Melt Generation Below Continents in Diffuse Igneous Provinces

大陆下方弥漫火成岩省的熔融生成

• 批准号: 0917651
• 负责人: Haibo Zou
• 金额: $ 7.14万
• 依托单位: Auburn University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0917651&HistoricalAwards=false
• 关键词: Melt; Generation; Below; Continents; Diffuse

Intellectual merit. A comprehensive uranium-series (U-series) isotope study is proposed to understand the origins of young (10,000 years, or, 10 kyr) continental lavas from East Asia. Widely dispersed intraplate volcanism in East Asia is distinct from large-volume basaltic eruptions at Large Igneous Provinces by virtue of its greater compositional diversity, lower rate of melt production, and lack of evidence for deep mantle plumes. Preliminary U-Th disequilibrium data of the young lavas from East Asia suggest that the young lavas from East China display significant 230Th excesses whereas the young lavas from SE Tibet show strong 238U excesses. We propose to analyze U-Th disequilibrium in additional samples to test the generality of these results. U-Pa and Th-Ra disequilibria, together with Nd, Sr and Pb isotopic compositions and trace element concentrations, will also be measured. Modelling of these data will help constrain process of melt generation and transportation. The proposed research addresses fundamental questions concerning the mechanisms of melt generation below continents in diffuse igneous provinces, and specifically the relative roles of lithosphere and asthenosphere mantle sources in the context of active geodynamic settings in East China and SE Tibet.Broader impacts. These include collaborations between UCLA, WHOI, and Chinese Bureau of Seismology. Secondly, this project will support the research of an early-career principal investigator, and would foster the educational development of one or two UCLA undergraduates. Third, quantitative geochemical models developed from the project are going to be available to the community of petrology and geochemistry.

智力上的优点。建议进行一项全面的铀系（U系）同位素研究，以了解东亚年轻（1万年，或1万年）大陆熔岩的起源。广泛分布在东亚的板内火山活动与大火成岩省的大量玄武岩喷发不同，因为它们具有更大的成分多样性、更低的熔体产生速率以及缺乏深部地幔柱的证据。东亚年轻熔岩的初步U-Th不平衡数据表明，中国东部的年轻熔岩显示出明显的230 Th过量，而西藏东南部的年轻熔岩则显示出强烈的238 U过量。我们建议在额外的样本中分析U-Th不平衡，以测试这些结果的一般性。还将测量U-Pa和Th-Ra不平衡，以及Nd、Sr和Pb同位素组成和微量元素浓度。这些数据的建模将有助于限制熔体的产生和输送过程。该研究解决了有关大陆下扩散火成岩省熔体生成机制的基本问题，特别是在中国东部和西藏东南部活跃的地球动力学背景下岩石圈和软流圈地幔源的相对作用。其中包括UCLA、WHOI和中国地震局之间的合作。其次，这个项目将支持一个早期职业生涯的首席研究员的研究，并将促进一个或两个加州大学洛杉矶分校本科生的教育发展。第三，该项目开发的定量地球化学模型将可供岩石学和地球化学界使用。