Late Paleozoic Tectono-Magmatic Evolution in Bogda Orogenic Belt, Xinjiang: Evidence from Geochemistry of Volcanic Rocks
详细信息
- 责任者：Wang Jinrong (Earth and Environmental Sciences ; Lanzhou University ; Lanzhou 730000 ; China) ; Li Taide
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(4)
- 关键词：双峰式火山岩 ; bimodal volcanic rocks ; 岩石地球化学 ; lithogeochemistry ; 博格达山 ; Bogeda Mountains
- 页码：p.1103-1115
- 图表：illus., 2 tables, 70 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Late Carboniferous bimodal volcanic rocks and Early Permian acidic volcanic rocks were revealed recently in Yiqi-Xiaohongxia of the northern margin of the eastern section of Bogda Mountain, Xinjiang, but in petrogenesis the former different from those in the Qijiaojing Region south to the studied area. The bimodal volcanic suite in the studied area is composed of basalts and a less amount of rhyolites. The basalts have high-Al, -Mg, and -Na, but low-K contents and low K2O/TiO2 and K2O/P2O5, belonging to tholeiitic series, and indicating no fractional crystallization of plagioclase during the basaltic magmatism. The basalts have geochemical features indicative of basalts formed within continent and originated from depleted mantle, and that the continent crust became thinner and thinner due to extension for a long time.The rhyolites of bimodal volcanic rocks show they are high-K calc-alkaline series and originated from the melting of lower crust with plagioclase as an important relic mineral in the source. The studied results indicate that magmatism of the Bogda rifting started in the Early Carboniferous ,ended in the end of Late Carboniferous, and then transformed into the post-orogenic evolution of the extension in the end of Early Permian.