延边地区晚三叠世火山岩的岩石地球化学特征及其构造意义

延边地区晚三叠世火山岩主要由安山岩和流纹岩构成，其中包括少量玄武安山岩。火山岩的岩石化学和地球化学研究表明，晚三叠世火山岩属于亚碱性系列，并具有钙碱性系列演化特征，位于中钾和高钾钙碱性岩系列范围。岩石组合、主要元素和稀土元素(REE)等显示晚三叠世火山岩的形成与活动大陆边缘伸展环境有关，它标志着泛太平洋板块(法拉隆板块)对欧亚大陆作用的开始，同时也标志着古亚洲枸造域的结束。

Petro-geochemical characteristics and tectonic significance of Late Triassic volcanic rocks in Yanbian Area, northeastern China

The Late Triassic volcanic rocks in Yanbian Area are mainly composed of andesite,rhyolite,and minor basaltic andesite. The petro-chemical and geochemical data of the volcanic rocks indicate that they belong to subalkaline series and show the evolutional trend of calc-alkaline volcanic rocks, and are characteristics of the medium-K to high-K calc-alkaline series. The rock association, major and rare earth element data of the Late Triassic volcanic rocks suggest that they could be formed under the extensional environment in active continental margin. The formation of Late Triassic volcanic rocks in Yanbian region implies the beginning of the subduction of the Paleo-Pacific plate beneath the Eurasian plate and the end of the Paleo-Asian tectonic system.