MELTING, MELT MIGRATION, AND VOLCANISM AT CONVERGENT PLATE BOUNDARIES

汇聚板块边界处的熔融、熔融迁移和火山作用

• 批准号: 0728028
• 负责人: E M Parmentier
• 金额: $ 30.09万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0728028&HistoricalAwards=false
• 关键词: MELTING; MELT; MIGRATION; VOLCANISM; CONVERGENT

Intellectual Merit: The production of melt (magma) in the Earth's upper mantle at convergent plate boundaries is believed to arise from one or both of two processes: flux melting, as the water released by dehydration of the down-going plate rises into the hot center of the mantle wedge; and decompression melting of the hot mantle as it rises into the wedge. The project aims to study the relative contributions of these two melt-generation processes, since they are believed to govern a number of critically-important geological conditions. A numerical model will be developed that incorporates the physics of melt migration, and this will be used to predict the varying geology at convergent margins. It is hypothesized that the spatial variation in geochemical composition within volcanic systems at convergent margins may be attributable to the variable mixing of magmas originating from both flux and adiabatic decompression melt processes. This hypothesis will be tested by examining observed convergent margin volcanism and comparing the range of chemical compositions, and their geographic distribution, to 2D and 3D numerical model outputs determined by the variable contribution of flux and decompression melts. The mechanisms by which channeling of ponded magma within the decompaction boundary layer may be localized to form distinct volcanic centers will be investigated. Why are volcanoes spaced apart as they are? What governs the separation between distinct volcanic centers? Might this process be explained by studies of fingering instabilities? Fingering instabilities within the decompaction channel if disparate melts are mixed will be explored using analytical and numerical models. Alternatively, the buoyant percolation of smaller bodies of melt due to localized wet melting within an otherwise diapiric upwelling setting will be investigated by considering the impact of slab dehydration on an olivine-pyroxene mantle and dissolution melt instabilities.Broader Impacts: The project includes research and training experiences for undergraduate and graduate students, with graduate student teaching opportunities via the Sheridan Center for Teaching and Learning at Brown, and research activities for upper division undergraduates. The graduate and undergraduate students involved in the project will participate in 4th grade outreach activities in local schools. Wider scientific impacts include synergies with numerous seismic and theoretical studies at a variety of convergent margins, and the development of numerical modeling codes that will build the research infrastructure for computational geodynamics. The methods developed will also have a bearing on studies of porous flow in viscous compacting solids in a variety of fields, potentially including petroleum recovery and exploration.

智力优点：据信，在收敛板边界的地球上地幔中的熔体（岩浆）的产生是由两个过程中的一个或两个过程中产生的：通量熔化，因为下降板的脱水释放到了向下板的水释放到地幔楔的热中心；当热地幔升入楔子时，减压融化。该项目旨在研究这两个熔融生成过程的相对贡献，因为它们被认为控制着许多至关重要的地质条件。将开发一个结合熔体迁移物理学的数值模型，这将用于预测收敛边缘的不同地质。假设在收敛边缘处火山系统内的地球化学组成的空间变化可能归因于岩浆的可变混合，这些岩浆源自磁通量和绝热减压融化过程。该假设将通过检查观察到的收敛边缘火山趋势，并将化学成分及其地理分布的范围与2D和3D数值模型输出进行比较。可以将分解边界层中岩浆通道通道的机制进行定位，以形成不同的火山中心。为什么火山会像以前那样隔开？是什么控制着不同火山中心之间的分离？这个过程是否可以通过指法不稳定性来解释？如果混合不同的融化，则使用分析和数值模型探索分解通道内的指法不稳定性。另外，将通过考虑将板脱水对橄榄石脱水对橄榄石脱水的影响来调查较小的熔体熔体熔体熔体的浮雕，并将调查，以研究和培训的培训，包括研究和培训的培训，并包括研究生的培训和研究生的培训。上层本科生的研究活动。参与该项目的研究生和本科生将参加当地学校的四年级外展活动。更广泛的科学影响包括各种收敛缘具有大量地震和理论研究的协同作用，以及将开发数值建模代码，这些代码将建立计算地球动力学的研究基础设施。开发的方法还将与多孔压实固体中多孔流动的研究有关，可能包括石油恢复和勘探。