Oxygen isotope variations in oceanic magmatic rock suites: assimilation-fractional crystallization processes versus mantle source variations

大洋岩浆岩组中的氧同位素变化：同化分异结晶过程与地幔源变化

• 批准号: 84784881
• 负责人: Professor Dr. Karsten Matthias Haase
• 金额: --
• 依托单位: Forschungsschwerpunkt Krustendynamik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/84784881?language=en
• 关键词: Oxygen; isotope; variations; oceanic; magmatic

Oxygen isotopes are an important tool to study reactions between ascending mantle-derived magmas and material in the oceanic lithosphere that has been altered by surface processes like for example, sediments or hydrothermally altered rocks. Furthermore, crystal fractionation processes can also affect the O isotope composition especially of evolved magmas because different mineral phases fractionate O isotopes. Both assimilation and crystal fractionation thus impede the study of O isotope compositions of the magma sources in the mantle which could give important insights into recycling processes at subduction zones and in deep mantle plume-derived intraplate magmas. Here we suggest a study of the O isotope variation of five well-characterized lava series from different oceanic magmatic settings (mid-ocean ridge, oceanic intraplate, back-arc, and island arc settings) in order to define the variations between basaltic and silicic lavas and the processes affecting the O isotope ratios. Based on the understanding of lithospheric processes we will be able to distinguish the O isotope composition of the mantle sources of the magmas and draw conclusions on crustal recycling into the deep mantle and into the mantle wedge beneath subduction zones.

氧同位素是研究上升的幔源岩浆与海洋岩石圈中被表面过程改变的物质（例如沉积物或热液蚀变岩石）之间反应的重要工具。此外，由于不同矿物相对氧同位素的分馏作用，晶体分馏作用也会影响岩浆的氧同位素组成。同化和晶体分馏，从而阻碍了O同位素组成的地幔中的岩浆源，这可能会给重要的见解再循环过程中的俯冲带和深地幔柱衍生板内岩浆的研究。在这里，我们建议从不同的大洋岩浆环境（洋中脊，大洋板内，弧后，岛弧设置）的五个良好的特点熔岩系列的O同位素变化的研究，以确定玄武岩和玄武岩之间的变化和影响的O同位素比值的过程。基于对岩石圈过程的认识，我们将能够区分岩浆的地幔源的O同位素组成，并得出地壳再循环进入深地幔和俯冲带下的地幔楔的结论。

项目成果

Oxygen isotope evidence for the formation of silicic Kermadec island arc and Havre-Lau backarc magmas by fractional crystallisation

• DOI: 10.1016/j.epsl.2011.07.014
• 发表时间: 2011-09
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: K. Haase;S. Krumm;M. Regelous;M. Joachimski