Combining global and lithospheric-scale thermomechanical models of continental break-up in South Atlantic

在这个项目中，我们将使用岩石圈和全球尺度的热机械模型以及模拟模型来确定导致南非西缘解体和南大西洋形成的可能的驱动力和机械削弱因素。在全球数值模式(GFZ+慕尼黑)中，我们将研究冈瓦那周围俯冲带的可能作用以及全球地幔对流的影响，包括大羽流的到来在大陆岩石圈产生拉应力。然而，即使存在张应力，正常的大陆岩石圈也可能太强，无法被可用的板块构造力打破。因此，导致岩石圈减弱或应力集中或两者兼而有之的其他过程/因素必须参与解体，这些过程/因素仍然知之甚少。可能的候选者是：(1)地幔热柱的热和化学效应；(2)岩石圈下熔融和岩浆输送；(3)继承的岩石圈薄弱带；(4)应变减弱；(5)伸展裂谷尖端的应力集中；(6)伴随伸展的广泛的走滑变形。将使用岩石圈数值(GFZ)和模拟(VU阿姆斯特丹)3D建模技术来研究所有这些因素在破裂中的可能作用。最后，我们将结合岩石圈和全球范围的模型，并将使用来自其他样本项目的观测来验证模型情景。

In this project we will use thermomechanic models at both lithospheric and global scales as well as analog modeling to define possible driving forces and mechanical weakening factors that resulted in break-up at western margin of South Africa and formation of South Atlantics. In the global numerical models (GFZ+Munich) we will investigate possible role of subduction zones around Gondwana as well as effect of global mantle convection, including arrival of large plumes in generation of tensile stresses in the continental lithosphere. However, even if tensile stresses are there, the normal continental lithosphere is likely too strong to be broken by the available plate-tectonic forces. Therefore additional, still poorly understood, processes/factors leading either to the weakening of the lithosphere or to the stress concentration or to both, must be involved in the break-up. The possible candidates are: (i) thermal and chemical effect of mantle plume, (ii) sub-lithospheric melting and magma transport, (iii) inherited lithospheric weak zones, (iv) strain weakening, (v) stress concentration at the tip of propagating rift and (vi) extensive strike-slip deformation accompanied extension. The possible role of all those factors in break-up will be investigated using both lithospheric-scale numerical (GFZ) and analog (VU Amsterdam) 3D modeling techniques. Finally we will combine lithospheric and global scale models and will verify model scenarios using observations from other SAMPLE projects.