新疆北部后碰撞构造演化与成矿  

Post-collisional Tectonic Evolution and Metallogenesis in Northern Xinjiang,China

作　　者：王京彬[1] 徐新 

机构地区：[1]北京矿产地质研究院,100012 [2]新疆资源环境中心,乌鲁木齐830000

出　　处：《地质学报》2006年第1期23-31,共9页Acta Geologica Sinica

基　　金：国家重点基础研究发展规划"中国西部中亚型造山与成矿"项目(编号2001CB409806)资助成果

摘　　要：以夹于陆块间的蛇绿岩套构造就位及其伴随的区域变形变质、同碰撞花岗岩侵入时期,作为主碰撞期。后碰撞发生在主碰撞之后,并随大规模花岗质岩浆作用的结束而结束。依此标志,新疆北部后碰撞阶段的主体时限为早石炭世维宪期—晚二叠世。研究表明,新疆北部后碰撞阶段具有明显的继承性、旋回性、阶段性和方向性,经历了早石炭世伸展—晚石炭世挤压(隆升)和早二叠世伸展—晚二叠世挤压(隆升)两个伸展—挤压旋回。其中,早石炭世伸展可能与主碰撞导致的岩石圈板片拆沉有关,早二叠世伸展则可能与刚性增强的新陆壳下幔源岩浆的底侵作用有关。由多陆块碰撞过程中产生的巨大挤压应力,被后碰撞期不同机制幔源岩浆作用导致的阶段性伸展所消耗,由此逐步完成了碰撞后新陆壳的固结。新疆北部后碰撞的伸展阶段和挤压—伸展转变期,是大规模成矿的高峰期,并具有独特的成矿时空分布规律性。Post-collisional period follows the major collision, which is marked by the ocean closure and the ophiolite emplacement between/among the continental blocks, and ends with the exhaustion of large-scale granitic magma. According to these indicators, the major collision period of the northern Xinjiang is from the end of Devonian to the beginning of Carboniferous, while the post-collisional stage is from Early Carboniferous （Visean Stage） to Permian time. The data demonstrate that the post-collisional stage in northern Xinjiang experienced strong mantle-crust nmtual action and was characterized by episodic and oriented evolution. Two extensional-compressive episodes, the extension in Early Carboniferous and compression in Late Carboniferous, and the extension in Early Permian and compression in Late Permian, are recognized. It is suggested that the two extensional periods in the post-collisional stage may be caused by lithosphere delamination in Early Carboniferous after major impact and mantel magma underplating in Early Permian. Thus, the compression caused by collision was exhausted by episodic extensions, and gradually finished solidification of the crust during post-collisional stage. The extensional stage and the transition period from compression to extension are the most important periods for large-scale mineralization in the post-collisional regime.

关 键 词：后碰撞时限 构造演化 造山作用 成矿作用 新疆北部 

分 类 号：P542[天文地球—构造地质学] P611[天文地球—地质学]