地球学报2025，Vol.46Issue(2)：283-297,15.DOI:10.3975/cagsb.2024.032101
内蒙古西乌旗巴布盖诺尔地区早二叠世花岗斑岩U-Pb年龄、地球化学特征及其地质意义
Zircon U-Pb Age and Geochemical Characteristics of the Granite Porphyry in the Babugainuoer Area,West Ujimqin Banner,Inner Mongolia and Their Geological Implications
摘要
Abstract
The Babuganuoer area,West Ujimqin Banner,Inner Mongolia,is located at the western 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.The 206Pb/238U ages of 12 spots of zircons from Sample SBLY-2 are between(269±3)-(279±3)Ma,with a weighted mean 206Pb/238U age of(274±3)Ma(MSWD=1.7).The 206Pb/238U ages of 12 spots of zircons from Sample SBLY-3 are between(269±3)-(282±4)Ma,with a weighted mean 206Pb/238U age of(275±3)Ma(MSWD=1.6).The above results reveal 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 formed in a post-collisional extensional setting and the Paleo-Asian Ocean was closed no later than the Late Permian.关键词
巴布盖诺尔/花岗斑岩/岩石地球化学/LA-ICP-MS/锆石U-Pb年龄/Hf同位素Key words
Babugainuoer/granite porphyry/petrogeochemistry/LA-ICP-MS/zircon U-Pb age/Hf isotopes分类
地质学引用本文复制引用
王承洋,陈伟,齐路晶,俞嘉嘉,孙珍军,黄静宜,杨乐,齐松..内蒙古西乌旗巴布盖诺尔地区早二叠世花岗斑岩U-Pb年龄、地球化学特征及其地质意义[J].地球学报,2025,46(2):283-297,15.基金项目
本文由防灾科技学院中央高校基本科研业务费专题项目(编号:ZY20215134)和国家自然科学基金青年科学基金项目(编号:42002093)联合资助. This study was supported by the Fundamental Research Funds for the Central Universities(No.ZY20215134),and National Natural Science Founda-tion of China(No.42002093). （编号:ZY20215134）
