Modeling Mantle Circulation, Temperatures and Melting Processes Beneath Back-Arc Spreading Centers

摘要（Kincaid - 0453656）地球内部是一个对流引擎，它产生了我们的大陆、海洋和大气，并随着时间的推移继续重塑它们。 板块分离的扩张脊和板块会聚的俯冲带是地球内部与海洋和大气之间进行能量和化学交换的主要场所。 俯冲带尤其重要，因为它们位于大陆边缘附近，那里居住着大量且不断增长的地球人口。 俯冲带也产生了有记录的历史上所有的大地震，沿着各种俯冲引起的危险，包括熔岩流;火山碎屑流;和毁灭性的海啸。 这项研究测试的假设，即存在一个扩张中心以上俯冲板块显着修改系统的地幔流（和应力场），温度，熔体和新地壳的生产。 二维（2-D）的数值模型和一种新的装置，用于三维（3-D）的实验室模拟模型的俯冲弧后扩张。 结果将表征地幔环流模式，地幔温度，以及在这些复杂的系统内产生和提取的熔体的类型和体积的变化之间的关系。 将生成数值模型，以显示在全球弧系统中观察到的不同俯冲参数如何影响地幔过程和二维意义上的地壳生长。 这些结果将用于计算熔融离开地幔的特征，并通过与现有的化学数据进行比较，将重点放在实际系统可能出现的情况上。 实验室模型，开发与以前的NSF资金，规模以及地幔，将被用来表征的三维空间和时间模式的地幔流，应力，温度和熔体生产在复杂的地区，俯冲和板块扩张过程相互作用。 实验室模型的三维方面允许与现有数据集进行有效的比较，超越了二维计算机模型的可能性。 更广泛的影响

ABSTRACT (Kincaid - 0453656) The Earth's interior represents a convective engine that generated our continents, oceans and atmosphere and continues to reshape them over time. Spreading ridges, where plates move apart, and subduction zones where plates converge, represent the dominant sites for energy and chemical exchange between Earth's interior and our oceans and atmosphere. Subduction zones, in particular, are important because they occur near continental margins where a large and growing percentage of Earth's population resides. Subduction zones have also produced all of the great earthquakes in recorded history, along with a variety of subduction-induced hazards including lava flows; pyroclastic flows; and devastating tsunamis. This research tests the hypothesis that the presence of a spreading center above a subducting plate dramatically modifies the system in terms of mantle flow (and stress fields), temperatures, and the production of melt and new crust. Two-dimensional (2-D) numerical models and a novel apparatus for three-dimensional (3-D) laboratory analog models of subduction with back-arc spreading are used. Results will characterize relationships between mantle circulation patterns, mantle temperatures, and variability in the types and volumes of melt that are produced and extracted from within these complex systems. Numerical models will be generated to show how different subduction parameters observed in the global arc system influence mantle processes and crustal growth in a 2-D sense. These results will be used to calculate the characteristics of melt leaving the mantle and, through comparisons with available chemical data, will allow focus to be brought on scenarios that are possible for the actual system. Laboratory models, developed with prior NSF funding that scale well to the mantle, will be used to characterize the 3-D spatial and temporal patterns in mantle flow, stress, temperature, and melt production in complex regions where subduction and plate spreading processes interact. The 3-D aspects of the laboratory models allow for effective comparisons with existing data sets, going beyond what is possible with 2-D computer models. Broader Impacts