山东地区地面与隐伏伸展构造研究

RESEARCH ON SURFACE AND SUBEWRFACE EXTENSIONAL STRUCTURES IN SHANDONG PROVINCE

中、新生代以来，中国东部地壳一直处在引张应力作用下。在这种应力背景下形成的渤海湾盆地济阳彻陷内及其外围伸展构造十分发育。将露头剖面与地震剖面相结合，归纳研究区伸展构造发育的特征，建立本区伸展构造的几何模型为基础，应用平衡剖面的基本原理对地质剖面进行计算，不仅可以求得与拉伸活动有关的一系列参数，而且还可以比较准确地获得各地质历史时期的构造恢复剖面。经对阳信凹陷两条剖面进行计算，分析结果认为：该凹陷最后一次断陷期始于孔二段，孔一段至沙四下段时为断陷活动最强烈的时期；沙四上段至沙三段时断陷活动已趋缓和；沙二段至东营组时期断陷活动更显微弱并开始向坳陷阶段转化。

The crust of east China has been affected by extensional stress since the Mesozoic-Ceno-zoic. Ectensional structures developed widely in the Jiyang depression and its surroundings.After analysing outcrop sections and seismic profiles,we can sum up the characteristics of ex-tensional strucyures and construct a geometric model of extensional structures in the studyarea. Not only can a series of parameters related to extensional activities be acquired,but alsocan the restored sturctural sections in different geological ages be obtained by using thd basicmethod of balanced-section based on the model,In terms of the calculation of two profiles inthe Yangxin sag of the Jiyang depression,the analysis results ane:the last rifting stage ofthe sag began form the second member of thd Kongdian lormation,the rifting actibity wasstrongest during the first member of the Kongdian formation and the lower part of the foruthmember of the Shahejie formation,tended to relax form the upper part of thd fourth memberof the Shahejie formation,and became much weaker in the second member of the Shahejieformation and thd Dongying formation which were thd transition stage form riftiong to sub-siding.