYSTEM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
61
Recensione:
Indirizzi per estratti:
Indirizzo: Hebert, H Inst Phys Globe, CNRS, UMR 7577, Lab Gravimetrie & Geodynam, 4 Pl Jussieu,F-75252 Paris 05, France Inst Phys Globe 4 Pl Jussieu Paris France 05 2 Paris 05, France
Citazione:
H. Hebert et al., "Lithospheric structure of a nascent spreading ridge inferred from gravity data: The western Gulf of Aden", J GEO R-SOL, 106(B11), 2001, pp. 26345-26363

Abstract

The Aden spreading ridge (Somalia/Arabia plate boundary) does not connect directly to the Red Sea spreading ridge. It propagates toward the East African Rift through the Afar depression, where the presence of a hot spot has been postulated from seismological and geochemical evidence. The spreading direction (N37 degreesE) is highly oblique to the overall trend (N90 degreesE) of the ridge. We present and interpret new geophysical data gathered during the Tadjouraden cruise (RN L'Atalante, 1995) in the Gulf of Aden west of 46 degreesE. These data allow us to study the propagation of the ridge toward the Afar and to discuss the processes of the seafloor spreading initiation. We determine the lithospheric structure of the ridge using gravity data gathered during the cruise with the constraint of available refraction data. A striking Bouguer anomaly gradient together with the identification of magnetic anomalies defines the geographical extent of oceanic crust. Theinversion of the Bouguer anomaly is performed in terms of variations of crustal thickness only and then discussed with respect to the expected thermal structure of the mantle lithosphere, which should depend not only on the seafloor spreading but also on the hot spot beneath East Africa. Our results allow us to define three distinct lithospheric domains in the western Gulf of Aden. East of 44 degrees 45'E the lithosphere displays an oceanic character (thermal subsidence recorded for the last 10 Ma and constant crustal thickness). Between 43 degrees 30'E and 44 degrees 10'E the lithosphere is of continental type but locally thinned beneath the axial valley. The central domain defined between 44 degrees 10'E and 44 degrees 45'E is characterized by a transitional lithosphere which can be seen as a stretched continental crust where thick blocks are mixed with thinned crust; it displays en echelon basins that are better interpreted as extension cells rather than accretion cells.

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Documento generato il 18/01/20 alle ore 21:39:09