Tracing subducted crust in the oceanic mantle with siderophile elements and transition metal stable isotopes and implications for the sources of basaltic volcanism

用亲铁元素和过渡金属稳定同位素追踪大洋地幔中的俯冲地壳及其对玄武岩火山活动来源的影响

• 批准号: 277251666
• 负责人: Professorin Dr. Ambre Luguet, since 11/2016
• 金额: --
• 依托单位: Department of Earth Sciences
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/277251666?language=en
• 关键词: Tracing; subducted; crust; oceanic; mantle

In order to understand global material fluxes between crust and mantle, the fate of subducted oceanic crust and its contribution to mantle-derived volcanism needs to be constrained. Pyroxenites have been suggested to be products of interaction of melts derived from subducted crust and to be an important component in the source region of oceanic basalts in the lithosphere. To develop a more complete understanding of the processes controlling the distribution of tracers during melt-rock interaction, a combined study of highly siderophile elements (HSE, including Os isotopes) and stable isotopes of transition metals (Fe, Cu, Ni) on both the whole rock and individual grain scale in pyroxenite layers and their immediate surroundings is proposed. Pyroxenites from the External Ligurides, Italy, which have been demonstrated to contain crust-derived material, are ideally suited for this type of study. Highly siderophile elements and stable isotopes of Fe have been developed as useful tools to study interaction of melts with surrounding wall rock in the mantle, and coupled with development of Ni and Cu isotopes as mantle tracers will provide new insights about the distribution of sulfide-hosted elements during melt-rock interaction.

为了了解全球地壳和地幔之间的物质通量，俯冲洋壳的命运及其对幔源火山作用的贡献需要加以限制。辉石岩是俯冲壳源熔体相互作用的产物，是大洋玄武岩源区岩石圈的重要组成部分。为了更全面地了解熔体-岩石相互作用过程中示踪剂分布的控制过程，建议在辉石岩层及其周围环境中进行全岩和单个颗粒尺度上的高亲铁元素（HSE，包括Os同位素）和过渡金属（Fe，Cu，Ni）稳定同位素的联合研究。来自意大利外利古里季斯的辉石已被证明含有结壳衍生物质，非常适合这类研究。高亲铁性元素和Fe稳定同位素已成为研究地幔熔体与围岩相互作用的有效工具，而Ni和Cu同位素作为地幔示踪剂的发展将为研究熔体-岩石相互作用过程中硫化物赋存元素的分布提供新的认识。