黄骅坳陷南部滩海区中生界构造与演化

STRUCTURAL PATTERN AND EVOLUTION OF THE MESOZOIC STRATA IN THE BOHAI BAY BASIN RANGE:A CASE FROM SOUTHERN SHORE OF MIDDLE RANGE OF THE HUANGHUA DEPRESSION

渤海湾盆地区中生界构造演化与样式始终不明朗,中生代该区处于整个华北克拉通东部高原的核心部位。其构造演化研究对深入理解这个高原从形成至垮塌的过程至关重要。同时,中生界也是近年来中国东部深部油气勘探的主要目标。黄骅坳陷南部滩海区不仅是大港探区中生界潜山油气的重要勘探区,而且处于渤海湾盆地中新生代构造格局转换部位,具有重要研究价值。利用大量地震剖面,系统进行了中生界残存展布规律的分析,进一步划分了该区构造单元,探讨了该区中生界构造演化过程。特别是,以羊二庄断层为界,研究区可以分为两个构造区,东南区构造相对简单;西北区构造复杂,既继承了印支期东西向构造格局,又经历燕山早、中期走滑挤压和燕山晚期及新生代的伸展走滑,还产生了强烈的滑断构造。羊二庄断层是在印支期构造的基础上发展起来的一组剪切断裂,在燕山中期经历了挤压走滑,在燕山晚期和新生代经历右行伸展运动而形成的呈NE向的复杂断层系。可见羊二庄断层的演化控制了该区中生界的构造格局和演化。

Bohai Bay basin range is located at the center of a Mesozoic plateau in eastern North China craton in Mesozoic. Its structural evolution is a key problem to understand process from formation to collapse of this plateau. Moreover, these Mesozoic strata are important oil-gas exploration objectives in eastern China in recent years. However, structural pattern and evolution of this region are not clear up to the present. The south shore of Huanghua depression is not only an important and new oil-gas exploration area for Mesozoic buried hill in the Dagang exploration area, but also is located at spatial and temperal switch site of Mesozoic-Cenozoic structural patterns of the Bohai Bay basin. Therefore, the study area is of important implication for research. A large number of seismic profiles were interpreted to analyze distribution rule of relic Mesozoic strata. Furthermore, we subdivided the structural units in the study area and discussed its Mesozoic structural evolution. Taking Yang＇erzhuang fault as a border, we divided the study area into a northwest region and a southeast region. Structures in the former is more complex than in the latter. The northwest region inherited EW Indosinian structural pattern, and also experienced slip and compression during the early and middle Yanshan movement. Then strike-slip and intense slip-break structures occurred during Yanshan movement and Cenozoic. The Yang＇erzhuang fault is a strike-slip fault system which evolved from Indosinian period and then experienced compression and strike slipping in middle Yanshan movement, and went through dextral slipping during Yanshan movement and Cenozoic. These processes indicate that the Yang＇erzhuang fault controls the structural pattern and evolution of Mesozoic strata in this area. In summery, structural evolution in the study area is an epitome of tectonic evolution of the Bohai Bay basin.