The Petrogenesis of Cr-Poor and Cr-Rich "Megacrysts" in Mantle-Derived, Silica-Undersaturated Magmas

幔源二氧化硅不饱和岩浆中贫铬和富铬“巨晶体”的岩石成因

• 批准号: 9118128
• 负责人: Clive Neal
• 金额: $ 7.82万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-03-15 至 1994-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9118128&HistoricalAwards=false
• 关键词: Petrogenesis; Cr; Poor; Rich; Megacrysts

The purpose of this research is to undertake a detailed geochemical examination of megacrysts suites from the Malaitan alnoite (Solomon Islands), and the Sloan-Nix kimberlite (Colorado). Samples will be gathered from existing collections and initially characterized by EMP analysis. Fractionation trends thus defined will allow critical samples to be selected for IMP analysis. Traverses will be carried out on samples forming end-member compositions to the apparent fractionation trends defined by EMP analyses. This approach will then pin-point samples for isotopic analysis (Sr, Nd, Pb, O), using micro-sampling techniques to investigate potential isotopic zonation within and between megacrysts. This integrated approach is required to: 1) determine the nature of the parental magma; 2) evaluate the mode of crystallization within the mantle regime; 3) determine whether the proposed igneous fractionation occurred in an open- or closed-system environment; 4) establish any link between megacryst crystallization and metasomatic processes; and 5) examine the relationship (if any) between Cr-rich and Cr- poor megacrysts.

这项研究的目的是对Malaitan Alnoite（所罗门群岛）和Sloan-Nix-Nix Kimberlite（Colorado）进行详细的地球化学检查。 样本将从现有的集合中收集，并最初以EMP分析为特征。 因此，定义的分馏趋势将允许选择关键样品进行IMP分析。 遍历将对形成末端成员组成的样品进行，以表明由EMP分析定义的明显分级趋势。 然后，这种方法将使用微采样技术来研究同位素分析（SR，ND，PB，O）的固定点样品，以研究Megacrysts内部和之间的潜在同位素分区。 需要这种综合方法：1）确定父母岩浆的性质； 2）评估地幔方案内的结晶模式； 3）确定所提出的火成分分馏是否发生在开放或封闭系统环境中； 4）建立巨晶结晶与代理过程之间的任何联系； 5）检查Cr-rich和Cr-Cr-cr-megacrysts之间的关系（如果有的话）。