A Study of Trapped Liquid Variations and Coupled Chemical Trends in the Keweenawan Beaver Bay Gabbro Complex, Minnesota

这项建议是发展技术， 堆积物来自海狸岩石中的堆积物成分 海湾辉长岩复杂，明尼苏达州，使用背散射扫描电镜成像， Normanski干涉对比显微镜和电子显微镜 探头导线 从这项研究中， 丰度（即，原始孔隙度）将通过 所有累积成分的总和，以类似的方式 砂岩中原始孔隙度的估计。 主量元素、稀土元素及其它微量元素的研究 整个岩石和矿物分离物的变化也是 为了研究整个岩石之间的关系， 化学成分、丰度和组成 累积相位 我们也希望了解 在捕获的液体量的变化和 液体的组成，并测试是否假设 涉及杜卢斯中成分均匀的捕获液体 Beaver Bay辉长岩。 体积相对较小，曝光度极佳， 地层层序和极端铁富集差异， 海狸湾辉长岩的走向使其非常适合于 这里提出的研究。 从这项研究中获得的数据 也会导致母岩浆的特征 组合物，其中结晶顺序的描述 岩石，以及对强铁形成过程的理解， 络合物中有富集结晶趋势。

This proposal is to develop techniques for distinguishing cumulate from intercumulate components in rocks from the Beaver Bay gabbro complex, Minnesota, using backscatter SEM imaging, Normanski interference-contrast microscopy, and electron micro- probe traverse. From this study the trapped intercumulus liquid abundance (i.e., original porosity) will be estimated through summation of all intercumulate components, in a manner analogous to original porosity estimates in sandstones. A major study of major element, REE, and other trace element variations in whole-rocks and in mineral separates is also proposed in order to examine the relationships between whole-rock chemical composition and abundance and composition of the cumulate phases. We also wish to understand the relationship between the variation in the amount of trapped liquid and the composition of the liquid, and to test whether the hypothesis involving a compositionally uniform trapped liquid in the Duluth complex applies to Beaver Bay gabbro. The relatively small size, excellent exposure, complete stratigraphic sequence, and extreme iron-enrichment differentia- tion trend of the Beaver Bay gabbro make it well suited for the kind of study proposed here. The data obtained from this study will also lead to the characterization of the parent magma composition(s), a description of the crystallization sequences in the rocks, and an understanding of the processes to strong iron- enrichment crystallization trends in the complex.