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力学模型以及模拟模型来定义可能的驱动力和机械弱化因素，这些因素导致了南非西部边缘的分裂和南大西洋的形成。在全球数值模型（GFZ+Munich）中，我们将研究冈瓦纳附近俯冲带的可能作用以及全球地幔对流的影响，包括在大陆岩石圈中产生拉应力的大羽流的到来。然而，即使存在拉伸应力，正常的大陆岩石圈也可能过于强大，无法被现有的板块构造力所破坏。因此，导致岩石圈减弱或应力集中或两者兼而有之的其他尚未得到充分了解的过程/因素必然涉及到这次破裂。可能的原因有：(1)地幔柱的热力和化学作用；(2)岩石圈下熔融和岩浆运移；(3)继承的岩石圈弱带；(4)应变减弱；(5)扩展裂谷尖端的应力集中；(6)广泛的走滑变形伴随伸展。所有这些因素在破裂中的可能作用将使用岩石圈尺度数值（GFZ）和模拟（VU Amsterdam） 3D建模技术进行研究。最后，我们将结合岩石圈和全球尺度模型，并将使用其他SAMPLE项目的观测结果验证模型情景。

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.