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Titolo:
Stagnant slabs in the upper and lower mantle transition region
Autore:
Fukao, Y; Widiyantoro, S; Obayashi, M;
Indirizzi:
Univ Tokyo, Earthquake Res Inst, Tokyo 113, Japan Univ Tokyo Tokyo Japan113 Tokyo, Earthquake Res Inst, Tokyo 113, Japan Inst Technol, Dept Geophys & Meteorol, Bandung, Indonesia Inst Technol Bandung Indonesia t Geophys & Meteorol, Bandung, Indonesia Meteorol Res Inst, Seismol & Volcanol Res Dept, Tsukuba, Ibaraki 305, Japan Meteorol Res Inst Tsukuba Ibaraki Japan 305 , Tsukuba, Ibaraki 305, Japan
Titolo Testata:
REVIEWS OF GEOPHYSICS
fascicolo: 3, volume: 39, anno: 2001,
pagine: 291 - 323
SICI:
8755-1209(200108)39:3<291:SSITUA>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH-VELOCITY ANOMALIES; ENDOTHERMIC PHASE-TRANSITION; TRAVEL-TIME TOMOGRAPHY; 660 KM DISCONTINUITY; EARTHS MANTLE; SUBDUCTION ZONE; SEISMIC DISCONTINUITY; NORTHWEST PACIFIC; HIGH-RESOLUTION; PLATE MOTION;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
156
Recensione:
Indirizzi per estratti:
Indirizzo: Fukao, Y Univ Tokyo, Earthquake Res Inst, 7-3-1 Hongo, Tokyo 113, Japan Univ Tokyo 7-3-1 Hongo Tokyo Japan 113 1 Hongo, Tokyo 113, Japan
Citazione:
Y. Fukao et al., "Stagnant slabs in the upper and lower mantle transition region", REV GEOPHYS, 39(3), 2001, pp. 291-323

Abstract

We made a region-by-region examination of subducted slab images along the circum-Pacific for some of the recent global mantle tomographic models, specifically for two high-resolution P velocity models and two long-wavelengthS velocity models. We extracted the slab images that are most consistent among different models. We found that subducted slabs tend to be subhorizontally deflected or flattened in the upper and lower mantle transition region, the depth range of which corresponds roughly to the Bullen transition region (400-1000 km). The deflected or flattened slabs reside at different depths, either above or across the 660-km discontinuity as in Chile Andes, Aleutian, Southern Kurile, Japan, and Izu-Bonin; slightly below the discontinuity as in Northern Kurile, Mariana, and Philippine; or well below it as in Peru Andes, Java, and Tonga-Kermadec. There is little indication for most of these slabs to continue "directly" to greater depths well beyond the transition region. Mantle downflow associated with present slab subduction appears to be blocked strongly to turn into predominantly horizontal flow in the transition region. Recent global tomographic models show also a group of lithospheric slabs deeply sinking through the lower mantle, typically the presumed Farallon slab beneath North and Central America and the presumed Indian (Tethys) slab beneath Himalaya and the Bay of Bengal. These remnant slabs are not connected to the surface plates or to the presently subducting slabs and appear to sink independently from the latter. The presence of these deeply sinking slabs implies that the pre-Eocene subduction occurred in much the same way as in the present day to accumulate slab bodies in the transition region and that the consequent unstable downflow occurred extensively through the transition region in the Eocene epoch to detach many of thesurface plates from the subducted slabs at depths and hence to cause the reorganization of global plate motion.

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Documento generato il 19/01/20 alle ore 09:22:53