青藏高原幔源超钾质岩浆作用的研究对于揭示岩石圈地幔物质组成、探索地球深部碳循环过程、反演与高原隆升相关的深部动力学过程具有重要意义。本项目在前期研究的基础上，聚焦于青藏高原南部麦嘎地区具有高镁、低硅特征的碰撞后超钾质岩浆记录。通过锆石U-Pb定年和原位Hf-O同位素分析，完善拉萨地块碰撞后岩浆活动的时空格架，约束地壳混染作用对超钾质岩石地球化学组成的影响。把镜下观察和矿物的原位微区分析结合起来，阐明超钾质岩浆的演化过程，估算岩浆形成的温度和压力，恢复原始岩浆的组成。在此基础上，应用Sr-Nd-Ca-Mg同位素详细刻画新特提斯洋壳和印度大陆地壳物质在俯冲过程中对藏南岩石圈地幔的交代改造过程。本项目成果可以为构筑中新世高原深部动力学过程提供新的岩石学和地球化学依据。

The mantle-derived ultrapotassic magmatism in Tibetan plateau provides a prime opportunity to probe into the nature of mantle lithosphere, to investigate the deep carbon recycling processes, and to reveal the geodynamic mechanism responsible for plateau uplift. This project, which is based on our previous research, will present a systematic study on the high-MgO and low-SiO2 ultrapotassic rocks from Maiga area, southern Tibet. Zircon U-Pb dating and in situ Hf-O isotopic analyses will improve our understanding of the temporal and spatial distributions of postcollisional magmatism in Lhasa terrane, and provide reliable constraints on the influence of crustal contamination on the evolution of ultrapotassic magma. A combination of petrography and mineral in situ analysis will allow us to elucidate the magmatic evolution, to calculate the pressure and temperature of magmatic generation, and to estimate the properties of primary ultrapotassic magma. With the aid of Sr-Nd-Ca-Mg isotopic analyses, we will be able to clarify the mantle metasomatism occurred beneath south Tibet during the obliteration of Neo-Tethyan ocean and subsequent subduction of Indian continental lithosphere. In summary, this project will be able to provide new petrological and geochemical constraints on the geodynamic processes occurred beneath Tibetan plateau in the Miocene.