Collaborative Research: Combined Electron/Ion Microprobe Study of the Composition of the Deep Continental LithosphereBeneath the Colorado Plateau and Adjoining Regions

该项目将重点放在科罗拉多高原和邻近地区，在那里，推断的元古界橄榄岩根延伸到大约80-100公里深，并被裂隙的大陆岩石圈包围。在科罗拉多高原内外的火山岩中产出了丰富的上地幔样品，这些包体中的一些矿物相记录了岩石圈的现代成分历史。矿物相的微量元素丰度(REE、Ti、Zr、Hf、Sr)将被用来推断岩石圈整体成分在垂直和横向上的变化、最近岩浆或交代事件中所涉及的相的性质、与这些事件相一致的任何微量元素分馏的性质(例如，REE/HFSe)、以及根据分区轮廓的建模来确定这些事件的时间。主要的分析工具将是用于现场分析痕量和常量元素的离子和电子微探针。

This project will focus on the Colorado Plateau and adjoining regions where an inferred Proterozoic-aged, peridotite root extends to a depth of approximately 80-100 km and is surrounded by rifted continental lithosphere. Abundant samples of the upper mantle occur in volcanic rocks on and off the Colorado Plateau, and some mineral phases in these xenoliths record the recent compositional history of the lithosphere. Trace element abundances (REE,Ti,Zr,Hf,Sr) of mineral phases will be used to deduce the variation in the bulk composition of the lithosphere vertically and laterally, the nature of the phases involved in recent magmatic or metasomatic events, the nature of any trace element fractionations (e.g., REE/HFSE) coincident with these events, and the timing of these events from modelling of zoning profiles. Principal analytical tools will be the ion and electron microprobes for in situ analysis of trace and major elements.