北京西山东岭台组(J_3d)火山岩的成因及其构造环境探讨

Discussion on the origin of volcanic rocks of Donglingtai Formation in Beijing Xishan Mountain and its geological setting.

通过岩石学、岩石化学、地球化学和同位素的研究 ,作者认为北京西山东岭台组火山岩的主要起源于下地壳上部岩石的部分熔融 ;火山岩形成的构造背景为陆内造山带的拉张环境 ,与中生代古太平洋板块向亚洲板块斜向板块俯冲没有直接关系 ;由于晚侏罗世 -早白垩世燕山地区处于拉张状态 ,造成上地幔上部岩石的部分熔融 。

Based on the studies of petrology, petrochemistry, geochemistry and isotopes, the authors think that the volcanic magmas of Donglingtai formation were mainly generated from partial melting in the upper part of lower crust. The geological setting of volcanic rock was extensive in intracontinental orogenic zone and was not associated with the subduction of the Pacific Plate beneath the Asia Plate during Mesozoic. As a result, the upper mantle melt and basaltic magmas had been generated, and the lower crust partial melting and the formation of magmas of Donglingtai formation were caused by the underplating and middleplating basaltic magmas.