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

9304102怀特这是康奈尔大学和布朗大学的合作项目。我们建议通过多学科的方法研究圣卢西亚、圣文森特和格林纳达的岩浆成因和演化，包括野外工作、岩石学研究、常量元素、微量元素、锶、钕、铅和氧同位素测定以及K-Ar定年。岩石学研究将包括微探针和激光烧蚀-电感耦合等离子体质谱研究。这项研究的近期目标是：(1)确定弧壳对格林纳达和圣卢西亚地幔岩浆演化的贡献，(2)利用这些岩浆中最具镁质的岩浆--其中一些岩浆自地幔楔体产生以来仅略有演化--来研究熔融程度和来源富集度，以及(3)确定这些岛屿上的岩浆成分随时间发生了怎样的变化。实现这些目标使我们能够处理几个更广泛的目标。它们是：(1)岛弧中岩浆的形成和演化过程，(2)加勒比地区的构造演化，(3)地壳同化发生或不发生的必要条件，(4)从俯冲板块到岛弧岩浆的物质输运，以及(5)从俯冲带到深部地幔的不相容元素的质量通量。通过专注于少数几个拥有完善的实验知识库的地方，并拥有广泛的数据，我们相信我们可以大幅改进早期的模型。***

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. ***