U.S.-Costa Rica Dissertation Enhancement: The Origin of Silicic Magmas in an Island Arc; A Study of the Valle Central Chemical Zoned Ash-Flow

在密歇根州立大学Thomas Vogel博士的指导下，Rachel Hannah女士将获得这项美洲项目的论文加强资助，以研究硅岩浆的起源，这是一个在没有大陆地壳的岛弧上不寻常的现象。该研究将与哥斯达黎加大学地质学院的Guillermo Alvarado博士合作进行。为了确定哥斯达黎加高硅质岩浆的起源这一长期目标，研究人员将对中部火山山脉的高度分带火山灰流沉积物进行具体、详细的研究，并与哥斯达黎加西北部瓜纳卡斯特火山山脉的体积火山灰流层进行初步比较。她将研究谷地中心火山灰流层的化学变化，将化学地层学和物理地层学结合成一个模型进行就位并解释结果。获得的数据将有助于更好地了解大陆地壳的起源和演化，并可能解决为什么在某些岛弧系统中产生了硅质岩浆而在其他岛弧系统中没有产生的基本问题。哥斯达黎加大学（UCR）和密歇根州立大学（MSU）在研究能力上互补。CRU可以提供有价值的当地地质知识和对该地区物理火山学的了解，密歇根州立大学的研究人员带来了化学岩石学方面的专业知识和深入地球化学研究所需的分析设备。＊＊＊

9819236VogelThis Americas Program award will fund a dissertation enhancement grant for Ms. Rachel Hannah, under the supervision of Dr. Thomas Vogel, Michigan State University, for a study of the origin of silicic magmas, an unusual occurrence in an island arc where there is no continental crust. The research will be conducted in collaboration with Dr. Guillermo Alvarado, School of Geology, University of Costa Rica. With the long-range goal of determining the origin of the high-silica-magmas that occur in Costa Rica, the researcher will conduct a specific, detailed study of the highly zoned ash-flow deposits of the Central volcanic range and a preliminary comparison with the volume ash-flow sheets in the Guanacaste volcanic range in northwestern Costa Rica. She will work on the chemical variation of the Valle Central ash-flow sheet, combining the chemical stratigraphy and the physical stratigraphy into one model for emplacement and interpreting the results. The data obtained will lead to a better understanding of the origin and evolution of continental crust, and may be able to address the fundamental question of why are silicic magmas produced in some island arc systems and not in others. The University of Costa Rica (UCR) and Michigan State University (MSU) complement each other in their research capabilities. CRU can provide valuable knowledge of the local geology and an understanding of the physical volcanology in the area, and the MSU researchers bring the expertise in chemical petrology and the analytical equipment necessary for in-depth geochemical research. ***