Mantle Evolution, Mineral Kinetics, and Tectonics

将对美国西南部的捕虏体进行分析，以研究地幔岩石圈的成分和热演化，以及地幔性质与地壳构造的关系。织构和成分梯度的表征将与薄片的电子探针和PIXE分析以及矿物分离的同位素分析相结合。科罗拉多高原大峡谷地区的捕虏体将得到最详细的研究。这些样品的成分和热历史将与盆地和山脉省的捕虏体进行比较，以了解地壳抬升和伸展与地幔动力学的关系。大峡谷包体中的结构和锶-钕系统学是不寻常的，它们的特征将被用来理解可能与俯冲有关的交代过程。最近从中部高原的纳瓦霍油田采集了大量样品，并将对精选样品进行分析，以确定地幔水化和榴辉岩相重结晶的深度和时间。在研究的所有部分，将通过对梯度的仔细分析和数值模拟，特别努力阐明地幔中的输送过程和矿物平衡速率。

Xenoliths from the southwestern U.S. will be analyzed to study the compositional and thermal evolution of mantle lithosphere and the relationships between mantle properties and crustal tectonics. Characterization of textures and compositional gradients will be combined with electron microprobe and PIXE analysis of thin sections and with isotopic analysis of mineral separates. Xenoliths from the Grand Canyon field on the Colorado Plateau will be studied in most detail. Compositions and thermal histories of the samples will be compared to those of xenoliths from the Basin and Range province, to learn how crustal uplift and extension are related to mantle dynamics. Textures and Sr- Nd systematics in the Grand Canyon xenoliths are unusual, and they will be characterized to understand metasomatic processes that may be subduction-related. A large collection from the Navajo field in the central Plateau has been recently acquired, and choice samples will be analyzed to determine depth and timing of mantle hydration and eclogite-facies recrystallization. In all parts of the study, particular effort will be made to elucidate transport processes and rates of mineral equilibration in the mantle, by careful analyses of gradients and by numerical simulations.