华南地质2025，Vol.41Issue(3)：495-510,16.DOI:10.3969/j.issn.2097-0013.2025.03.003
粤北梅坑地区晚白垩世花岗岩成因及构造指示意义
Petrogenesis and Tectonic Implication of Late Cretaceous Granites in the Meikeng Area,Northern Guangdong Province
摘要
Abstract
In the Meikeng area of northern Guangdong,granite porphyry,fine-grained biotite granite and medium-grained porphyritic biotite granite are widely exposed.Those rock units constitute an important part of the Fogang batholith and provide key insights into the petrogenesis of granitoids in the central-north part of the pluton.This study presents an integrated investigation of petrology,geochemistry,zircon U-Pb chronology,and Hf isotope for these rocks,aiming to elucidate their origin and tectonic implicatons.The results indicate crystallization ages of 94.76±0.70 Ma,94.71±0.81 Ma and 95.51±0.78 Ma for granite porphyry,fine-grained biotite granite,and medium-grained porphyritic biotite granite,respectively,constraining their emplacement to the Late Cretaceous.These granites share similar geochemical features:high silica(SiO2=76.38-77.99 wt.%),metaluminous to weakly peraluminous copositions(A/CNK=0.98-1.09),and high alkali contents(K2O+Na2O=8.08-8.54 wt.%).They are enriched in Rb,Th,U,K,Nb,Nd,Zr and Hf,but depleted in Sr,P and Ti.The rocks exhibit light rare earth elements enrichment((La/Yb)N=5.605-16.134,ΣLREE/ΣHREE=5.91-11.51)and pronounced negative Eu anomalies(δEu=0.16-0.19).Zircon grains show εHf(t)values ranging from-7.6 to+6.7 and two-stage model ages(TDM2)between 0.60 and 1.35 Ga.The Meikeng granites are classified as highly fractionated I-type granites,derived primarily from partial melting of crustal materials,with possivle involvement of mantle-derived components during magmatic processes.In combination regional tectonic evolution,it is proposed that these Late Cretaceous granites formed in an intraplate extensional setting fellowing the retreat of the Paleo-Pacific plate.关键词
锆石U-Pb测年/Hf同位素/成因/佛冈岩体/梅坑/粤北地区Key words
zircon U-Pb dating/Hf isotopes/petrogenesis/Fogang batholith/the Meikeng area/Northern Guangdong Province分类
天文与地球科学引用本文复制引用
冯二明,刘晴,曾晓剑,曾裕源,庾佳,卢山松,高凤颖..粤北梅坑地区晚白垩世花岗岩成因及构造指示意义[J].华南地质,2025,41(3):495-510,16.基金项目
广东省自然资源厅"广东1∶5万蓝田圩、横石幅区域地质调查"项目(2023-20) （2023-20）
