地质论评2025，Vol.71Issue(4)：1197-1214,18.DOI:10.16509/j.georeview.2024.12.075
辽东桓仁地区中生代花岗岩锆石U-Pb年龄、Hf同位素特征及其地质意义
Zircon U-Pb ages,Hf isotope composition,and geochemical characteristics of Mesozoic granite in Huanren area,Eastern Liaoning
摘要
Abstract
This paper conducted petrological,geochemical,zircon U-Pb chronology and Hf isotope studies on the Guchengzi monzogranite and the Yezhugou alkali-feldspar granite in the Huanren area of eastern Liaoning.The petrological and geochemical characteristics show that the Guchengzi monzogranite and the Yezhugou alkali-feldspar granite are respectively metaluminous-weakly peraluminous highly differentiated I-type granite and metaluminous-weakly peraluminous A-type granite.The zircon U-Pb dating results of LA-ICP-MS show that the age of I-type granite is 125.0±0.6 Ma and that of A-type granite is 116.3±0.9 Ma,both are the products of Early Cretaceous magmatism.Both granites are enriched in Rb,Th,U,K,and light rare earths,and depleted in Ba,Sr,P,and Ti.However,compared with the alkali-feldspar granite,the monzogranite has lower Rb/Sr and Rb/Ba ratios and a higher K/Rb ratio,and exhibits a more significant negative Eu anomaly,indicating that the two types of granites have different degrees of differentiation and evolution.The zircon Hf isotope compositions of the two types of granites have a relatively large range of variation,with the εHf(t)variation range of-22.20 to-16.02 for diorite granite and-15.98 to-11.42 for alkali feldspar granite.The variation range of ε Hf(t)value is large,indicating that multiple components should be involved in the diagenetic process.The significant differences of diagenetic time and compositions indicate that the two kinds of granites could not have originated from the same primitive magma.The formation of both types of granites has undergone a two-stage diagenetic process in which mantle-derived magma mixed with felsic magma produced by melting crustal material in the deep crust,and followed by different extents of crystallization differentiation.Combined with regional tectonic evolution,the formation of the two types of granites may be related to the extensional tectonic setting of the lithospheric caused by the subduction of the Pacific Plate towards the Eurasian Plate and the extension of the trailing edge in the late Early Cretaceous.关键词
锆石U-Pb测年/Hf同位素/I型花岗岩/A型花岗岩/伸展构造环境/辽东Key words
zircon U-Pb dating/zircon Hf isotope/I-type granites/A-type granites/extensional tectonic/environment/Eastern Liaoning引用本文复制引用
余超,杨玉伟,田毅,苏特,王广伟,杨新宇,鲍东明,张天元..辽东桓仁地区中生代花岗岩锆石U-Pb年龄、Hf同位素特征及其地质意义[J].地质论评,2025,71(4):1197-1214,18.基金项目
本文为中国地质调查局地质调查项目"辽宁1/5万响水河子等两幅区域地质调查(编号:DD20160049-9)"的成果. This study is supported by Geological Survey Project of China(No.DD20160049-9). （编号:DD20160049-9）
