现代地质2024，Vol.38Issue(4)：1162-1176,15.DOI:10.19657/j.geoscience.1000-8527.2024.032
西南三江临沧地体澜沧岩群火山岩成因与构造意义
Genesis and Tectonic Significance of Volcanic Rocks from the Lancang Group in the Lincang Terrane,Sanjiang Region,Southwest China
摘要
Abstract
Studying the Lincang terrane is essential to understand the tectonic evolution of the Proto-Tethys in the Sanjiang region of Southwest China.However,there have been ongoing debates about its tectonic characte-ristics.This study focuses on the Lancang Group,which serves as the basement of the terrane.Our study presents zircon U-Pb chronology and whole-rock elemental composition of altered metavolcanic rocks in the area.The zircon U-Pb dating results indicate that these rocks formed during the Late Ordovician period,specifically at(457±2)Ma and(455±2)Ma.The protoliths of the 22 chlorite schists are from the low-potassium tholeiite series,while the protoliths of the six albite chlorite schists are basaltic-andesites from the high-potassium calc-alkaline-potassium basalt series.These rocks share similar characteristics with typical arc volcanic features,such as strong enrichment of light rare earth elements(LREEs),large-ion lithophile elements(LILEs),and negative anomalies of high field strength elements(HFSE).This evidence supports the idea that the Huimin magmatism was formed through the subduction of the Proto-Tethys Ocean to the Simao Block during the Ordovician-Silurian period.Therefore,we propose that the Lincang terrane may not be a distinct block with Precambrian basement,but rather a continental arc that formed through the subduction of the Proto-and Paleo-Tethys at the margin of the Simao Block.关键词
原特提斯/岩浆弧/临沧地体/澜沧岩群Key words
Proto-Tethys/magmatic arc/Lincang terrane/Lancang Group分类
地质学引用本文复制引用
张斌辉,王宏,牛浩斌,于远山,陈敏华..西南三江临沧地体澜沧岩群火山岩成因与构造意义[J].现代地质,2024,38(4):1162-1176,15.基金项目
中国地质调查局项目(DD20190053,DD20211386). （DD20190053,DD20211386）
