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

地球动力学中尚未解决的主要问题之一是克拉通的稳定性和裂缝进入克拉通的物理条件。我们将测试的假设，岩浆过程在与羽流的克拉通的基础上，将导致熔体渗透前渗透到克拉通基地，释放挥发物在较浅的深度，削弱它，并最终协助不稳定和侵蚀的克拉通和岩石圈裂谷。东非裂谷系统与坦桑尼亚克拉通的相互作用被认为是这样一个过程的原型。我们将分两步建立物理模型。首先，在岩石圈软流层边界的熔体偏析，积累和渗透的动力学模型将开发调用弹粘塑性流变学的两相流和热量和熔体传输。将使用代码FDCON并进行相应修改。在构造应力场的存在下，并引入等效的各向异性渗透率分布，由此产生的预期熔体沟道的规模升级到堤坝传播将被用来开发参数化岩浆上升模型（PaMAM）。这个模型应该能够始终如一地模拟熔融提取熔融区和侵位的熔体在地幔岩石圈内较浅的深度。熔体侵位和冻结将包括在PaMAM模型中，以捕捉深度挥发物富集的影响。的PaMAM，然后将耦合到一个大规模的克拉通羽相互作用模型FDCON调查的物理参数，导致熔体渗透前和大规模削弱的地幔岩石圈，并集中向克拉通边缘的岩浆活动。将研究最终导致克拉通边缘或其内部断裂的条件。从坦桑尼亚克拉通的西部和东部边缘的观测限制将被用来验证新的克拉通不稳定和裂谷的方法。

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.