Fe同位素在洋中脊高温地质过程中的分馏机制研究：以中大西洋洋脊33-35°N为例

固体地球科学40年来最主要进展之一是通过对大洋玄武岩Sr-Nd-Pb同位素的研究认识到地幔物质的不均一性。MC ICP-MS的诞生使Fe同位素分析精度大大提高，增加了人们对地幔物质Fe同位素不均一性的关注。但是，相对于Sr-Nd-Pb同位素，对大洋玄武岩Fe同位素的研究还比较薄弱，目前仍处于数据积累阶段，其在高温地质过程中的分馏机制不明确。本项目将使用MC ICP-MS系统分析研究中大西洋33-35°N 具有代表性的80个MORB样品的Fe同位素组成，从而（1）揭示中大西洋33-35°N MORB的Fe同位素不均一程度；（2）研究Fe同位素与其它地球化学指标（Fe3+/Fe2+、主-微量元素、Sr-Nd-Pb-Hf同位素）的相关性，探讨高温地质过程中Fe同位素的分馏机制。该研究结果将有助于丰富非传统稳定同位素的基础理论，同时也是大洋岩石圈成因与地幔动力学研究的重要进展。

One of the major advances in the solid earth science over the past 40 years is the recognition of mantle heterogeneity through Sr-Nd-Pb isotopic studies of oceanic basalts. The birth of Multi-collector Inductively Coupled Plasma Mass Spectrometer (MC ICP-MS) greatly improved the precision of the analyzed Fe isotope results, increasing the concern on Fe isotope heterogeneity of mantle materials. However, compared with Sr-Nd-Pb isotope systems, Fe isotope research of oceanic basalts is comparatively weak and still in the process of data accumulation, and the fractionation mechanism of Fe isotope in high-temperature processes remains enigmatic. In this case, this proposal focuses on systematic analyzing Fe isotopic compositions of 80 representative MORB samples from mid-Atlantic ridge 33-35°N using MC ICP-MS, to (1) reveal the Fe isotope heterogeneity of MORB from mid-Atlantic ridge 33-35°N; (2) study the potential correlations between Fe isotope and other geochemical parameters (Fe3+/Fe2+, Sr-Nd-Pb-Hf isotope, major-trace element), and discuss the Fe isotope fractionation mechanism in the mid-ocean ridge high-temperature geological processes. The research result will enrich the theory on the non-traditional stable isotopes, and is also the great improvement of research on the origin of ocean lithosphere and mantle geodynamics.