The role of magmatic processes for Plume Craton Rift Interaction with application to the Tanzania craton and the East African Rift System: A physical approach

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One of the major unresolved questions in geodynamics is the stability of cratons and the physical conditions for rifts to penetrate into a craton. We will test the hypothesis that magmatic processes at the base of a craton associated with a plume will lead to a melt infiltration front penetrating into the craton base, release volatiles at shallower depth, weaken it and finally assist destabilization and erosion of the craton and rifting of the lithosphere. The interaction of the East African rift system with the Tanzania craton is regarded as a prototype of such a process. We will develop a physical model in two steps. First a dynamic model of melt segregation, accumulation and infiltration at the lithosphere asthenosphere boundary will be developed invoking elasto visco plastic rheology of two phase flow and heat and melt transport. The code FDCON will be used and modified accordingly. Upscaling of the resulting expected melt channeling to dyke propagation in the presence of a tectonic stress field and introduction of an equivalent anisotropic permeability distribution will be used to develop a parameterized magma ascent model (PaMAM). This model should be able to consistently model melt extraction from the melting zone and emplacement of melt at shallower depth within the mantle lithosphere. Melt emplacement and freezing will be included in the PaMAM model to capture the effect of volatile enrichment at depth. The PaMAM will then be coupled to a large scale craton plume interaction model with FDCON to investigate the physical parameters leading to a melt infiltration front and large scale weakening of the cratonic mantle lithosphere, and to focusing of magmatism towards the craton edges. Conditions leading eventually to rifting at the craton edge or its interior will be studied. Observational constraints from the Western and Eastern edge of the Tanzania craton will be used to validate the new craton destabilization and rifting approach.