STABLE ISOTOPE SYSTEMATICS OF MANTLE PERIDOTITES IN THE CONTEXT OF THEIR TECTONIC HISTORY

地幔橄榄岩在其构造历史背景下的稳定同位素系统

• 批准号: 8708494
• 负责人: Russell Harmon
• 金额: $ 7万
• 依托单位: Southern Methodist University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-06-01 至 1989-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8708494&HistoricalAwards=false
• 关键词: STABLE; ISOTOPE; SYSTEMATICS; MANTLE; PERIDOTITES

It is generally agreed that fluids play a critical role in mantle enrichment processes and that mantle enrichment events frequently are superimposed in a complex manner on peridotitic mantle that has been depleted in incompatible trace elements and light rare- earth elements through prior partial melting. Chemical and radiogenic isotope data suggest that such metasomatic fluids may be derived, in part, from recycled crustal materials and that some form of fluid metasomatism may be a necessary precursor to intraplate alkalic magmatism. Stable isotope studies provide a unique means of addressing mantle heterogeneity and enrichment/depletion processes because, 1) oxygen is a major element in terms of its behavior, whereas hydrogen is a trace element that is concentrated in aqueous fluid phases, and 2) the mantle has been shown to be heterogeneous in terms of both its O- and H-isotope compositions. This project will undertake a detailed stable isotope study of four regions in which mantle peridotites of distinctly different petrological, chemical, and radiogenic isotope character have been erupted in Late Tertiary to Recent alkalic basalts. The four gerions also are characterized by having sub-continental lithospheric mantle with differing tectonic histories. The focus of the research is an understanding of the causes of stable isotope variations in the different types of peridotites present within each region, and a comparison of the isotope systematics of peridotites from the four gegions in the context of their different tectonic histories.

流体在地幔中起着至关重要的作用 地幔富集事件频繁发生， 以复杂的方式叠加在橄榄岩地幔上， 已经耗尽了不相容的微量元素和轻稀土 地球元素通过预先部分熔化。 化学和 放射性同位素数据表明，这种交代流体可能 部分来自回收的地壳材料， 某些形式流体交代作用可能是 板内碱性岩浆作用 稳定同位素研究提供了一种独特的手段， 地幔不均匀性和富集/贫化过程， 1)氧在其行为方面是主要元素，而 氢是一种微量元素， （2）地幔已被证明是不均匀的， 它的氧和氢同位素组成。 这个项目 将对四个区域进行详细的稳定同位素研究， 这些地幔橄榄岩具有明显不同的岩石学特征， 化学和放射性同位素特征已经爆发， 晚第三纪至现代碱性玄武岩。 这四位老人还 其特征是具有陆下岩石圈地幔 地质构造历史不同 研究的重点是 了解稳定同位素变化的原因， 每个区域内存在不同类型的橄榄岩， 并对1998 - 1999年的橄榄岩同位素系统学进行了比较 不同构造背景下的四个地区 历史