Quantitative Modeling of Infiltration in Layered Intrusions

9902183Boudreau 地球科学的一个主要研究领域是了解岩浆迁移的机制以及岩浆成分如何因这种迁移而变化。 重要的领域包括地幔熔体的地球化学以及了解这些熔体在迁移到地球表面时如何变化。此外，镁铁质层状侵入体中的渗透和反应已被认为是改变原生岩浆相的矿物学和组成的重要机制。在许多情况下，这些特征与铂族元素矿化有关；因此，这些问题也具有相当大的经济利益。 这项研究将液体-矿物平衡的定量模型与一维输运方程相结合，开发一个用于模拟岩浆反应-输运现象的程序。该程序预计将成为广泛火成岩研究的有用工具。 该程序足够通用，因此用户可以指定一系列起始成分（包括不均匀的主岩成分）。 例如，该程序将允许计算硅酸盐液体渗透穿过多孔固体基质时的反应和色谱前沿。除了理论建模之外，我们还计划对南非布什维尔德综合体的结构、化学和矿物学特征进行并行实地研究。这些实地研究将有助于约束和比较数值模型的结果。

9902183BoudreauA major field of inquiry in the earth sciences is the understanding of mechanisms of magma migration and how magma compositions can change as a result of this migration. Areas where this is of importance include the geochemistry of mantle melts and the understanding of how these melts change as they migrate to the surface of the earth. In addition, infiltration and reaction in mafic layered intrusions has been recognized as an important mechanism in changing both the mineralogy and composition of primary magmatic phases. In a number of cases, these features are associate with platinum-group element mineralization; hence, there is considerable economic interest in these problems as well. This study will combine a quantitative model for liquid-mineral equilibria with one-dimensional transport equations to develop a program for modeling magmatic reaction-transport phenomenon. The program is expected to be a useful tool to a broad range of igneous studies. This program will be general enough so users can specify a range of starting compositions (including inhomogeneous host rock compositions). For example, the program will allow calculation of reaction and chromatographic fronts as silicate liquid percolates through a porous solid matrix. In addition to the theoretical modeling, we plan parallel field studies of textural, chemical and mineralogical features of the Bushveld complex, South Africa. These field studies will help to constrain and compare results of the numerical models.