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Geodynamics since the Jurassic and mantle convection.

Abstract : The dynamics of mantle convection and its relation to plate motion and plate boundary deformation has been so far mostly studied through numerical modeling but as the rheology of the mantle is not precisely known, testing the models is difficult. If one could relate deep convection with the geological evolution recorded through time, one may have access to time constants of convection cycles, slab penetration and slab detachment, tearing. We look for such possible connexions in the tectonic history of the Tethys Ocean. The tectonic history of the Neo- Tethys ocean and of the mountain belts formed during its progressive closure are characterized by (1) the fragmentation of southern continental masses and fast northward drift of smaller continents that end up subducting and colliding with the southern margin of the northern continents, (2) one major compressional event in the Late Cretaceous leading to generalized obduction on the northern margins of Africa and Apulia contemporaneous with generalized compression in the northern part of Africa and part of Eurasia and (3) opening and closure of backarc basins formed within the southern margin of Eurasia, especially in the Mediterranean region. Based on reconstructions and a synthesis of various indicators of mantle convection, such as plate velocities, oceanic lithosphere production or super plumes activity, we discuss a model describing the relations between lithospheric-scale geodynamics in the Tethys region and mantle convection cycles, slab penetration and detachments. We propose that the fragmentation of Africa (Apulia, Arabia) resulted from the drag of the underlying mantle flowing northward and that the Late Cretaceous compressional event and large-scale obduction resulted from the penetration of the Tethyan slab in the lower mantle. The noncoaxial component induced by basal drag induced the underthrusting of the old and cold continental mantle below the younger oceanic mantle, leading to obduction.
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Submitted on : Monday, March 21, 2016 - 2:08:26 PM
Last modification on : Wednesday, September 23, 2020 - 4:37:58 AM


  • HAL Id : insu-01291374, version 1


Laurent Jolivet, Claudio Faccenna, Philippe Agard, Dominique Frizon de Lamotte, Armel Menant, et al.. Geodynamics since the Jurassic and mantle convection.. 24ème Réunion des Sciences de la Terre, RST, Oct 2014, Pau, France. ⟨insu-01291374⟩