Isotopic Studies of Madagascan Basalts and Deccan Picritic Lavas

马达加斯加玄武岩和德干苦味质熔岩的同位素研究

• 批准号: 9104897
• 负责人: John Mahoney
• 金额: $ 10.58万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-06-01 至 1994-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9104897&HistoricalAwards=false
• 关键词: Isotopic; Studies; Madagascan; Basalts; Deccan

This is a two-part project to continue investigation of the sources and petrogenesis of Cretaceous flood basalts in Madagascar and the Deccan Traps of India. It is proposed to complete study of Madagascan lavas and dikes, conducted in collaboration with A. Saunders and M. Storey (U. Leicester, U.K.). Specifically the plan is: (a) to continue Nd, Pb, and Sr isotopic analysis of a subset of 300 well-documented samples; (b) for Mahoney to contribute to a planned 1991 field trip to the major remaining exposures in northern Madagascar; and (c) to conduct isotopic work on selected samples therefrom. The second focus of the proposed work is an isotopic (Pb, Nd, Sr) study of a unique collection of near-primary picritic lavas and associated basalts in the northern Deccan Traps. These samples are markedly enriched in highly incompatible elements compared to the Western Ghats formations. However, their incompatible element patterns suggest that some are likely to be affected little by continental material. Also, because they may represent some of the earliest eruptions in the Deccan, the plan is to obtain high-quality 40Ar-39Ar dates (from R. Duncan, OSU).

这是一个由两部分组成的项目，旨在继续调查马达加斯加和印度德干地盾白垩纪溢流玄武岩的来源和岩石成因。 建议与 A. Saunders 和 M. Storey（英国莱斯特大学）合作完成对马达加斯加熔岩和堤坝的研究。 具体计划是： (a) 继续对 300 个有据可查的样品的子集进行 Nd、Pb 和 Sr 同位素分析； (b) 马奥尼为计划于 1991 年对马达加斯加北部剩余的主要暴露进行实地考察作出贡献； (c) 对从中选定的样品进行同位素工作。 拟议工作的第二个重点是对德干地盾北部独特的近原生苦苦味熔岩和相关玄武岩集合进行同位素（Pb、Nd、Sr）研究。 与西高止山脉地层相比，这些样品明显富含高度不相容的元素。 然而，它们不相容的元素模式表明，其中一些可能受到大陆物质的影响很小。 此外，由于它们可能代表了德干地区最早的一些喷发，因此计划获取高质量的 40Ar-39Ar 数据（来自俄勒冈州立大学的 R. Duncan）。