柳河县阎家街地区早寒武世馒头组东热段英安质火山岩的发现及意义

在样子哨古生代向斜盆地东翼寒武纪馒头纽东热段地层剖面中发现一套英安质火山岩,呈薄层状夹杂于紫色含石盐假晶钙质粉砂岩中.岩石化学、稀土元素特征反映本区英安质火山岩具有非造山带陆内稳定构造区和造山带活动大陆边缘构造区过渡类型的特点.可能是华北地台北缘由被动型大陆边缘转化为活动型大陆边缘的一种陆内响应.该套火山岩的发现对研究和恢复早寒武世华北地台北缘的构造演化史具有重要意义.

The discovery and significance of dacite volcanic rocks of the Dongrong block, Mantou Formation in early Cambrian in the Yanjiajie, Liuhe County

In regional geologic survey in the Liuhe area by the Third Geological Survey, Bureau of Geology and Mineral Resources of Jilin Province, 1993-1995, a set of dacite volcanic rock was discovered in the Dongre block stratigraphic cross--section, Cambrian Mantou Formation, eastern part of the Paleozoic synclinal basin in the Yangzishao, showing thin layer like and mixing up with violet calcareous siltstone with halite pseudocrystal. Petrochemistry and rare earth element characteristics show that the dacite volcanic rock in the study area has some characteristics with nonorogenic zone stable intracontinetal structure area and intermediate orogenic zone active continental margin structure area. It is probable that is a continental change of the northern margin of the North China platform that transforms passive continental margin into active continental margin. The discovery of the volcanic rock contributes a vast amount of study content of the Dongre block, which has an important significance for studying and recovering structural evolution of the early Cambrian, north margin of the North China platform.