地幔是地球最大的Ti储库，了解其Ti同位素组成以及在地幔深部过程中Ti同位素的分馏机制是正确运用Ti同位素示踪的前提。然而，目前尚缺乏地幔橄榄岩样品的Ti同位素组成研究，Ti同位素在地幔深部过程（如部分熔融和地幔交代）中的行为还不清楚，限制了其在高温地质过程中的应用。本项目拟以西伯利亚、蒙古和我国华北典型地区不同类型地幔橄榄岩为研究对象，通过研究未受地幔交代的饱满的橄榄岩及其组成矿物的Ti同位素组成，更合理的限定硅酸盐地球的Ti同位素组成，并建立平衡状态下Ti同位素在地幔各矿物间分馏次序；通过研究经历了不同程度地幔部分熔融或地幔交代的橄榄岩及其组成矿物的Ti同位素组成，结合已有的岩石学和地球化学资料，查明部分熔融和地幔交代过程中Ti同位素的分馏尺度及机制。本项目的开展，有望填补相关研究的空白，实现Ti同位素理论框架研究上的突破，从而推动利用Ti同位素来解决地球科学相关问题。

The mantle is the Earth’s largest reservoir for Ti. Knowledge of Ti isotopic composition of mantle and the behavior of Ti isotopes in mantle processes is the prerequisite for using Ti isotope as a potential tracer to characterize mantle processes. However, the Ti isotopic study of mantle peridotites has not previously been done and the behavior of Ti isotopes in mantle processes such as partial melting and mantle metasomatism is still unclear, which limits its application in high temperature geological processes. The principal objective of this project is to provide better constrain the Ti isotopic composition of the mantle and to investigate potential Ti isotopic fractionation during partial melting and metasomatism, based on analyses of appropriate mantle peridotites as well as their constituent minerals from Siberia, Mongolia and the north China Craton. The Ti isotopic compositions of fresh, unmetasomatised fertile peridotites as well as their constituent minerals will be used to further constraint on the Ti isotopic composition of the Bulk Silicate Earth and the magnitude of equilibrium inter-mineral Ti isotopic fractionation at high temperatures. The Ti isotopic compositions of mantle peridotites which experienced various degrees of partial melting or different metasomatic histories, together with previous petrologic and geochemical evidence will be used to reveal the magnitude and mechanism of Ti isotopic fractionation during partial melting and mantle metasomatism. We hope this project will provide reliable data which will be helpful to promote the applications of Ti isotopes in high temperature processes, and in the whole earth science system gradually.