Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.21/3593
Título: Convective patterns under the Indo-Atlantic << box >>
Autor: Davaille, A.
Stutzmann, E.
Silveira, G.
Besse, J.
Courtillot, V
Palavras-chave: Convection
Mantle plumes
Hotspots
Traps
Tomography
Core-Mantle Boundary
2-Layer Thermal-Miscible Viscous Fluids
Plate Driving Forces
True Polar Wander
Flood Basalts
Deep Mantle
African Superswell
Dynamic Topography
Seismic Tomography
Data: 15-Nov-2005
Editora: Elsevier Science BV
Citação: DAVAILLE, A.; STUTZMANN, E.; SILVEIRA, G.; BESSE, J.; COURTILLOT, V. - Convective patterns under the Indo-Atlantic << box >>. Earth and Planetary Science Letters. ISSN 0012-821X. Vol. 239, nr. 3-4 (2005), p. 233-252.
Resumo: Using fluid mechanics, we reinterpret the mantle images obtained from global and regional tomography together with geochemical, geological and paleomagnetic observations, and attempt to unravel the pattern of convection in the Indo-Atlantic "box" and its temporal evolution over the last 260 Myr. The << box >> presently contains a) a broad slow seismic anomaly at the CMB which has a shape similar to Pangea 250 Myr ago, and which divides into several branches higher in the lower mantle, b) a "superswell, centered on the western edge of South Africa, c) at least 6 "primary hotspots" with long tracks related to traps, and d) numerous smaller hotspots. In the last 260 Myr, this mantle box has undergone 10 trap events, 7 of them related to continental breakup. Several of these past events are spatially correlated with present-day seismic anomalies and/or upwellings. Laboratory experiments show that superswells, long-lived hotspot tracks and traps may represent three evolutionary stages of the same phenomenon, i.e. episodic destabilization of a hot, chemically heterogeneous thermal boundary layer, close to the bottom of the mantle. When scaled to the Earth's mantle, its recurrence time is on the order of 100-200 Myr. At any given time, the Indo-Atlantic box should contain 3 to 9 of these instabilities at different stages of their development, in agreement with observations. The return flow of the downwelling slabs, although confined to two main << boxes >> (Indo-Atlantic and Pacific) by subduction zone geometry, may therefore not be passive, but rather take the form of active thermochemical instabilities. (c) 2005 Elsevier B.V. All rights reserved.
Peer review: yes
URI: http://hdl.handle.net/10400.21/3593
ISSN: 0012-821X
Versão do Editor: http://www.sciencedirect.com/science/article/pii/S0012821X05005200
Aparece nas colecções:ISEL - Física - Artigos

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