用Hf-Fe-Mo同位素体系研究洋脊-地幔柱相互作用：以南太平洋Pukapuka海脊和东太平洋洋隆17-19°S为例

板块构造理论和地幔柱假说的提出是二十世纪固体地球科学领域的革命。它们解释了地球上板块边界和板块内部几乎所有的火山和地震活动。二者看似互不相关，实则相互补充。当地幔柱与大洋中脊（离散型板块边界）相遇，便会相互作用并产生一系列地质现象。过去几十年，人们主要通过研究洋脊-地幔柱相互作用的产物—玄武岩的元素、Sr-Nd-Pb同位素的时空变化来揭示其深部动力学过程。随着近些年越来越多非传统金属稳定同位素方法的开发，亟待结合这些新兴的金属稳定同位素方法和传统的元素、放射性成因同位素方法，对这些玄武岩开展系统研究。本项目拟以南太平洋Pukapuka海脊和东太平洋洋隆17-19°S的大洋玄武岩/玻璃为研究对象，主要研究其Hf-Fe-Mo同位素组成，并结合已发表的地球化学数据，进一步揭示这些玄武岩源区的地球化学特征以及其在时间和空间上的系统变化，为我们理解洋脊-地幔柱相互作用的起因、过程提供新的同位素制约。

Plate tectonics theory and mantle plume hypothesis have been great revolution in the field of solid-earth science in the last century. They explain almost all the volcanisms and earthquakes in both intra-plate and plate boundary settings. These two are genetically independent from each other, but mutually complementing. However, when the rising plumes approach the plate boundary, interactions between the two would inevitably produce a series geological result. To reveal the deep-mantle dynamic processes of the ridge-plume interactions, previous studies mainly focus on the produced basalt geochemical variations in temporal and spatial term. However, with the development of more and more kinds non-traditional metal stable isotopic methods in recent years, it is necessary and demanding to systematically study these basalts by incorporating all the traditional whole rock major element, trace element, radiogenic Sr-Nd-Pb-Hf isotopes methods and non-traditional stable isotopes methods. In this research, we will study oceanic basalts or fresh glasses from the Pukapuka Ridge in South Pacific Superswell and East Pacific Rise 17–19 °S. We will reveal the systematic temporal and spatial variations of the geochemistry in these basalts by comprehensive studying the radiogenic Hf isotopes and non-traditional stable Fe-Mo isotopes. This study will provide new isotopic constrains on our understanding of the cause and processes of the Ridge-Mantle plume interactions.