摘要
对燕山地区中生代板内变形的研究进展进行了总结,确定翁文灏75年前识别和提出的燕山运动A幕、B幕和中间幕发生在侏罗纪。侏罗纪的构造变形最终塑造了东西向燕山褶皱-冲断带的格架。通过对典型盆地的分析,燕山运动A幕以髫髻山组安山岩之下的角度不整合为标志,时限为160Ma±5Ma前,时期为中侏罗世龙门期—九龙山期,时代推测在175～160Ma之间。中间幕以髫髻山组和兰旗组火山岩为代表,时代约在165～156Ma之间。B幕强烈的冲断形成了土城子组和后城组的粗碎屑堆积,时限在135Ma±1Ma前,时代为156～139Ma。白垩纪早期,区域变形逐渐以伸展为主,古地理—古环境明显改变,火山喷发频繁、强烈,构造变形较弱。显然,早白垩世的构造发展已不属于燕山运动的范畴。燕山运动A幕是燕山板内变形带最主要的构造事件,也是东亚构造体制转变的标志。
Through a review and summing-up of the progress in the study of the Mesozoic intraplate deformation in the Yanshan area, it has been determined that phases A and B and the intermediate phase of the Yanshan movement recognized and proposed by W.H. Wong 75 years ago all took place in the Jurassic. The Jurassic tectonic deformation finally formed the framework of the E-W-trending Yanshanian fold-thrust belt. Based upon an analysis and study of regional typical basins, it is found out that phase A of the Yanshanian movement- marked by angular unconformity below andesites of the Tiaojishan Formation- is prior to 160±5 Ma, the geological phase is during the Middle Jurassic Longmenian-Jiulongshanian, and its inferred age is 175-160 Ma. Phase A was the most important tectonic event in the Yanshan intraplate deformation belt and is the indication of the transformation of the Eastern Asian tectonic regime. The intermediate phase is represented by volcanic rocks of the Tiaojishan and Lanqi formations, ranging in age from 165 to 156 Ma. Intense thrusting in phase B gave rise to coarse clastic deposits of the Tuchengzi and Houcheng formations. Its date is prior to 135±1 Ma and its isotopic ages ranging from 156 to 139Ma. From the Early Cretaceous on, regional deformation was gradually dominated by extensions then the tectonic environment changed significantly, volcanic eruptions took place repeatedly and strongly and tectonic deformation was relatively weak. It is evident that the tectonic development that began in the Early Cretaceous does not belong to the Yanshan movement.
出处
《地质通报》
CAS
CSCD
北大核心
2004年第9期854-863,共10页
Geological Bulletin of China
基金
国家自然科学基金重点项目(40132020)
中国地质调查局地质调查项目(DKD2001008)资助。
关键词
燕山
陆内变形带
构造事件
侏罗纪
燕山运动
Yanshan
intraplate deformation belt
tectonic event
Jurassic
Yanshan movement
