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

南大西洋裂谷期间大陆岩石圈的分裂，强调岩浆作用的作用。

• 批准号: 79624106
• 负责人: Professor Dr. Thorsten Nagel
• 金额: --
• 依托单位: Lamont-Doherty Earth Observatory
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/79624106?language=en
• 关键词: Spliting; continental; lithosphere; during; rifting

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.

裂陷和解体的最大问题之一是可用的力可能不足以分开正常的大陆岩石圈（力悖论）。大多数现今的大陆边缘都与初始裂陷过程中的大量火山外流有关。上升的热浮力地幔柱可以解释在地幔柱头部上方的一个封闭区域内岩石圈的热弱化，但不能解释沿着沿着可能延伸到数千公里以外的裂谷轴的裂谷和大陆分裂。这一建议遵循的工作假设，除了地幔粘度的热还原两个进一步的过程是重要的岩石圈分离。(1)脉冲活动可能传播到大陆岩石圈，允许岩浆在比断层低得多的伸展应力下容纳伸展;（2）裂谷尖端的应力集中可能允许裂谷的持续扩展。我想研究是否需要大规模的羽状相关的火成岩省和相关的巨大的堤防事件，以解决力的悖论，或者如果应力集中和堤防与被动上涌在裂谷尖端可能就足够了。南大西洋是这场争论的典型地区。在这里，我提出了一系列的数值2D和3D实验来研究这个问题。预测的实验方面的边缘架构，沉降演化和岩浆史将与来自南大西洋的相同数据进行比较。反之亦然，南大西洋的局势将有助于建立实验。