地质学报2026，Vol.100Issue(6)：2161-2180,20.DOI:10.19762/j.cnki.dizhixuebao.2025295
大兴安岭中段扎兰屯群浅变质岩的物源分析及构造意义
Provenance analysis and tectonic implications of low-grade metamorphic rocks of the Zhalantun Group in the central segment of Da Hinggan Mountains
摘要
Abstract
The Zhalantun island arc,situated in the central segment of Da Hinggan Mountains,hosts extensive exposures of Zhalantun Group low-grade metamorphic rocks and Early Palaeozoic arc-related magmatic suites,making it crucial for understanding the tectonic evolution of the Xing'an accretionary terrane.In this study,we conducted zircon U-Pb dating,whole-rock geochemistry,and Hf isotope analysis on muscovite quartz schist and fine-grained diorite from the Zhalantun-Arongqi area.Results indicate that protoliths of the muscovite quartz schist were sedimentary rocks(sandstone and greywacke)deposited during the late Early Paleozoic.The fine-grained diorite yielded a crystallization age of 521.8±2.4 Ma,confirming a genetic affinity with the Cambrian arc-volcanic belt of the Zhalantun island arc.Cambrian zircons from both the muscovite quartz schist and fine-grained diorite exhibit consistent Hf isotope signatures,characterized by variable positive and negative εHf(t)values indicative of a subduction-related magmatic source.Detrital zircon ages from the muscovite quartz schist can be categorized into four populations:① 475～427 Ma,derived from Early Paleozoic arc magmatic rocks within the Xing'an accretionary terrane;② 621～490 Ma(peak at～515 Ma),sourced from the Cambrian arc-volcanic belt;③ 996～756 Ma,primarily contributed by the Erguna block;and ④ 3313～1287 Ma,likely originating from both the Erguna and Songnen blocks.The low-grade metamorphic rocks of the Zhalantun Group exhibit unimodal detrital age distributions and proximal depositional characteristics consistent with a back-arc basin setting along an active continental margin,revealing the existence of an Early Paleozoic trench-arc-basin system in the Zhalantun island arc.关键词
大兴安岭/扎兰屯岛弧/扎兰屯群/物源分析/弧后盆地Key words
Da Hinggan Mountains/Zhalantun island arc/Zhalantun Group/provenance analysis/back-arc basin引用本文复制引用
徐建鑫,胡培远,翟庆国,王文东,郭宏宇,李超,李福明..大兴安岭中段扎兰屯群浅变质岩的物源分析及构造意义[J].地质学报,2026,100(6):2161-2180,20.基金项目
本文为中国地质调查局项目(编号DD202501026,DD20230250)、中国地质调查局东北地质科技创新中心区创基金项目(编号QCJJ2023-23)、国家自然科学基金项目(编号42072268)和中国地质科学院地质研究所基本科研业务经费(编号J2323)联合资助的成果. （编号DD202501026,DD20230250）
