Collaborative Research: An Isotopic and Trace Element Study of Links Between Source Heterogeneity and Mantle Melting Beneath the Southeast Indian Ridge

合作研究：东南印度洋中脊下方源异质性与地幔融化之间联系的同位素和微量元素研究

• 批准号: 1357036
• 负责人: Barry Hanan
• 金额: $ 12.67万
• 依托单位: San Diego State University Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1357036&HistoricalAwards=false
• 关键词: Collaborative; Research; Isotopic; Trace; Element

The Southeast Indian ridge is a mid-ocean spreading center that lies between Australia and Antarctica. Due to its location, it is one of the least sampled and studied parts of the ocean floor. It is also where French oceanographic cruises have recently sampled a large number of closely-spaced mid-ocean ridge spreading center lavas in an effort to examine geochemical heterogeneity of the mantle on a fine scale. This research teams US scientists from San Diego State University and Oregon State University with scientists from two major French academic oceanographic institutions to carry out a comprehensive geochemical study of these lavas to help understand the crust below the Indian Ocean and how it is affected by the transfer of mantle material. Research goals are to examine the validity of a risky, new hypothesis, based on statistical analysis and theory, which proposes that mantle heterogeneity is bimodal in character and represented by streak-like chemical differences that can help us understand mantle convection and the chemical differentiation of the Earth. The US component of the work involves the analysis of radiogenic isotopes (Pb, Nd, Sr, and Hf) and trace element geochemical analyses of Southeast Indian Ridge basalt glasses. These data will be used to determine whether the streak-like Pb and Hf isotopes beneath the Southeast Indian Ridge propagate across the area, (2) investigate whether mid-ocen ridge basalt lava isotopic heterogeneity is different in the vicinity of active hotspot areas compared with those that are far from hotspots, and (3) investigate how isotopic heterogeneity relates to changes in mantle source lithology and partial melting conditions. Broader impacts of the proposal are good and involve strong international collaboration with scientists at two major French oceanographic academic institutions. The project will also help support an NSF-funded, open, isotope facility at San Diego State University and will develop, in conjunction with French colleagues, improved volcanic glass dissolution procedures, thereby building infrastructure for science. Additional impacts include undergraduate training and incorporation of research results into college student coursework.

东南印度洋脊是位于澳大利亚和南极洲之间的大洋中部扩张中心。由于它的位置，它是海底采样和研究最少的部分之一。法国的海洋巡洋舰最近也在这里对大量间隔紧密的洋中脊扩张中心熔岩进行了取样，以便在精细的尺度上检验地幔的地球化学异质性。这项研究将来自圣地亚哥州立大学和俄勒冈州立大学的美国科学家与来自法国两家主要学术海洋学机构的科学家联合起来，对这些熔岩进行全面的地球化学研究，以帮助了解印度洋下方的地壳以及它是如何受到地幔物质转移的影响的。研究目标是检验一个基于统计分析和理论的冒险的新假设的有效性，该假设提出地幔非均质性具有双峰性，并以条纹状化学差异为代表，可以帮助我们理解地幔对流和地球的化学分异。美国部分的工作涉及放射性成因同位素（Pb、Nd、Sr和Hf）的分析和东南印度岭玄武岩玻璃的微量元素地球化学分析。这些数据将用于确定东南印度洋脊下的条状Pb和Hf同位素是否在整个区域内传播，(2)研究洋中脊玄武岩熔岩同位素非均质性在活动热点区域附近与远离热点区域是否存在差异，(3)研究同位素非均质性与地幔源岩性和部分熔融条件的变化之间的关系。该提案的广泛影响是好的，并涉及与法国两大海洋学学术机构的科学家进行强有力的国际合作。该项目还将帮助支持美国国家科学基金会在圣地亚哥州立大学资助的一个开放的同位素设施，并将与法国同事一起开发改进的火山玻璃溶解程序，从而为科学建设基础设施。其他影响还包括本科生培训和将研究成果纳入大学生课程。