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

与一位墨西哥同事合作，PIS正在对墨西哥中部最南端盆地和山脉省(BRP)的一条横断面上的中新世到最近的火山岩进行综合的地质、岩石学和地球化学研究。该计划将通过对来自地幔的尖晶石二辉橄榄岩包体进行全面的岩石学和地球化学研究，将这项工作扩展到样带地区。全岩样品和成分矿物的常量元素分析将使PI能够评估作为可育橄榄岩地幔部分熔融残留物的包体的岩石成因模式，并评估上地幔成分、温度、氧逸度和熔体提取程度的区域差异。他们还计划对单斜辉石中的锶-钕-铅同位素比值和微量元素丰度进行详细研究，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作用，如与第三纪俯冲事件有关的交代作用和与正在进行的岩石圈伸展有关的作用。

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.