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Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2013

Buoyancy and localizing properties of continental mantle lithosphere: Insights from thermomechanical models of the eastern Gulf of Aden

Résumé

Physical properties of the mantle lithosphere have a strong influence on the rifting processes and rifted structures. In particular, in context of rifting, two of these properties have been overlooked: (1) Mohr-Coulomb plasticity (localizing pressure-dependent) may not be valid at mantle depths as opposed to non-localizing pressure-independent plasticity (hereafter, perfect plasticity), and (2) lithosphere buoyancy can vary, depending on the petrological composition of the mantle. Focussing on the Arabian plate, we show that the lithosphere may be negatively buoyant. We use thermomechanical modeling to investigate the importance of mantle rheology and composition on the formation of a passive margin, ocean-continent transition (OCT) and oceanic basin. We compare the results of this parametric study to observations in the eastern Gulf of Aden (heat-flow, refraction seismics and topography) and show that (1) mantle lithosphere rheology controls the margin geometry and timing of the rifting; (2) lithosphere buoyancy has a large impact on the seafloor depth and the timing of partial melting; and (3) a perfectly plastic mantle lithosphere 20 kg m−3 denser than the asthenosphere best fits with observed elevation in the Gulf of Aden. Finally, thermomechanical models suggest that partial melting can occur in the mantle during the Arabian crustal break-up. We postulate that the produced melt could then infiltrate through the remnant continental mantle lithosphere, reach the sur- face and generate oceanic crust. This is in agreement with the observed narrow OCT composed of exhumed continental mantle intruded by volcanic rocks in the eastern Gulf of Aden.
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Dates et versions

hal-00826216 , version 1 (27-05-2013)

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Louise Watremez, Evgenii E.B. Burov, Elia d'Acremont, Sylvie Leroy, Benjamin Huet, et al.. Buoyancy and localizing properties of continental mantle lithosphere: Insights from thermomechanical models of the eastern Gulf of Aden. Geochemistry, Geophysics, Geosystems, 2013, 14 (8), pp.2800-2817. ⟨10.1002/ggge.20179⟩. ⟨hal-00826216⟩
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