俯冲带俯冲输入与弧/弧后输出的关系是当前海洋地质学研究的热点，琉球俯冲带由于其完整的“沟-弧-盆”构造格局及特殊地理位置，成为研究俯冲输入与弧/弧后输出关系的理想对象。本项目选取西菲律宾海盆代表性沉积物样品与冲绳海槽玄武岩样品，开展岩石地球化学与同位素组成分析，通过K、Ba、Sr、Th、Nb等特征微量元素示踪研究，以证实俯冲的沉积物可以循环进入弧后盆地，对弧后盆地岩浆化学组成产生一定影响；并通过Sr-Nd同位素二元混合模拟计算，定量研究俯冲沉积物对弧后盆地岩浆活动的贡献程度。从俯冲沉积物的角度思考弧后盆地岩浆化学组成变化的原因，并利用沉积物和弧后盆地玄武岩微量元素进行示踪研究，以阐明俯冲沉积物的物质循环方式和对弧后盆地岩浆活动的影响，这是本项目在研究思维上的特色与创新之处。本研究有助于深化理解俯冲带俯冲输入与弧及弧后输出的关系，对俯冲沉积物的物质和能量循环的研究具有重要科学意义。

The relationship between subduction input and arc /back-arc output at subduction zone is a hotspot for marine geologists all over the world. Ryukyu subduction zone, due to its complete "trench - arc - basin" tectonic framework and special location, has seen as the best object for studying the relationship between subduction input and arc /back-arc output. In this project, we select representative samples of west Philippines sea basin and Okinawa Trough, carry out geochemical and isotopic composition analysis. By tracing K, Ba, Sr, Th, Nb and other trace elements, to confirm that subducted sediments can be recycled into the back-arc basin, and change the chemical composition of magma of back-arc basin. And by using binary mixed simulation of Sr-Nd isotope, to make quantitative research of sediments contributed to back-arc magmatism. The innovation of this project is the idea to take the influence of subducted sediments into account. By tracing trace elements between sediment and back-arc basalt, to clarify the way subducted sediment material cycle and back-arc basin magmatism impact. This study will help to deepen the understanding of the relationship between subduction input and arc and /or back-arc output at subduction zone. Moreover, this study has important scientific significance for researches of the subducted sediment material and energy cycle.