• 责任者：Liu Jianfeng (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Li Jinyi
• 刊名：Geological Bulletin of China
• 出版年：2013
• 卷期：32(2/3)
• 关键词：火山岩 ; volcanic rocks ; 铀—铅计时 ; U-Pb dating ; 内蒙古 ; Inner Mongolia
• 页码：p.267-278
• 图表：illus., 3 tables, 67 refs.
• 分类号：0801
• issnNo：ISSN1671-2552
• isbnNo：CN11-4648/P

Zircon LA-ICP-MS U-Pb dating of the Badangshan rhyolitic tuff from Jiefangyingzi area in northern Chifeng City of Inner Mongolia was carried out in this paper. The study area is located on the northern margin of the North China craton tectonically. The dating result reveals that the volcanic rocks were formed in early Devonian （403.7Ma±1.3Ma） rather than in Silurian as previously thought. The volcanic rocks are characterized by high SiO2 （76.90%-78.74%） and Al2O3 （12.11%-12.86%）, low CaO （0.13-0.74） and variable K20 （1.68%-4.01%） and Na20 （2.23%-5.02%）, with the aluminum saturation index （A/CNK） being 1.07-1.52. Chemically, they belong to calc-alkaline series and peralurrfinous volcanic rocks. Zircon εHf（t） values are negative （-22.0--16.4） and two stage model ages （TDM2） are from 2423Ma to 2770Ma, indicating that the volcanic rocks originated from partial melting of the ancient crustal materials of the North China craton. A synthetic study of the geochemical characteristics of the Badangshan volcanic rocks and the regional geological data reveals that the volcanic rocks were formed in the setting of late Early l~aleozoic collision between the Bainaimiao island arc and the northern margin of the North China craton.