Multiple Approaches to Study of the Hafnium Isotope Evolution of the Crust and Mantle: 4.3 b.y. ago to Present

研究地壳和地幔铪同位素演化的多种方法：4.3 b.y.

• 批准号: 9304455
• 负责人: Clark Johnson
• 金额: $ 14万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-07-15 至 1995-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9304455&HistoricalAwards=false
• 关键词: Multiple; Approaches; Study; Hafnium; Isotope

The proposed work involves three parts aimed at the study of crust-mantle evolution from 4.3 Ga to present, all of which use Hafnium isotope variations as the common theme. The projects we have chosen reflect a balance between identification of key localities and sample suites and areas of research in which the PI and Co-PI have extensive experience. Our investigations of the sub-continental mantle focus on sites which represent major, rapidly- developed thermal anomalies in the mantle that involved various contributions from plume, depleted mantle, and lithospheric mantle. Work on the earliest differentiation of the Earth concentrates on integrated Nd, Hf, and U/Pb isotope work on the oldest terrestrial materials: 4.3 to 4.0 Ga zircons from western Australia and the 4.0 Ga Acasta Gneiss, NWT Canada. Investigations of crust-mantle recycling focus on the Penokean Orogen in Wisconsin through whole-rock/mineral Nd and Pb and combined Nd, Hf, and U/Pb isotope analysis of inherited, Proterozoic, and Archean zircons. This work represents a collaborative effort with 11 other researchers at seven institutions.

本研究分为三部分，以4.3 Ga至今的地壳-地幔演化为研究对象，均以铪同位素变化为共同主题。我们选择的项目反映了在确定关键地点和样本套件以及PI和Co-PI拥有丰富经验的研究领域之间的平衡。我们对次大陆地幔的研究集中在代表地幔中主要的、快速发展的热异常的地点，这些异常涉及来自地幔柱、枯竭地幔和岩石圈地幔的各种贡献。地球最早分异的工作主要集中在最古老陆地物质（西澳大利亚4.3 ~ 4.0 Ga锆石和加拿大NWT 4.0 Ga Acasta片麻岩）的Nd、Hf和U/Pb同位素综合工作上。通过对继承锆石、元古代锆石和太古代锆石的Nd、Hf和U/Pb组合同位素分析，研究了威斯康星Penokean造山带壳幔再循环。这项工作是与七个机构的其他11名研究人员共同努力的结果。