东疆星星峡地区淡色花岗岩的成因及其蕴含的古老地壳组成信息

中天山地块作为中亚造山带南部的主要微陆块之一，在限定造山带的整体构造格架上具有重要作用。然而，目前对这些古老微陆块在增生造山作用中的基底变质、地壳深熔及地壳分异等过程尚不清楚。中天山地块中断续分布的淡色花岗岩与前寒武纪基底岩石在空间上密切相关，蕴含了丰富的地壳组成和演化信息，是深入研究上述问题的理想对象。本项目拟对在中天山地块星星峡地区新发现的几处淡色花岗岩进行详细的野外地质、岩石学、年代学和地球化学研究，并结合已有资料的分析和对比，揭示本区淡色花岗岩的时空分布规律，阐明不同期次淡色花岗岩的源区物质组成和地壳深熔作用的类型与机制，分析其与基底岩石的变质作用和混合岩化之间的成因联系，揭示其蕴含的中天山地块古老地壳时代和组成的重要信息，为中天山地块前寒武纪地壳基底的形成与演化以及中亚造山带的构造演化研究提供新的有力证据。

The Central Tianshan Block (CTB), as one of the major microcontinents of the southern Central Asian Orogenic Belt (CAOB), would carry important significances in the definition of the basically tectonic architecture of the CAOB. At present, relatively little is known about the metamorphism, anatexis and differentiation processes of the crustal basements in the microcontinents of the CAOB in response to the accretionary orogeny. The leucogranites scattered in the CTB provide a unique opportunity to understand these processes since they show a close spatial relationship with the Precambrian basements of the CTB and contain abundant information concerning the crustal composition and evolution. In this proposal, we plan to conduct detailed field geological, petrographic, geochronological, and petrogeochemical studies for several leucogranite bodies which were discovered from the Xingxingxia area of the CTB. Combined with the analysis and comparison of previously published data, these new data will be used to reveal the temporal and spatial distribution rule of the leucogranites in the Xingxingxia area, elucidate the magma sources and anatectic types and mechanisms for the different stages of leucogranites, probe the genetic link between the leucogranites and metamorphism and migmatization of the basement rocks of the CTB, and to figure out the information about the age and composition of the ancient crust in the CTB. The results will provide significant insights into the Precambrian crustal formation and evolution of the CTB as well as the understanding of the tectonic evolution of the CAOB.