花岗岩成因的磷灰石微区地球化学和Sr-Nd同位素制约

花岗岩类岩石是大陆地壳的重要组成部分，其成因和演化过程与大陆地壳的形成和分异密切相关。花岗岩的形成经历复杂源区和演化过程，如何有效识别岩浆源区和示踪精细成岩过程是花岗岩成因研究的核心内容。磷灰石是花岗岩中常见的副矿物，矿物中富含REE、Sr、S及挥发份（F、Cl）等地球化学指标元素，可以为岩浆演化提供年代学、元素和Sr-Nd同位素、挥发份及岩浆氧逸度等信息，从而建立岩浆体系的物质成分等随时间的演化过程，对示踪花岗岩成因具有独特的优势。磷灰石不仅出现在岩浆结晶早期，且随着岩浆演化不断饱和析出，可以记录更长的岩浆演化历史。本项目拟选取辽东半岛具有典型成因的早白垩世花岗岩为研究对象，通过对磷灰石微区元素和Sr-Nd同位素等分析，揭示不同成因的花岗岩中，磷灰石成分环带的特征和成因。从磷灰石的角度，建立示踪不同类型岩浆过程的地球化学指标，完善花岗岩成因的地球化学示踪方法。

Granitoids and related rocks are the main components of the continental crust, and their genesis and evolution process are closely related to the formation and differentiation of the continental crust. Granitoids have been proved to be formed by complex magma sources and multi-stage magmatic processes, which make the effective discrimination of magma sources and processes become the focused study of granite genesis. Apatite is commonly occurred in granitoids, which is rich in REE, Sr, S, volatiles (F, Cl) and other geochemical index elements. It can provide the information of geochronology, elemental and Sr-Nd isotopic compositions, volatiles contents and magmatic oxygen fugacity, which are useful to establish the magmatic evolution over time. Thus, the study of apatite has unique advantages as a genetic tracer of granitoids. Apatite not only appeared in the early stage of magma crystallization, but also continuously saturated during magma evolution, thus record a long evolution history of the host magma. Three typical early Cretaceous granitic plutons, which were formed by complex magma source and multi-stage processes according to the previous study, are concerned in this study. Based on the in-situ elemental and Sr-Nd isotopic studies, the characteristics and genesis of apatite zonation formed in granite with different genesis will be revealed. From the perspective of apatite, the geochemical indexes for tracing different types of magmatic processes can be established to supplement the tracing method for the petrogenesis of granitoids.