Collaborative Research: Flood Basalt Magma Genesis and Dynamics: Application of Crystal Isotope Stratigraphy and Igneous Componentry to the Columbia River Basalt Group

合作研究：溢流玄武岩岩浆成因和动力学：晶体同位素地层学和火成岩成分在哥伦比亚河玄武岩群中的应用

• 批准号: 0440336
• 负责人: John Wolff
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0440336&HistoricalAwards=false
• 关键词: Collaborative; Research; Flood; Basalt; Magma

Continental flood basalts are the products of events in which very large volumes of magma (105 - 107 km3) are erupted in geologically short periods of time (=106 years). Although there is widespread agreement that rising deep-rooted mantle plumes provide the heat source for such intense volcanism, other mantle and crustal rocks may melt under the thermal impact of the plume to contribute some, perhaps most, of the total erupted mass of flood basalt. Assessing the relative contributions of magma from these different sources to continental flood basalt lavas is a long-standing problem. This project will apply modern approaches of small-scale sampling, targeting key geochemical tracers (chiefly isotope ratios) within and between single crystals and basalt matrix, to the Columbia River flood basalts. Because this approach is based on rock textures that grow sequentially, this research will enable reconstruction of how and in what order the magmas were assembled from different sources. In addition, residence times of crystals in their host magmas can be obtained by diffusion modeling of spatial variations in isotope abundance ratios in crystals, allowing constraints to be placed on the durations of individual eruptions, which is an important parameter in assessing the potential these events have for global climate and ecological disruption. Over the next few years, the techniques to be employed will enter the mainstream of geochemical investigations into volcanism, and training research students to meet this need is a further benefit of the project.

大陆溢流玄武岩是在地质上很短的时间(=106年)内喷发大量岩浆(105-107千米~3)的产物。尽管人们普遍认为，上升的深地幔热柱为如此强烈的火山活动提供了热源，但其他地幔和地壳岩石可能会在热柱的热影响下熔融，贡献部分，也许是全部喷发的溢流玄武岩质量的大部分。评估这些不同来源的岩浆对大陆溢流玄武岩熔岩的相对贡献是一个长期存在的问题。该项目将对哥伦比亚河泛滥玄武岩应用现代小规模采样方法，目标是单晶和玄武岩基质内部和之间的关键地球化学示踪剂(主要是同位素比率)。因为这种方法是基于连续生长的岩石结构，所以这项研究将能够重建岩浆是如何以及以什么顺序从不同的来源聚集在一起的。此外，通过对晶体中同位素丰度比的空间变化进行扩散模拟，可以获得晶体在其宿主岩浆中的停留时间，从而对个别喷发的持续时间施加限制，这是评估这些事件对全球气候和生态破坏的潜力的一个重要参数。在接下来的几年里，将采用的技术将进入火山作用地球化学调查的主流，培训研究学生以满足这一需求是该项目的进一步好处。