基于地球物理、钻井等资料,运用地层对比、孔隙度拟合以及盆地模拟的原理与方法,恢复出济阳坳陷西南端沙三段(Es3)剥蚀地层厚度及原始地层厚度,进行构造沉降量和拉张系数计算,探讨沙三段沉积期盆地构造活动特征及主控应力场。结果表明:沙三段沉积期,济阳坳陷西南端沉积中心的延伸方向宏观上呈 NE-SW 向展布,局部表现为近 SN 向延伸;该时期盆地的伸展强度并不均匀,表现为中部强,向 NW、SE 方向减弱;伸展作用宏观上受控于NW-SE 向伸展应力场,可能受基底断层走滑的影响,局部伸展受控于近 SN 向应力场;济阳坳陷沉积中心展布方位前后经历了不同阶段近 EW 向、近 EW 与 NE 向共存及 NE 向展布的递进演变过程,但最终受控于 NW-SE 向伸展应力场。
Using the physical geography and drilling well data, the eroded and original overbudens during the third Member of Shahejie Formation (Es3 ) in extreme southwest Jiyang Depression were estimated with a series of methods such as strati-graphic correlation, porosity fitting and the principle and methods of basin modeling. The tectonic subsidence and the exten-sion coefficient were then calculated, and the character of sedimentation and its main controlling factor were discussed. The results are as follows. First, the depocenter is NE-SW trending as a whole, but is locally nearly south-north trending during Es3 stage in the extreme southwest Jiyang Depression. Second, the extensional level is not uniform: the center is stronger and it weakens toward northwest and southeast. The extension is controlled by NW-SE trending stress field in general, and by south-north trending locally resulting from the slip of the basement faults. Lastly, the spatial distribution of the depocenter in Jiyang Depression has gone through the progressive development from east-west trending in the early stage, the coexistence of nearby east-west and north-east trending in the middle stage, and north-east trending finally during Es3 stage. The whole sys-tem is however controlled mainly by NW-SE trending extensional stress field.