下扬子盆地黄桥地区构造演化

本文利用平衡剖面法对下扬子盆地黄桥地区连井大剖面进行构造演化分析,将黄桥地区构造演化划分为三个阶段：①印支运动前平稳隆降阶段：构造形态简单、平稳;②印支运动-燕山早、中期运动挤压推覆阶段：三叠纪末,本区遭受最强烈的构造运动,强烈的隆升、发育一系列推覆构造,在平面上具有明显的对冲构造特征。断层及地层褶皱量在18.3 km。③燕山晚期-喜山期拉张裂陷阶段：晚白垩-早第三纪时,下扬子地区应力场由原来的挤压转变为SE-NW向的拉张,表现为整体下降,广泛接受了上白垩统沉积,该阶段构造活动较强,致使先期逆冲断层发生构造反转,地层拉张量3.9km。拉张正滑大断层既控制着下第三系的沉积,又改造中古生界推覆冲褶构造,形成今日新面貌。致使黄桥地区构造形成由一系列的断垒和断鼻构造。

Tectonic Revolution of Huangqiao Area in Lower Yangtze Basin

This present paper analyzed the tectonic revolution of connecting-well section of Huangqiac Area in Lower Yangtze Basin by the method of equilibrium profile, then divided it into three stages.（1） Smoothly sink-uplift stage before Indosinian, the structural form was simple and steady;（2）Extrusion and thrust movement stage between Indosinian and early-middle Yanshan ：last phase of Triassic, this area underwent the strongest tectonic movement, uplifted intensely, developed series of thrust structure, characterized with distinctive ramp structure in the plane, the folding amount of fault and strata was 18.3 km; （3） Extensional and chasmic stage between late Yanshan and Himalayan. late Cretaceous- early Triassic, the stress field of Lower Yangtze transformed from former extrusion to extension of SE-NW direction, the showing was mass sinking, deposited Upper Cretaceous widely, the tectonic movement of this stage was so strong and structure reversion of former thrust fault happened, the extension amount of strata was 3.9km. The extensional normal-slip fault controlled the deposition of Lower Tertiary and also modified the thrust fold structure of Middle Palaeozoic, then the present apperenee was formed. A series of fault host and fault-nose structure were developed in Huangqiao Area.