Developing Models of Melt Transfer in Migmatites - A Pilot Study

开发混合岩熔体转移模型 - 一项试点研究

• 批准号: 9814259
• 负责人: Michael Brown
• 金额: $ 5.76万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-01 至 2000-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814259&HistoricalAwards=false
• 关键词: Developing; Models; Melt; Transfer; Migmatites

9814259BrownThe primary goal of the proposed work is to identify the scale or scales of the processes that control melt transfer in migmatitic rocks. This information will allow the production of realistic models of transport properties of migmatites with respect to melt, which will serve to perfect integrated numerical models of melt segregation and migration within, through, and out of migmatitic rocks. Specific steps will include: 1) the characterization, using high-resolution X-ray computed tomography, of the 3-D distribution of leucosome in a migmatite (as a proxy for mesoscopic melt advection network) from the Onawa contact metamorphic aureole; 2) the derivation of mesoscopic permeability estimates from deterministic models of flow through the network defined in 1; 3) the characterization of inter-leucosome compositional gradients (i.e., in mesosome) within that migmatite, using the electron microprobe analyzer and image analysis techniques; 4) the derivation of bulk diffusivities associated with these gradients by applying appropriate analytical solutions to the diffusion equation, as well as error minimization methods; 5) comparison of the resulting rates of inter-leucosome material transport with rates of melt advection in the leucosome network, in order to identify the scale or scales of the processes that control the overall movement of melt through these rocks; and 6) assessment of different types of spatial distribution models for transport properties of migmatites, in light of these results. Developing models of melt transfer in migmatites is a necessary step in understanding crustal-scale melt transport because any geometric model of focussed granite ascent requires extensive migration of material through the source region.

9814259 Brownard提出的工作的主要目标是确定控制混合岩中熔体转移的过程的规模。这些信息将允许生产的混合岩相对于熔体，这将有助于完善综合的熔体隔离和迁移内，通过和混合岩的数值模型的运输性能。具体步骤将包括：1）使用高分辨率X射线计算机断层摄影术，表征来自Onawa接触变质晕的混合岩中的白色体的3-D分布（作为介观熔体平流网络的代理）; 2）从通过1中定义的网络的流动的确定性模型导出介观渗透率估计; 3）白色体间成分梯度的表征（即，4）通过对扩散方程应用适当解析解以及误差最小化方法，推导出与这些梯度相关的体扩散系数; 5）比较白细胞体间物质输送的速率与白细胞体网络中融化平流的速率，以确定控制熔体通过这些岩石的整体运动的过程的规模或规模;和6）根据这些结果，评估混合岩输运性质的不同类型的空间分布模型。在混合岩熔体传输模型的发展是一个必要的步骤，了解地壳规模的熔体输送，因为任何几何模型的集中花岗岩上升需要广泛的迁移材料通过源区。