摘要
江西庐山地区星子群片麻岩的构造属性对认识江西甚至华南的大地构造具有重要意义。对星子群片麻岩穹窿不同构造部位的4个片麻岩中独居石进行高精度SIMS U-Pb年龄测定,结果显示它们的206Pb/238U加权平均年龄分别为141.0±1.0 Ma、143.0±1.0 Ma、143.5±1.0 Ma和144.2±1.6 Ma,因此将星子群的峰期变质时代限定于141.0~144.2 Ma。同时本文首次报道了庐山观音尖辉长岩的锆石SIMS U-Pb定年,确定其侵位年龄为141.1±1.5 Ma,这与星子群片麻岩独居石获得的峰期变质年龄在误差范围内一致。结合星子群的变质温度和变质分带特征,推测庐山片麻岩穹窿可能是中生代岩浆热穹窿,其角闪岩相的变质作用可能是岩浆热动力变质的产物。本研究不仅为庐山地区构造变形属性的厘定提供了详实的定年证据,还能为中国东部中生代板内强烈变质变形的研究提供重要参考。
The metamorphism mechanism and tectonic affinity of the Lushan gneiss dome are still controversial,mainly because of insufficient constraints on peak metamorphism timing of the Xingzi Group gneiss in the core of the Lushan dome.Here we present high resolution SIMS monazite U-Pb isotopic dating results of four gneiss samples from different tectonic positions.SIMS U-Pb dating on metamorphic monazite from the Xingzi gneiss yielded weighted-mean 206Pb/238U age of 141.0±1.0 Ma,143.0±1.0 Ma,143.5±1.0 Ma,144.2±1.6 Ma,respectively.Thus,the range of 141.0–144.2 Ma is interpreted as the peak metamorphic timing of the Xingzi Group gneiss.Also we report the first SIMS zircon U-Pb age of 141.1±1.5 Ma for the Guanyinjian gabbro in the Lushan area.It is interpreted as the emplacement age of the Guanyinjian gabbro pluton,which is consistent with the peak metamorphism timing of the Xingzi Group.Combined with the previously published geochronological data of pegmatite dike,migmatite,and structural features of the gneiss from the Xingzi Group,we inferred that the Xingzi Group gneiss could be the product of dynamo-thermal metamorphism by the concealed Mesozoic pluton.This study not only provides detailed geochronological data for the magmatism-metamorphism and deformation of the Lushan area,but also provides valuable information for the study of the intensive intraplate metamorphism in Eastern China.
作者
侯莹玲
莫佳君
何斌
徐义刚
王继林
HOU Yingling;MO Jiajun;HE Bin;XU Yigang;WANG Jilin(College of Petroleum Engineering,Guangdong University of Petrochemical Technology,Maoming 525000,Guangdong,China;State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;Shandong Bureau Testing Center of China Metallurgical Geology Bureau,Jinan 250014,Shandong,China)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2023年第2期249-259,共11页
Geotectonica et Metallogenia
基金
广东省普通高校青年创新人才类项目(2018KQNCX161)
广东石油化工学院科研启动基金项目(2018rc10)联合资助。
