Petrogenesis and Tectonic Significance of Shenxianshui Alkaline Granite in Gejiu,Yunnan Province,China  

作　　者：YANG Rong CHEN Yongqing 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第2期368-385,共18页地质学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41972312 and 41672329);Kunming University of Science and Technology"Double First-class"Science and Technology Special Project(Grant No.202202AG050006).

摘　　要：The Shenxianshui granites in the western Gejiu area were formed in the Late Cretaceous.Laser ablation inductively coupled plasma mass spectrometry indicates zircon U-Pb ages ranging from 90.67±0.7 to 85.97±0.6 Ma.The intrusive rocks are peraluminous(A/CNK=1.03 to 1.33)and calc-alkaline,showing an affinity towards I-type granite.Large ion lithophilic elements are enriched in K and Rb,while high field strength elements are depleted.Moreover,light rare earth elements are significantly enriched,showing a slight negative Eu anomaly(Eu/Eu^(*)=0.39 to 0.58).Shenxianshui granite has a relatively high initial Sr isotope ratio(^(87)Sr/^(86)Sr)_(i)(0.7098-0.7105),negative ε_(Nd)(t)values(−7.99 to−7.44)and negative ε_(Hf)(t)values(−8.37 to−2.58).Combined with previous studies,these characteristics suggest that the Shenxianshui alkaline granites were formed in a post-collision extensional environment.The alkaline granitic magma possibly originated from the partial melting of the lower crust during the Mesoproterozoic era and may have contained mantle source materials.Shenxianshui alkaline granite was formed from mixed magma with a high degree of crystal differentiation.The abundance of ore-forming elements indicates that Shenxianshui granite has the potential to mineralize key metals and rare earth elements.

关 键 词：I-type granite zircon U-Pb geochronology Sr-Nd-Pb isotopes Hf isotope Gejiu 

分 类 号：P588.121[天文地球—岩石学]