岩石矿物学杂志2026，Vol.45Issue(3)：427-446,20.DOI:10.20086/j.cnki.yskw.2026.5111
内蒙古中部乌兰陶勒盖地区晚二叠世二长花岗岩的成因及其构造意义
Petrogenesis and tectonic implications of the Late Permian monzogranite in the Wulantaolegai Area,central Inner Mongolia
摘要
Abstract
The Central Asian Orogenic Belt(CAOB)is the largest Phanerozoic accretionary orogenic belt on Earth,and central Inner Mongolia is widely regarded as the key segment marking the final closure of the Paleo-Asian Ocean within the CAOB.As a critical region for constraining the tectonic transition that followed the closure of the Paleo-Asian Ocean,central Inner Mongolia has long attracted considerable attention owing to its complex tectono-magmatic evolution.In this study,the monzogranite exposed in the Wulantaolegai area was investigated through petrography,whole-rock major-and trace-element geochemistry,LA-ICP-MS zircon U-Pb geochronology,and zir-con Hf isotopic analyses to constrain its emplacement age,magma source,and tectonic setting.The results show that the monzogranite yields a zircon U-Pb age of 259.2±3.8 Ma(MSWD=1.2),indicating emplacement in the Late Permian.Whole-rock geochemical data indicate that the pluton is characterized by high silica(SiO2=73.43％～75.15％),elevated Al2O3(13.32％～14.24％),high total alkalis(Na2O+K2O=8.18％～8.61％),and low Fe-Mg contents,with aluminum saturation indices(A/CNK)of 1.05～1.11.It is enriched in light rare earth ele-ments and large-ion lithophile elements such as Rb,Th,and K,but depleted in heavy rare earth elements and in Nb,Sr,P,and Ti,and is dominated by negative Eu anomalies,thus belonging to weakly peraluminous Ⅰ-type granite.Zircon Hf isotopic compositions yield εH f(t)values of-16.44 to-2.04 and two-stage Hf model ages(tDM2)of 2 322～1 413 Ma,suggesting that the magma was derived predominantly from partial melting of ancient crustal materials,with the possible involvement of a very minor depleted component.In combination with the re-gional tectono-magmatic evolutionary framework,we propose that the Late Permian monzogranite in the Wulantaole-gai area was generated by crustal remelting under a post-closure lithospheric thinning or extensional regime following the closure of the Paleo-Asian Ocean,indicating that central Inner Mongolia had entered a post-collisional to post-orogenic extensional tectonic regime by the Late Permian.关键词
二长花岗岩/锆石U-Pb年龄/岩石成因/构造意义/乌兰陶勒盖/古亚洲洋Key words
monzogranite/zircon U-Pb age/petrogenesis/tectonic significance/Wulantaolegai/Paleo-Asian Ocean分类
天文与地球科学引用本文复制引用
高栋,焦建刚,陈圣,陈泳帆,伍明媚,刘龙龙,王佳新,吴才来..内蒙古中部乌兰陶勒盖地区晚二叠世二长花岗岩的成因及其构造意义[J].岩石矿物学杂志,2026,45(3):427-446,20.基金项目
长安大学中央高校基本科研业务费专项资金(300102273502) （300102273502）
岭南师范学院高层次人才引进项目(000302302635) （000302302635）
国家自然科学基金项目(41872071,42102161) Fundamental Research Funds for the Central Universities,Chang'an University(300102273502) （41872071,42102161）
The High-level Talent Introduction Project of Lingnan Normal University(000302302635) （000302302635）
National Natural Science Foundation of China(41872071,42102161) （41872071,42102161）
