Petrology and Geochemistry of Spinel-Peridotite Xenoliths from Central Mexico: Mantle Domains and Processes

在与一位墨西哥同事的合作下，pi正在对来自墨西哥中部最南端盆地和山脉省（BRP）的一个样带的中新世至近代火山岩进行综合地质、岩石学和地球化学研究。计划将这项工作扩展到样带地区，对地幔源尖晶石-辉橄榄岩捕虏体进行全面的岩石学和地球化学研究。对整个岩石样品和组成矿物的主元素分析将使pi能够评估捕虏体作为肥沃橄榄岩地幔部分熔融残留物的岩石成因模型，并评估上地幔成分、温度、氧逸度和熔融萃取程度的区域差异。他们还计划对斜辉石中Sr-Nd-Pb同位素比率和微量元素丰度进行详细的研究，这将使他们能够研究流体/熔体对上地幔地球化学的复杂交代变化，例如与第三纪俯冲事件有关的变化和与正在进行的岩石圈伸展有关的变化。

In collaboration with a Mexican colleague the PIs are conducting an integrated geological, petrological, and geochemical study of Miocene to Recent volcanic rocks from a transect across the southernmost Basin and Range Province (BRP) of central Mexico. The plan is to extend this work in the transect area by conducting a comprehensive petrological and geochemical study of mantle-derived spinel-lherzolite xenoliths. Major-element analyses of whole-rock samples and constituent minerals will enable the PIs to evaluate petrogenetic models for the xenoliths as residues of partial melting of fertile peridotitic mantle and to evaluate regional differences in upper-mantle composition, temperature, oxygen fugacity, and degree of melt extraction. They also plan to conduct detailed studies of Sr-Nd-Pb isotopic ratios and trace-element abundances in clinopyroxenes, which will allow them to investigate complex metasomatic modifications of the upper-mantle geochemistry by fluid/melts, such as those related to the Tertiary subduction event and those related to on- going lithospheric extension.