营口—潍坊断裂带新生代走滑拉分—裂陷盆地伸展量、沉降量估算

应用通过营口—潍坊断裂带及相关新生代盆地的地震剖面,采用专业软件分别计算了潍北凹陷、青东凹陷、莱州湾凹陷、黄河口凹陷、渤中凹陷、渤东凹陷、辽中凹陷和辽东凹陷的伸展量及构造沉降量,表明虽然同受断裂带走滑和软流圈上涌控制,但不同区段新生代伸展作用方向、主要发生时间和强度都有差别。南段是南北方向伸展,伸展作用主要发生在古新-始新世孔店组—沙河街组三段沉积时期;中段渤中—辽东湾南部地区具有多向伸展特征,近东西方向和南北方向伸展作用最为强烈,主要伸展作用发生在中-晚始新世、渐新世和新近纪,特别是以新近纪强烈伸展作用区别于其它地区;北段即辽东湾中-北部地区主要是北西—南东方向伸展,主要伸展活动发生在中始新世沙河街组三段和渐新世东营组沉积时期。文章总结了4种不同类型的沉降,指出新生代的构造活动随时间有自南向北推移和自两侧向中间迁移的规律,提出不同方向断裂带的活化和新近纪北东东向新生构造的形成是裂陷强度向中间迁移并产生4种不同沉降类型盆地的原因。

Calculation of extension and subsidence of the Cenozoic pull-apart and rift basins along the Yingkou-Weifang fault zone

A group of Cenozoic basins developed along the Yingkou-Weifang fault zone.Based on seismic sections of intersect the Yingkou-Weifang fault zone,the paper calculated extensional quantities and subsidence rates of 8 Cenozoic rifting or pull-apart sags,namely,the Weibei,Qingdong,Laizhouwan,Huanghekou,Bozhong,Bodong,Liaozhong and Liaodong Sags along the Yingkou-Weifang fault zone.The results indicated that these sags had varied extensional directions,subsidence scales and main rifting periods,although all of them were controlled by strike-slipping of the fault and asthenospheric upwelling in the area.In the southern segment,the N-S extension occurred from Paleocene to Eocene(sedimentary period of the Kongdian Formation and the 3rd Member of Shahejie Formation).In the middle segment(the Bozhong Sag and southern Liaodong Bay),the multi-direction extension occurred mainly in Middle Eocene,Oligocene and Neogene.In the middle-northern part of the Liaodong Bay,the NW-SE extension developed mainly in Middle Eocene(sedimentary period of the 3rd Member of Shahejie Formation)and Oligocene(sedimentary period of the Dongying Formation).To sum up,four types of subsidence curves,and correspondingly,four kinds of Cenozoic basin patterns were presented,which might be resulted from reactivation of Mesozoic faults with different directions and newly generated NEE-striking fault only in the Bohai Bay during Neogene.So,the developing of the rifting or pull-apart basins migrated from the south to the north,and from the both sides to the centre.