洋壳物质再循环的Mo同位素示踪研究

运用非传统稳定同位素手段示踪重大地质过程是当前国际地球化学研究的前沿和热点。准确识别深部地幔中的再循环洋壳物质组分对理解地球内部物质和能量的循环过程具有重要意义。由于大洋板片俯冲脱水过程中Mo同位素的分馏导致残留板片和亏损地幔之间存在明显的同位素组成和Mo/Ce差异，因此Mo同位素体系有望成为洋壳物质再循环的新兴示踪剂。本项目拟对中国东部典型地区的新生代玄武岩（包括含有年轻的HIMU、EM1和EM2组分）开展详细的Mo同位素研究，并结合全岩主微量元素和Sr-Nd-Pb-Hf同位素地球化学研究，查明不同地幔端元组分玄武岩的Mo同位素组成特征和差异，揭示Mo在部分熔融、岩浆分异和地幔交代过程中的地球化学行为，探索Mo同位素体系示踪地幔中再循环组分的潜力，进而推动利用Mo同位素体系解决高温地质问题。

Tracing the major geological processes using non-traditional stable isotopes is the frontier issue and hotspot of international geochemical research. The identification of recycled oceanic crust components in the deep mantle is of vital importance to understand the circulation of material and energy in the Earth's interior. Mo isotopic fractionation during slab dehydration resulted in obvious differences in isotopic composition and Mo/Ce between residual slab and depleted mantle, thus the Mo isotopic system is expected to be a new tracer for oceanic crust materials recycling. This project intends to carry out detailed Mo isotopic study on the Cenozoic basalts from the eastern China (young HIMU, EM1 and EM2 components), combined with the whole-rock compositions and Sr-Nd-Pb-Hf isotopes, with the aims of obtaining the Mo isotopic composition of these basalts, revealing the geochemical behavior of Mo in partial melting, magma differentiation and mantle metasomatism, defining the fractionation mechanism of Mo isotope in deep mantle process, exploring the application potential of tracing the oceanic crust components recycling by using Mo isotopes, and promoting the Mo isotopes to solve the related scientific problems in the high temperature geological process.