A Comparative Elemental and Isotopic Study of Seawater Component Assimilation on the East Pacific Rise (EPR) Using Volatiles, Halogens, Boron and Lithium

使用挥发物、卤素、硼和锂对东太平洋海隆 (EPR) 海水成分同化进行比较元素和同位素研究

• 批准号: 9907174
• 负责人: Steven Shirey
• 金额: $ 19.82万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-11-01 至 2003-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907174&HistoricalAwards=false
• 关键词: Comparative; Elemental; Isotopic; Study; Seawater

An ion microprobe (secondary ion mass spectrometer) study of the halogens (Cl, F), volatiles (CO2, H2O, S), light elements (B, Li) and their relevant isotopic compositions (7Li/6Li, 11B/10B, 34S/32S and 37Cl/35Cl) will be carried out on well-characterized East Pacific Rise (EPR) glasses from the 9 degrees N, 12 degrees N, and 15-16degrees N regions. Assimilation of seawater components into basaltic magma along the global ocean ridge system may be more widespread than is commonly assumed. At fast-spreading ridges such as the EPR where axial magma chambers are well-defined, this process may be ubiquitous. There is currently a poor understanding of the seawater-component assimilation process on the local spatial scale of volcanic features and petrologic segmentation. This work will use different geochemical tools, each with its own response to the assimilation process and look at segments of the ridge system where small differences in spreading rate, volcanic edifice, lithospheric structure and axial magma chamber morphology can be recognized. The purpose of this study is to determine how and where seawater component assimilation occurs in the oceanic lithosphere, to relate differences in the extent of this process to volcanic and morphologic features of the oceanic ridge system.

利用离子探针（二次离子质谱仪）对9°N、12°N和15-16°N区域的卤素（Cl、F）、挥发物（CO2、H2O、S）、轻元素（B、Li）及其相关同位素组成（7Li/6Li、11B/10B、34S/32S和37Cl/35Cl）进行了研究。海水成分沿全球洋脊系统向玄武岩岩浆的同化可能比通常假设的更为普遍。在像EPR这样快速扩张的山脊上，轴向岩浆房很明确，这个过程可能无处不在。目前对火山特征和岩石学分割在局部空间尺度上的海水组分同化过程了解甚少。这项工作将使用不同的地球化学工具，每种工具对同化过程都有自己的反应，并研究山脊系统的各个部分，在那里可以识别出扩张速度、火山大厦、岩石圈结构和轴向岩浆室形态的微小差异。本研究的目的是确定海洋岩石圈中海水成分同化发生的方式和位置，并将这一过程的程度差异与海洋脊系统的火山和形态特征联系起来。