地质调查与研究2012，Vol.35Issue(2)：109-117,9.
大兴安岭北部永庆林场-十八站花岗岩锆石U—Pb年龄、Hf同位素特征
Zircon U-Pb Ages, Hf isotopic Characteristics of the Yongqinglinchang-Shibazhan Granites in the Northern Da Hinggan Mountains, Northeastern China
摘要
Abstract
The Yongqinglinchang-Shibazhan granites are located in the Eerguna block in the northeastern Da Hinggan Mountains, and mainly consist of granodiorite, with minor adamellite and quartz diorite. The zircon grains separated from the granodiorite sample in the Yongqinglinchang-Shibazhan granites show generally euhe-dral form with fine oscillatory zoning on their CL images, and high Th/U ratios(0.23-1.35), which exhibit the fea- tures of magmatic zircons. LA-ICP-MS zircon U-Pb dating reveals that the Yongqinglinchang-Shibazhan granites emplaced at 443.5-447.5 Ma, belonging to the products of upper Ordovician magmatism, not to the Neoprotero-zoic recognized and categorized by predecessors. Zircon Hf isotope characteristics indicate that two granotoid samples have zircon sill(t) values ranging from-1.1 to +2.4 and -0.4 to +3.6, with model ages from 1.2 Ga to 1.5 Ga. Combined with previous zircon Hf isotope data obtained from Early Paleozoic and Mesozoic granites in the Eerguna block, the authors hold that the granites have the similar model ages although they were formed in differ- ent geological ages. Meanwhile it indicates that the crustal accretion event of Eerguna block occurred mainly in Middle and Neo-Proterozoic period. Previous studies indicate that the Xing' an block accreted in Neoproterozo-ic-Phanerozoic. It suggests that they have the different tectonic natures and evolvement history.关键词
额尔古纳/永庆林场-十八站/花岗岩/U-Pb同位素年龄/Hf同位素/地壳增生Key words
Eerguna/Yongqinglinchang-Shibazhan/granite/U-Pb isotope dating/Hf isotope/crustal growth分类
地质学引用本文复制引用
任邦方,孙立新,程银行,滕学建,李艳锋,郝爽..大兴安岭北部永庆林场-十八站花岗岩锆石U—Pb年龄、Hf同位素特征[J].地质调查与研究,2012,35(2):109-117,9.基金项目
国土资源部大调查项目：兴蒙造山带中古老陆块性质与成矿背景综合研究 （）
