Spliting continental lithosphere during rifting in the South Atlantic with emphasis on the role of magmatism.

裂谷和裂解中最大的问题之一是，可用的力量可能不足以分割正常的大陆岩石圈(力悖论)。大多数今天的大陆边缘都与最初的裂谷期间大规模的火山喷发有关。上升的热浮地幔可以解释岩石圈在烟柱头部上方的受限区域的热减弱，但不能解释沿着裂谷轴线的裂谷和大陆分裂，裂谷轴线可能延伸到离烟柱数千公里的地方。这一建议遵循了工作假设，即除了地幔粘度的热降低外，还有两个进一步的过程在岩石圈分离中起着重要作用。(1)岩脉事件可能传播到大陆岩石圈，允许岩浆在比断层作用低得多的伸展应力下进行伸展；(2)裂谷尖端的应力集中可能允许裂谷的持续传播。我想研究是否需要大量与羽流有关的火成岩省份和相关的大型堤坝事件来解决力悖论，或者与裂谷尖端的被动上升流相关的应力集中和堤坝是否足够。南大西洋是这场争议的典型地区。在这里，我提出了一系列的2D和3D数值实验来研究这个问题。这些实验在边缘结构、下沉演化和岩浆历史方面的预测将与南大西洋的相同数据进行比较。反之亦然，南大西洋的情况将有助于建立这些实验。

One of the largest problems in rifting and breakup is that the available force might not be sufficient to part normal continental lithosphere (force paradox). Most present-day continental margins are associated with massive volcanic outflows during initial rifting. A rising plume of hot buoyant mantle would explain thermal weakening of the lithosphere in a confined area above the plume head but not rifting and continental breakup along a rift axis that might extend thousands of kilometers away from the plume. This proposal follows the working hypothesis that besides thermal reduction of mantle viscosity two further processes are important in parting the lithosphere. (1) Diking events might propagate into continental lithosphere allowing for magmatic accommodation of extension at much lower extensional stresses than faulting and (2) stress concentrations at the tip of a rift might allow for continuous propagation of the rift. I would like to study whether massive plume-related igneous provinces and associated huge diking events are required to solve the force paradox or if stress concentrations and diking associated with passive upwelling at a rift tip might suffice. The Southern Atlantic is a classic area for this controversy. Here, I propose a series of numerical 2D- and 3D-experiments to study this problem. Predictions of the experiments in terms of margin architecture, subsidence evolution and magmatic history will be compared with the same data from the South Atlantic. Vice versa, the situation in the South Atlantic will help to build the experiments.