地质力学学报2025，Vol.31Issue(3)：539-556,18.DOI:10.12090/j.issn.1006-6616.2024137
粤北澜河片麻状黑云母花岗岩的成因:锆石U-Pb年代学、Hf同位素和地球化学约束
Genesis of the gneissic biotite granite in Lanhe,northern Guangdong:Constraints from zircon U-Pb geochronology,Hf isotopes,and geochemistry
摘要
Abstract
[Objective]The Lanhe pluton in northern Guangdong is located at the southeastern margin of the Zhuguangshan Complex and is primarily composed of gneissic biotite granite;its petrogenesis has not yet been determined.[Methods]This study applied LA-ICP-MS zircon U-Pb geochronology,whole-rock geochemistry,and zircon Hf isotope analyses to the Lanhe gneissic biotite granite.[Results]U-Pb dating indicates that the emplacement age of the Lanhe gneissic biotite granite is 427±2 Ma,representing a product of the Caledonian magmatic activity.The geochemical characteristics show that the granite has SiO2 contents ranging from 71.53%to 75.41%,high total alkali contents(K2O+Na2O=7.57%-8.23%),and high A/CNK values(1.00-1.06).It is enriched in Rb,Th,U,and K,but depleted in Ba,Y,Nb,Ta,Sr,and Yb.The LREE/HREE ratios range from 9.49 to 28.15,with significant Eu negative anomalies(δEu=0.21-0.76).The zircon εHf(t)values of the samples are all negative(-11.8 to-5.2),with corresponding tDM2 values of 1806-2129 Ma.[Conclusion]Based on the geochemical and isotopic characteristics,the Lanhe gneissic biotite granite is identified as a highly fractionated I-type granite,primarily formed by partial melting of crustal metasedimentary rocks,including metagraywacke and metapelite.It is likely a product of the multi-stage reworking of the Paleoproterozoic basement during the Neoproterozoic to Early Paleozoic.The comprehensive study suggests that the Lanhe gneissic biotite granite formed in a syn-collisional tectonic setting during the Early Paleozoic in South China.[Significance]Integrated with the Zhuguang magmatic system and regional geological data,the Lanhe pluton likely represents a product of the transition from compressional thickening to post-collisional extension during the Caledonian Orogeny in South China.This transition may have been associated with intracontinental tectonic reorganization or external subduction-collision processes.关键词
澜河岩体/锆石U-Pb定年/地球化学/花岗岩/构造环境Key words
Lanhe pluton/zircon U-Pb Dating/geochemistry/granite/tectonic environment分类
地质学引用本文复制引用
王海洋,祁家明,钟福军,潘家永,夏菲,陈正乐,李文丽,刘军港,孙岳,严杰..粤北澜河片麻状黑云母花岗岩的成因:锆石U-Pb年代学、Hf同位素和地球化学约束[J].地质力学学报,2025,31(3):539-556,18.基金项目
国家自然科学基金项目(42362011,42272090) This research is financially supported by the National Natural Science Foundation of China(Grant Nos.42362011 and 42272090) （42362011,42272090）
