北祁连早古生代大陆弧的架构：对大陆地壳生长和再造过程的制约

A suite of early Paleozoic continental arc rocks have been recognized in the Menyuan-Kekeli area of the North Qilian Mountains; primary data indicate that these arc rocks are similar to continental crustal profile of typical magmatic arc, which is an idea site for studying growth and differentiation of continental crust. The proposed research will focus on the arc rocks in the Menyuan-Kekeli area of the North Qilian Mountains. Based on detailed field survey and large-scale mapping, together with studies on metamorphism, anatexis and magmatism, and in combination with geochemical and multi-geochronological methods, the aims of this proposal are 1) to confirm the rock assemblies, architecture and the field relationship of the continental arc; 2) to unravel the metamorphic and deformational sequences, process and reprinting relationship, and thus reconstruct the PTD evolution of different type rocks in the continental arc; 3) to explore the features of anatexis in the arc root，and formation environment, source nature of magma and original geodynamic settings. Finally, we also will try to provide some new idea for growth and reworking of continenetal crust.

北祁连门源-柯柯里地区发育一套早古生代大陆边缘弧岩石组合，初步的研究资料显示它们与典型的大陆弧地壳剖面的组成特征基本一致，是探究大陆地壳生长和分异过程的理想场所。本项目申请拟选择门源-柯柯里地区的早古生代大陆弧岩石为研究对象，以详细的野外构造剖面的穿切及大比例填图为基础，以变质、变形和岩浆作用为主线，结合地球化学及多种同位素年代学方法，1）确定大陆弧地壳剖面的岩石组成、空间分布特征及野外关系；2）解析不同类型岩石的变质变形期次、过程及相互叠加关系，从而恢复其各自的峰期变质条件及PTD演化历史; 3）揭示大陆弧根的深熔机制以及弧岩浆岩的形成环境、源区性质和深部动力学机制。在此基础上，综合相关领域资料，力争在在大陆地壳生长和再造过程等研究方面有所创新。

北祁连南缘发育一套早古生代大陆边缘弧岩石组合，它们与典型的大陆弧地壳剖面的组成特征基本一致，为探究大陆地壳生长和分异过程提供了理想场所。本项目紧扣北祁连早古生代大陆弧的架构这一中心，聚焦三方面的科学目标： 1）确定大陆弧地壳剖面的岩石组成、空间分布特征及野外关系；2）解析不同类型岩石的变质变形期次、过程及相互叠加关系，从而恢复其各自的峰期变质条件及PTD演化历史; 3）揭示大陆弧根的深熔机制以及弧岩浆岩的形成环境、源区性质和深部动力学机制。基于本项目的研究，我们首次在青藏高原北缘祁连造山带构建完整的“安第斯型”大陆弧地壳的物质组成及结构剖面，理清了俯冲-增生造山过程中变质-深熔响应与大陆地壳活化和再造的关系—确定了弧岩浆就位引发的地壳加厚和地温梯度上升，是同期高温变质-深熔作用等地壳活化过程的主要诱发机制；提出祁连造山带长周期俯冲-增生和碰撞造山模型，完整地约束了新元古代-古生代原特提斯域祁连造山系的构造演化历史。相关成果已在Earth-Science Reviews, Tectonics, Geological Society of America Bulletin 等地学主流刊物发表SCI论文25篇，培养博士研究生2名。