Lithospheric Controls on Flood Basalt Volcanism

大陆洪水玄武岩省是神秘的，因为它们在地质记录中不常见，它们的规模惊人（至少105公里立方的熔岩），它们的形成速度（西伯利亚和其他几个地区在大约100万年内完成），它们的明显或可能的年龄与其他陆地灾难一致，包括灭绝，陨石撞击和海平面变化。西伯利亚洪水玄武岩省是最大的玄武岩省之一，与地球历史上最大的二叠纪大灭绝时间密切吻合。因此，了解触发和创造大陆洪水玄武岩的过程不仅与地质学和地球物理学有关，而且可能与地球上的生命循环以及全球化学系统的相互作用有关。洪水玄武岩是连接地球进化和地球上生命进化的纽带。这项工作的目的是帮助区分洪水玄武岩形成的相互竞争的理论，更具体地说，是为了更好地理解岩石圈在触发和喷发中的作用。该项目将实验岩石学和数值模拟相结合。这项工作将由私家侦探完成，并将构成至少一名布朗大学本科生的本科论文。这项工作将由两部分组成：1。西伯利亚高氧化镁岩浆的高压温度实验及其形成压力和温度评价和2。数值模拟研究岩石圈沉降作为岩浆焦点和触发因素的作用，研究克拉通边缘岩石圈地形及其对地幔柱上升的影响。本项目将是我国首批对原始洪泛玄武岩组成进行实验研究的项目之一。实验研究的结果有可能区分需要非常深的热熔融的熔岩模型和在较低温度下熔融的其他地幔岩性模型。这些结果可能会显著改变洪水玄武岩形成的模型。

EAR-0309057Elkins-TantonContinental flood basalt provinces are enigmatic due to their infrequency in the geologic record, their remarkable size (at least 105 km3 of lava), their speed of formation (the Siberian and several others were complete in about a million years) and their apparent or possible age coincidences with other terrestrial catastrophes, including extinctions, meteorite impacts, and sea level changes. The Siberian flood basalt province, one of the largest, is also closely coincident in time with the Permian extinction, the largest in Earth history. Understanding the processes that trigger and create continental flood basalts therefore has relevance not only to geology and geophysics, but possibly to cycles of life on earth and certainly to interactions of global chemical systems. Flood basalts are a link between the evolution of the Earth and evolution of life on Earth.The work is designed to help differentiate among competing theories for the formation of flood basalts, and, more specifically, to create better understanding of the role of lithosphere in triggering and eruption. The project bridges the fields of experimental petrology and numerical modeling. The work will be carried out by the P.I. and will also constitute the undergraduate thesis of at least one Brown University undergraduate. The work will consist of two parts: 1. High-pressure and temperature experiments on high-MgO magmas from Siberia to assess their pressure and temperature of formation; and 2. Numerical modeling to study the role of lithospheric foundering as a magmatic focus and trigger, and to study lithospheric topography at the edge of cratons and how it affects plume ascent.This project will be one of the first experimental studies on primitive flood basalt compositions. The results of the experimental study have the potential to differentiate between models for lavas requiring very deep, hot melting, and models suggesting alternative mantle lithologies melting at lower temperatures. These results may significantly alter models for flood basalt formation.