| 内蒙古西乌旗巴布盖诺尔地区早二叠世花岗斑岩年代学、地球化学特征及其地质意义 |
| 投稿时间：2024-01-09 修订日期：2024-03-17 |
| 关键词:Babugainuoer granite porphyry petrogeochemistry zircon U-Pb age Hf isotopes |
| 基金项目:本文受国家自然科学基金青年科学(42002093)和防灾科技学院中央高校基本科研业务费专题项目(ZY20215134)联合资助。[通讯 |
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| Geochemistry, zircon U-Pb age and Hf isotope of the granite porphyry in the Babugainuoer area, West Ujimqin Banner, Inner Mongolia and their geological implications |
| The Babuganuoer area, West Ujimqin Banner, Inner Mongolia, is located at the westen slope of southern Great Xing’an Range. For the purpose of revealing its formation age, petrogenesis and tectonic significance, we conducted a comprehensive study of zircon U-Pb chronology, Hf isotope and whole-rock geochemistry for granite porphyry exposed in this area. Zircon U-Pb dating results indicate that these granitic rocks formed at 273 Ma~274 Ma, revealing that they were magmatic products of the Late Early Permian, rather than the previously believed Cretaceous. These rocks show characteristics of high silicon, low aluminum, low magnesium, high alkali, rich potassium and low sodium. These samples are enriched in Rb, Th, U, K elements and depleted in Nb, Ta, Ti elements, indicating a genesis of aluminous A-type granites. Zircons of these rocks have εHf(t) values of 8.2~11.1, and the two-stage Hf model ages (TDM2) of 588～789 Ma, suggesting that the Early Permian granitic rocks in the Babugainuoer area mainly derived from the newly accreted lower crust during the Neoproterozoic period. We comprehensively conclude that the Early Permian granitic rocks in the Babugainuoer area were s formed in a post-collisional extensional setting and the Paleo-Asian Ocean was closed no later than the late Permian. |
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