营口-潍坊断裂带新构造和新构造活动的再认识

RE-COGNITION OF THE NEOTECTONICS AND ACTIVITIES OF THE YINGKOU-WEIFANG FAULT ZONE

营潍断裂带是郯庐断裂带通过渤海的部分,亦为渤海湾盆地东部构造的重要组成部分,近年来一些研究者从不同角度对断裂带的新构造和新构造活动等进行了不同程度的研究。文中基于以往的工作并结合其他研究者的成果,对该断裂带的新构造和新构造活动及有关问题再次作了分析。渤海地区新构造运动开始于中新世晚期(12~10MaBP),它源自区域地壳水平运动,新构造应力场以NEE-SWW至近EW向水平挤压为特征。营潍断裂带的新构造,主要表现为先存古近纪断裂复活和新构造应力场初始应力作用在其上覆新近系--第四系中形成的构造变形,它以断裂极其发育为特征。NE向斜切营潍断裂带中段的庙西北-黄河口新生断裂带的产生,不仅使营潍断裂带的新构造和新构造活动具分段性,而且使该断裂带的新构造活动显著减弱。渤海东部地震基本沿庙西北-黄河口断裂带分布,营潍断裂带辽东湾段和莱州湾段地震较少且震级小。为究其原因,最后还作了初步的力学分析。

The Yingkou-Weifang fault zone（YWFZ）is the part of the Tanlu fault zone across the Bohai Sea, and is also an important part of the tectonics of the eastern Bohai Bay Basin. Many studies have been carried out on the neo-tectonics and activities of the YWFZ in recent years. In this paper, the neo- tectonics and activities of the YWFZ, and other related issues were studied again, based on our previous work and results of other researchers. The neo-tectonic movement in the Bohai Sea area began in the late Miocene（ 12-10Ma BP） , which originated from the local crust horizontal movement, the tectonic stress field is characterized by NEE-SWW and near E-W horizontal compression. The neo- tectonics of the YWFZ is represented mainly by Neogene-Quaternary deformation, due to rejuvenation of Paleogene faults. Many faults have developed. The neo-tectonics and activities of YWFZ have characteristics of segmentation and weakening, because of the development of the NE-trending Northwest Miao Island-the Yellow River Estuary fault zone, which crosses the YWFZ. Earthquakes in the east of Bohai Sea are distributed along the Northwest Miao Island-the Yellow River Estuary fault zone, only few and small earthquakes along the Liaodong Bay and the Laizhou Bay section of the YWFZ. We made a preliminary analysis of the mechanics for this phenomenon.