天津地区的断裂构造特征

通过重力资料的处理解释,对天津地区的断裂构造有了一定的认识,认为、断裂为该区的主控断裂,具有规模大、控制性强、长期继承性活动的特点。、级断裂多为控制、分割构造单元内部不同类型构造（区带）的分界线,对局部构造单元的形成、发展、演化及沉积建造起着重要的控制作用。多数断裂的活动具有阶段性、长期继承活动的特征,其活动性在不同发展阶段或同一阶段内有所不同。形成了以规模较大的断裂为主干的断裂构造系统,平面上交织为以北东向、北西向、近东西向为主,南北向为辅的构造格架,断裂均为隐伏断裂。同时,推断该区、级断裂生成较早,多为古生代、中生代,多数断裂自形成后经过多次构造运动的改造具有多次复活、长期活动的特点。、级断裂生成较晚,多为古近纪,活动强烈,古近纪为强烈活动时期。

Characteristics of Fault Structure in Tianjin Area

Having processed and interpreted some gravity data,we have understood,to a certain degree,of the fault structures in Tianjin area.Fault Ⅰ and Ⅱ are the master faults in the area,they are large in scale,good in controlling,and long period of time in inherited activity.In addition,they are mainly the boundary lines for different kinds of structural zones or divide this area into sub-structural units.So these faults play an important controlling role for the formation,development,and evolution.Most of the faults are characterized by stages/phases and long-term inherited activity,although the activity is different in different development period or in the same period,forming a fault system mainly composed by large-scale faults.Horizontally,this structural frame is mainly the NE,NW,and Nearly EW directions,with the SN being the secondary.At the same time,we infer that the Ⅰ,Ⅱ grade fractures were formed during the earlier time,mostly Paleozoic,Mesozoic generation and that the majority of fracture after the formation of the transformation of repeated tectonic movements have repeatedly rise and the characteristics of long-term activities.Ⅲ,Ⅳ-level of fault were formed later,mostly in the Paleogene and is characterized by intense activity,with the Paleogene period being the intense activity.