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.

地幔中岩浆的产生及其在地球深处的分离导致了地球表面火山喷发的熔岩。 这些过程如何发生以及它们如何在产生的熔岩中传递地球化学特征是我们了解地球作为一个系统如何运行的基础。 然而，目前人们对所发生的过程以及使这些过程发生的地球化学和地球物理参数之间复杂的相互作用还没有充分了解。这项研究采用最先进的数值方法和计算机算法，结合地球科学和应用数学的专业知识，解决岩浆生成过程中地幔部分熔融、熔体迁移和熔岩反应所涉及的物理和化学过程的问题。从大洋中脊扩张中心喷发的玄武岩熔岩收集的地球化学证据来看，很明显，熔体输送的主要机制需要熔体通过地幔通道聚焦。然而，这些高孔隙率通道的形成、分布和寿命仍然是一个猜测。为了阐明这个问题，正在开发高阶、自适应和并行数值模型，用于模拟与大洋中脊以下熔体迁移直接相关的 2D 和 3D 设置中的反应岩浆迁移。由此产生的模拟软件将包含算法、方法和参数，允许在计算熔体分布和偏析的模型中考虑矿物的反应溶解、剪切变形和解压缩熔融。 还将制定将熔体迁移的地球化学后果和地球物理影响联系起来的其他考虑因素。 这些结果将为一般的随时间变化的熔融模型提供关键信息，使地球化学家能够将喷发的玄武岩熔岩中观察到的化学异质性与其地幔来源联系起来。 这项工作的更广泛影响包括为 EPSCoR 州（罗德岛州）的一个机构的研究人员提供资助，通过开发软件来建设科学基础设施，该软件将成为可公开访问的地球动力学计算基础设施软件库的一部分，以及对本科生和研究生进行计算方法方面的培训。