A Petrologic and Ion-Probe Study of Hornblende Gabbro Cumulates from Medicine Lake Volcano: An Evaluation of Competing Mechanisms of Calc-Alkaline Fractional...

分馏结晶是所有火成岩岩石学过程中最重要但了解最少的过程之一。理解分晶化如何运作的一个关键是通过研究在组成间隙形成事件中产生的岩浆堆积。这项研究将包括详细的结构（通用阶段）、地球化学、微探针，最重要的是，对梅迪辛湖沉积物的离子探针调查。结构研究将集中在矿物取向的优先程度上。地球化学研究将描述堆积物和伴生岩浆中主要元素和微量元素的变化。微探针和离子探针研究将确定单个堆积矿物的主要和微量元素分带样式，以及邻近堆积矿物之间的交感成分变化程度。总之，这些互补的证据线将用于评估梅迪辛湖的分离结晶的物理性质，并通过推断，在其他类似风格的钙碱性岩浆系统中。

Fractional crystallization is one of the most important yet most poorly understood of all igneous petrologic processes. One key to understanding how fractional crystallization operates is through the study of magmatic cumulates generated during a composition gap-forming event. This study will include detailed textural (Universal-Stage), geochemical, micro-probe and, most significantly, ion-probe investigations of the Medicine Lake cumulates. Textural studies will concentrate on the degree of preferred mineral orientation. Geochemical studies will characterize the major and trace element variability in both the cumulates and associated magmas. Micro-probe and ion-probe studies will determine major and trace element zonation styles in individual cumulate minerals, as well as the degree of sympathetic compositional variation among neighboring cumulate minerals. Altogether, these complimentary lines of evidence will be used to assess the physical nature of fractional crystallization at Medicine Lake and, by inference, in other calc-alkaline magmatic systems of similar style.