RUI: Crystallization and Differentiation in a Sheet-like Magma Chamber: An Integrated Study of the Graveyard Point Sill, Eastern Oregon

9304102白色这是康奈尔大学和布朗大学之间的一个合作项目。我们建议通过多学科的方法，包括野外工作，岩相学研究，主要元素，微量元素，Sr，Nd，Pb和O同位素测定，和K-Ar定年研究岩浆的成因和演化在圣卢西亚，圣文森特和格林纳达。岩相学研究将包括微探针和激光烧蚀感应耦合等离子体质谱研究。本研究的近期目标是：（1）确定弧壳对格林纳达和圣卢西亚幔源岩浆演化的贡献，（2）利用这些岩浆中最具镁性的岩浆，其中一些自地幔楔中产生以来仅轻微演化，来研究熔融和源富集的程度，以及（3）确定这些岛屿上岩浆成分如何随时间变化。实现这些目标使我们能够实现几个更广泛的目标。这些措施是：提高了对以下方面的认识：（1）岛弧中岩浆的生成和演化过程;（2）加勒比区域的构造演化;（3）地壳同化发生或不发生的必要条件;（4）从俯冲板片到岛弧岩浆的物质迁移;（5）从俯冲带到地幔深部的不相容元素的物质通量。通过专注于一些具有改进的实验知识基础的地方，并拥有广泛的数据，我们相信我们可以大大改进早期的模型。***

9304102 White This is a collaborative project between Cornell and Brown Universities. We propose to study magma genesis and evolution in St. Lucia, St. Vincent, and Grenada through a multi-disciplinary approach that will include field work, petrographic study, major element, trace element, Sr, Nd, Pb and O isotope determination, and K-Ar dating. Petrographic study will include both micro probe and laser-ablation- inductively-coupled-plasma-mass-spectrometry studies. The immediate objectives of this study are to: (1) determine the contribution of arc crust to the evolution of mantle- derived magmas in Grenada and St. Lucia, (2) use the most magnesian of these magmas, some of which are only slightly evolved since production in the mantle wedge, to investigate degree of melting and source enrichment, and (3) determine how magma composition has changed through time on these islands. Achieving these objectives allows us to address several broader objectives. These are: enhanced understanding of (1) magma generation and evolution processes in island arcs, (2) tectonic evolution of the Caribbean region, (3) the conditions necessary for crustal assimilation to occur or not to occur, (4) mass transport from the subducting slab to island arc magmas, and (5) mass fluxes of incompatible elements to the deep mantle from subduction zones. By focusing on a few localities with an improved experimental knowledge base, and having a wide range of data, we believe we can substantially improve earlier models. ***