现代地质2018，Vol.32Issue(2)：316-328,13.DOI:10.19657/j.geoscience.1000-8527.2018.02.10
西秦岭西段共和盆地周缘西功卡花岗闪长岩体锆石U-Pb年龄、地球化学特征及其构造意义
Zircon U-Pb Ages, Geochemical Characteristics and Tectonic Implications of Xigongka Granodiorite Around Gonghe Basin,West of Western Qinling Mountains
摘要
Abstract
Xigongka granodiorite is located in Gonghe Basin,west of the Western Qinling mountains Orogenic Belt,and the main composition of rock is gray,fine-grained,block granodiorite.In this paper,we carried out the petrography,zircon U-Pb geochronology and geochemistry of Xigongka granodiorite.Zircon LA-ICP-MS U-Pb dating yielded a weighted mean age of (227.2 ± 7.3) Ma,which is interpreted as the emplacement age of the Xikongka intrusion.The Xigongka intrusion is weakly peraluminous and high-K calc-alkaline with A/CNK values of 0.99-1.20 and high contents of SiO2 (69.86％-70.94％),K2O (3.20％-4.08％),K2O +Na2O (5.61％-7.03％),and belongs to I-type granite.It is characterized by enrichment in LILE (such as K,Rb,Ba,Th,U),and by depletion in HFSE(such as Nb,Ta,Ti,P) with high LREE/HREE ratios of 11.04 -13.13 and moderate negative Eu anomalies (δEu =0.72-0.84).The geochemical characteristics of the Xigongka granodiorite suggested that it was partial melting of crustal components.In combination with previous studies,the Xigongka intrusion was formed in the Late Triassic,which is consistent with the ages of other intrusions in the region.Therefore,they were all formed in the same tectonic environment of post-collision.This finding indicated that the west part of Western Qinling Orogen turned into the tectonic environment of post-collision in the Late Triassic and it also provided new constraints on the tectono-magmatic evolution of Gonghe Basin in Western Qinling Orogen.关键词
锆石U-Pb年龄/地球化学/构造环境/西功卡花岗闪长岩/共和盆地/西秦岭Key words
zircon U-Pb geochronology/geochemistry/tectonic setting/Xigongka granodiorite/Gonghe Basin/western Qinling mountains分类
天文与地球科学引用本文复制引用
杨瀚文,申俊峰,魏立勇,张振,刘满年,冯博鑫,张洛宁..西秦岭西段共和盆地周缘西功卡花岗闪长岩体锆石U-Pb年龄、地球化学特征及其构造意义[J].现代地质,2018,32(2):316-328,13.基金项目
中国地质调查局地质矿产调查项目(1212011220660). （1212011220660）
