Geochemistry and Petrogenesis of Eocene Potassic Volcanism in the Absaroka Volcanic Field, Wyoming

怀俄明州阿布萨罗卡火山田始新世钾质火山的地球化学和岩石成因

• 批准号: 9725287
• 负责人: Todd Feeley
• 金额: $ 12.5万
• 依托单位: Montana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-06-01 至 2001-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725287&HistoricalAwards=false
• 关键词: Geochemistry; Petrogenesis; Eocene; Potassic; Volcanism

9725287 Feeley This is a proposal designed to carry out a geological and geochemical transect across the northern part of the Absaroka volcanic field, Wyoming. Because the Absaroka volcanic rocks record one of the most voluminous and compositionally diverse magmatic episodes to affect the Cordillera during the Eocene, the results obtained from this study will significantly improve our knowledge of the ages, compositions, and petrogenesis of Tertiary magmatism in the northern Rocky Mountains. This, in turn, will provide insight into the fundamental problem of how rock suites with potentially arc-like calc-alkaline affinities and across-strike geochemical trends can form in such different tectonic environments, and possibly in the absence of contemporaneous subduction. The analytical work will include analysis of major and trace elements by XRF and ICP-MS, analysis of Sr, Nd, and Pb isotopic ratios by TIMS, and mineral analysis by electron microprobe. Overall, this study represents a realistic first approach towards providing a modern petrologic perspective on one of the outstanding unresolved issues in deciphering the Cenozoic geological history of the northwestern United States: namely, the origin of the Absaroka magmatic rocks.

9725287 Feeley这是一项旨在对怀俄明州Absaroka火山区的北方部分进行地质和地球化学横断面调查的建议。 由于Absaroka火山岩记录了始新世期间影响科迪勒拉山脉的最大量和成分多样的岩浆事件之一，因此从这项研究中获得的结果将显着提高我们对北方落基山脉第三纪岩浆活动的年龄，成分和岩石成因的认识。 反过来，这将提供深入了解的基本问题，如何岩石套件与潜在的弧一样的钙碱性亲和力和跨罢工的地球化学趋势可以形成在这样不同的构造环境，并可能在没有同期俯冲。 分析工作将包括通过XRF和ICP-MS进行主量和微量元素分析，通过TIMS进行Sr、Nd和Pb同位素比分析，以及通过电子显微探针进行矿物分析。总的来说，这项研究代表了一个现实的第一种方法，提供了一个现代岩石学的角度来看，在破译美国西北部的新生代地质历史的一个悬而未决的问题：即，Absaroka岩浆岩的起源。