Collaborative Research: Sr-Nd-Pb-Hf Isotope Studies of Deep Crustal Xenoliths from the Southwestern U.S.A. and Northern Mexico

9318687卡梅隆研究人员建议对德克萨斯州西部戴维斯山脉-大弯曲地区和墨西哥奇瓦瓦州的Camargo玄武岩区的麻粒岩相捕虏体进行岩石学、地球化学、Sr-Nd-Pb-Hf同位素和常规U/Pb锆石研究。 此外，他们还将分析来自新墨西哥州基尔本霍尔的含石榴石变火成残积岩的铪同位素组成。 基尔本洞和其他地方的Restites只有有限的变化 Nd（0），但176 Lu/177 Hf比值范围很广，包括极值（0.5）。 含石榴子石残积岩熔融提取的Hf模式年龄应远比基于Nd的模式年龄更明确。 这将是第一次系统研究下地壳捕虏体，整合Sr，Nd，Pb和Hf同位素，这将是迄今为止最详细的常规U/Pb锆石研究。 虽然这项合作努力的直接目标是研究下地壳，但U.C.圣克鲁斯的工人将在华盛顿大学获得宝贵的经验。麦迪逊在国家的最先进的铪同位素分析，包括联合开发新的标准和尖峰。 这种方法将使U.C.圣克鲁斯有效地启动了一个项目，在铪同位素工作。

9318687 Cameron The PIs propose to make a combined petrologic, geochemical, Sr-Nd-Pb-Hf isotope and conventional U/Pb zircon study of granulite facies xenoliths from the Davis Mountains-Big Bend region of west Texas and the Camargo basalt field in Chihuahua, Mexico. In addition, they will analyze garnet- bearing metaigneous restites from Kilbourne Hole, New Mexico, for their Hf isotope compositions. Restites from Kilbourne Hole and the other locations have only limited variation in Nd(0) but a wide range of 176Lu/177Hf ratios including extreme values (0.5). Hf model ages for melt-extraction from garnet-bearing restites should be far less ambiguous than model ages based on Nd. This will be the first systematic study of lower crustal xenoliths that integrates Sr, Nd, Pb, and Hf isotopes, and it will be by far the most detailed conventional U/Pb zircon study to date. Although the immediate goal of this collaborative effort is the study of the lower crust, U.C. Santa Cruz workers will gain valuable experience at U.W. Madison in state-of-the-art Hf isotope analysis, including joint development of new standards and spikes. This approach will allow U.C. Santa Cruz to efficiently start-up a program in Hf isotope work.