摘要
本文利用 R_1—R_2图解、微量元素图解、数学地质,结合现代地震资料分析结果,通过对地动力条件、岩浆活动和沉积建造等方面分析认为:张家口火山岩形成于具裂谷性质的构造环境。
Zhangjiakou is the area of the eastern China where Mesozoic volcanic rocks are well developed.Volcanic rocks composed of rhyolite and trachyte.Regional tectonic enviroment of volcanic eruption in this district has always been debated. In this paper,a comparison of volcanic rocks of Zhangjiakou with volcanic rocks of the typical areas in the world in terms of chemical features.Q-type cluster analysis and discrimination diagrams of trace elements of the volcanic rocks has been made,these fea- tures of Zhangjiakou volcanic rocks are similar to those of post-orogeny rift belt.Ac- cording to above-mentioned comparison and magmatism,sedimentation,regional stress condition and earthquake material analyses,it is infered that Zhangjiakou volcanism took place in the infancy of post orogenic rifting bect.
