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为探讨兴蒙造山带南蒙古陆块南缘晚古生代的构造演化,对出露于西乌旗南部石英闪长岩、花岗闪长岩和黑云母花岗岩开展了详细的年代学、岩石地球化学及Hf同位素特征研究.结果表明:石英闪长岩、花岗闪长岩和黑云母花岗岩分别形成于330±2Ma、274±1Ma及271±1Ma~282±1Ma.石英闪长岩属高镁闪长岩/安山岩类(HMA),与俯冲洋壳板片上部地幔楔中地幔橄榄岩的熔融作用有关,而花岗闪长岩及黑云母花岗岩的源区可能与新生地壳的部分熔融有关.结合区域成果,推测西乌旗南部晚古生代侵入岩均形成于古亚洲洋向北侧南蒙古陆块持续俯冲的阶段,早石炭世石英闪长岩属活动大陆边缘弧岩浆活动,早二叠世花岗闪长岩和黑云母花岗岩则是俯冲过程中短暂弧后伸展阶段的产物.
In order to investigate the tectonic evolution of the Late Paleozoic in the southern margin of the southern Mongolia block of the Xingmeng orogenic belt, detailed geochronology and petrogeochemistry of quartz diorite, granodiorite and biotite granite exposed in the southern part of Xiyuqi were carried out. And Hf isotopic characteristics of quartz diorite.The results show that quartz diorite, granodiorite and biotite granite are formed at 330 ± 2Ma, 274 ± 1Ma and 271 ± 1Ma ~ 282 ± 1Ma, respectively. The feldspar / andesite (HMA) is related to the melting of the mantle peridotite in the upper mantle wedge of the subducting oceanic crust, while the source regions of granodiorite and biotite granites may be related to the partial melting of the nascent crust. According to regional results, it is speculated that Late Paleozoic intrusions in the southern part of Xikwu Qi were formed during the continuous subduction of the southern Mongolia block to the north of the Paleo-Asian Ocean. The Early Carboniferous quartz diorite is an active continental margin arc magmatic activity. The Early Permian The diorite and biotite granite are the products of a short post-arc extension in the subduction process.