High-order accurate numerical models for magma migration beneath mid-ocean ridges: Geochemical consequences and geophysical implications

大洋中脊下岩浆迁移的高阶精确数值模型：地球化学后果和地球物理意义

• 批准号: 1156706
• 负责人: Yan Liang
• 金额: $ 40.95万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1156706&HistoricalAwards=false
• 关键词: order; accurate; numerical; models; magma

The generation of magmas in Earth's mantle and their segregation deep inside the Earth result in lavas that erupt from volcanoes on Earth's surface. How these processes take place and how they impart geochemical signatures in the resulting lavas is fundamental to our knowledge of how Earth behaves as a system. However, the processes that take place and complex interplay of geochemical and geophysicsl parameters that allow them to happen are presently inadequately understood. This research uses state-of-the-art numerical methods and computer algorithms and combines the expertise of both geosciences and applied mathematics to tackle the issues surrounding the physical and chemical proceses involved in partial melting of the mantle, melt migration, and melt-rock reaction in the generation of magma. From geochemical evidence gleaned from basaltic lavas erupted at mid-ocean ridge spreading centers, it is clear that the primary mechanism of melt transport requires the focusing of melt through channels in the mantle. However, the formation, distribution,and longieivy of these high-porosity channels is still a matter of speculation. To shed light on this problem, high order, adaptve, and parallel numerical models for simulating reactive magma migration in 2D and 3D settings directly relevant to melt migration below mid ocean ridges is being developed. The resulting simulation software will incorporate algorithms, approaches, and parameters that allow reactive dissolution of minerals, shear deformation, and decomperssional melting to be taken into account in models that calculate the distribution and segregation of melt. Additional considerations that link the geochemcial consequences and geophysical implications of melt migration will also be developed. The results will provide critical imput to general time-dependent melting models that allow geochemists to relate chemical heterogenaities observed in erupted basaltic lavas to their mantle sources. Broader impacts of the work include the funding of researchers at an institution in an EPSCoR state (Rhode island), building fundamental infrastructure for science via developing software that will be part of the Computational Infrastructure for Geodynamics software library which is publicly accessible, and training of undergraduates and graduate students in computational methods.

地幔中岩浆的产生和它们在地球深处的分离导致了地球表面火山喷发出的熔岩。这些过程是如何发生的，以及它们如何在产生的熔岩中传递地球化学特征，这是我们了解地球作为一个系统如何行为的基础。然而，所发生的过程以及使其发生的地球化学和地球物理学参数之间复杂的相互作用，目前还没有得到充分的了解。本研究采用最先进的数值方法和计算机算法，结合了地球科学和应用数学的专业知识，以解决涉及地幔部分熔融、熔体迁移和岩浆生成过程中熔融岩石反应的物理和化学过程。从洋中脊扩张中心喷发的玄武岩熔岩中收集到的地球化学证据表明，熔体运输的主要机制要求熔体通过地幔通道集中。然而，这些高孔隙度通道的形成、分布和寿命仍然是一个猜测问题。为了阐明这一问题，人们正在开发高阶、自适应、并行的数值模型，用于模拟与洋中脊以下熔融迁移直接相关的二维和三维活动岩浆迁移。由此产生的模拟软件将包含算法、方法和参数，这些算法、方法和参数允许在计算熔体分布和分离的模型中考虑矿物的活性溶解、剪切变形和分解熔融。还将进一步考虑将熔体迁移的地球化学后果和地球物理影响联系起来。这些结果将为一般的时间依赖熔融模型提供关键的输入，使地球化学家能够将在喷发的玄武岩熔岩中观察到的化学非均质性与其地幔来源联系起来。这项工作的广泛影响包括资助EPSCoR州（罗德岛州）的一个机构的研究人员，通过开发将成为地球动力学计算基础设施软件库的一部分的软件来建立科学的基础设施，该软件库是公开访问的，并培训本科生和研究生的计算方法。