地壳深熔岩石中转熔矿物研究及其对混合岩和S型花岗岩成因的制约

转熔矿物是岩石发生不一致部分熔融的产物，携带了地壳深熔过程中源区物质和熔体的大量信息，与高级变质岩和花岗岩中残留矿物和岩浆中结晶矿物具有不同的来源。准确识别这些不同成因的矿物相，是研究高温变质作用的基础，对研究混合岩和S型花岗岩的成因都起着非常重要的作用。由于目前对高温变质岩石中转熔矿物及其形成条件的研究比较有限，本项目拟以青藏高原拉萨地体混合岩和S型花岗岩为研究对象，通过系统的岩相学、矿物微区元素和同位素以及热力学相平衡研究，准确识别出混合岩和S-型花岗岩中的转熔矿物，建立识别转熔矿物的岩石地球化学指标。在此基础上，进一步确定拉萨地体中混合岩的形成机制和变质P-T-t演化历史，探讨S型花岗岩成分变化的成因机制，揭示该区地壳深熔与青藏高原构造演化的关系。

Peritectic mineral is the product of incongruent melting reaction. It provides important information on the source materials and melt compositions for crustal anataxis, and has much different origins from metamorphic relics and magmatic minerals crystallized from melts. Distinguishing these minerals is fundamental to high-temperature metamorphism, and very important for the origins of migmatites and S-type granites. As there is limited study on peritectic minerals and its formation conditions, this project focuses on the migmatites and S-type granites from the Lhasa terrane in southern Tibet. Careful petrographic observation with special attentions to identification of mineral and melt inclusions, mineral major and trace elements, radiogenic and stable isotopes in minerals, as well as phase equilibration calculations will be systematically investigated. The results will be used to distinguish peritectic minerals from metamorphic relics and magmatic minerals in migmatites and granites, establish the petrological and geochemical criteria for the identification of peritectic minerals. In addition, this project will explore the formation mechanism of migmatites and their P-T-t paths, the origin of the compositional variations in S-type granites， and the relationship between crustal anatexis of Lhasa terrane and the evolution of Tibetan Plateau.