夏威夷复苏期碱性玄武岩的Mg-Zn同位素研究

深部碳循环作为全球碳循环的重要组成部分，是目前地学领域的研究热点之一。研究表明碱性玄武岩可能与碳酸盐组分存在密切的成因联系，且通过Mg-Zn同位素研究揭示一些板内碱性玄武岩具有沉积碳酸盐的组分特征。可见，碱性玄武岩的Mg-Zn同位素组成不仅能够为示踪源区组分提供新的约束，且具有探索地球深部碳循环的潜力。然而大洋板内碱性玄武岩的Mg-Zn同位素研究非常薄弱。夏威夷-皇帝海山链复苏期通常由一套碱性玄武质岩石组成，是开展上述研究的理想对象。本项目拟以夏威夷Kauai岛复苏期碱性玄武岩为研究对象，基于已有全岩数据，重点开展原位矿物学和全岩Mg-Zn同位素研究，查明碱性玄武岩中与碳酸盐组分相关的矿物学信息，确定其地幔源区Mg-Zn同位素组成及端元组分（是否存在沉积碳酸盐组分）；厘清不同源区组分（特别是碳酸盐组分）在碱性玄武岩成因过程中所扮演的角色，揭示这些碱性玄武岩的成因机制及相关的深部碳循环过程。

As an important part of the global carbon cycle, Earth’s deep carbon cycle is currently one of the research hotspots in geoscience. Numerous studies have shown that there may be a close genetic relationship between alkaline basalts and carbonated components. The signature of recycled sedimentary carbonate was documented by Mg-Zn isotopic compositions in some intraplate alkaline basalts. These indicate that study of Mg-Zn isotopes in alkaline basalts not only could be used to trace the source components, but also could provide a potential for decoding the mechanism of Earth’s deep carbon cycle. However, such researches on oceanic intraplate alkaline basalts are still insufficient. The rejuvenated-stage alkaline lavas from the Hawaiian‐Emperor seamount chain could provide ideal subjects for the above studies. In this project, the rejuvenated-stage alkaline basalts from Kauai, Hawaii will be taken as the main object. Based on available data, we intend to conduct a systematic study on in situ mineralogy and whole-rock Mg-Zn isotopes. We prepare to identify the carbonate-related mineral assemblages retained in alkaline basalts, clarify the Mg-Zn isotopic compositions and end-member components (whether there are sedimentary carbonate components) in the mantle source, and determine the role of different source components (especially carbonate components) in the petrogenesis of alkaline basalts. Finally, these results will reveal the genetic mechanism of rejuvenated-stage alkaline basalts in Hawaii and related processes of deep carbon cycle.