哈尔里克山晚古生代混合岩地质特征、年代学及其构造意义

哈尔里克山位于天山造山带东北缘,是古亚洲洋板片俯冲、弧—陆(或弧—弧)增生拼贴造山作用的产物.出露于哈尔里克山南麓的中—高级变质带中发育有混合岩,其成因和时代尚无详细研究.文章对哈尔里克变质带中的混合岩进行了野外岩相—构造分析与LA-ICP-MS锆石U-Pb年代学研究.结果显示,该混合岩与高级变质沉积岩紧密伴生,可能是...

Geological Features and Geochronology of the Late Paleozoic Migmatites from the Harlik Range and Tectonic Significance

The Harlik Range is located in the northeastern part of the Tianshan Orogenic Belt and resulted from subduction of the Paleo-Asian Ocean and arc-continent or arc-arc accretionary orogeny.The Harlik metamorphic belt occurs at the southern foot of the Harlik Range and comprises high-grade metamorphic rocks and migmatites.Until now,the timing and genesis of migmatites are poorly studied.In this study,we conducted field structural investigations and LA-ICP-MS zircon U-Pb dating for the migmatites.The results show that the migmatites were likely derived from partial melting of high-grade meta-sedimentary rocks of the Harlik metamorphic belt.Numerous leucocratic dykes and in-source leucosome were deformed in various degrees and yielded consistent zircon U-Pb ages of 332-330 Ma.Considering the syn-kinematic characteristics of the in-source leucosome,it can be proposed that the migmatization and deformation of the Harlik metamorphic belt occurred in ca.330 Ma.Combining the previous studies on the metamorphic rocks and nearby plutonic rocks and taking the regional tectonic evolution into account,we suggest that the Harlik area probably underwent a post-orogenic setting since 330 Ma.The migmatites were likely formed by decompression partial melting and occurred as part of the basement of the Harlik arc,exhumation and uplifting of which might be related to the emplacement of the coeval post-collisional plutons.