哈萨克斯坦Kokchetav地区新元古代晚期-早奥陶世火山岩年代学、成因及其构造意义

哈萨克斯坦Kokchetav地块是中亚造山带西段最大的前寒武纪地质体之一，该地块及周边地质体在新元古代晚期-早古生代俯冲增生过程是区域内重要的构造事件。地块边缘Daut、Imanburluk、Stepnyak地区火山岩形成时代与岩石成因的多解性制约了对相关演化过程的理解。本项目拟以上述区域火山岩为研究对象，在详细的野外地质调查基础上，通过锆石LA-ICP-MS U-Pb定年、锆石Lu-Hf及全岩Sr-Nd同位素示踪、全岩与单矿物化学成分分析等技术手段，精确厘定岩石形成时代, 建立新元古代晚期-早奥陶世俯冲作用中火山岩时空序列;揭示岩浆形成温压条件、源区特征与演化过程。结合前人研究成果，探讨Kokchetav地块边缘区域在新元古代晚期-早古生代洋陆构造格局中块体构造属性，恢复俯冲增生构造过程。本研究旨在为理解中亚造山带西段新元古代-早古生代构造演化史提供重要约束。

The subduction-accretion process of Kokchetav micro-continent with Precambrian basement and its surrounding area, located in northern Kazakhstan, during , late Neoproterozoic to Early Palaeozoic is one of the most important events in terms of regional tectonic evolution. The formation age and petrogenesis of the volcanic rocks exposed in Daut, Imanburluk, Stepnyak areas are ambiguous, which has strictly hindered our understanding of the tectonic settings during this time span. On the basis of detailed geological survey and sampling, the accurate formation age and space-times series of different volcanic rock types, source characteristics, temperature and pressure conditions, evolution of parent magma of volcanic rocks will be investigated through multi-methods of zircon U-Pb dating, major and-trace elements geochemistry, zircon Lu-Hf andwhole-rock Sr-Nd isotopic analysis. Accordingly, the tectonic scenario of the Kokchetav microcontinent and its surrounding area during Late Neoproterozoic to Early Ordovician will be discussed. The research results will provide significant information and scientific basis for limiting the subduction-accretion processes of the western Central Asian Orogenic Belt.