摘要
本文根据上海地块的地质演化历史,确认它为外来地体,中生代早中期才汇聚于中国大陆东部。中生代晚期,成为福建—岭南隆起带的一部分,其中局部发育了晚侏罗、白垩纪的断陷盆地,新生代随该隆起带全面下沉,接受沉积。上海地块的地震活动以“频率高、强度低”为特征,地震往往发生在不同方向断裂的交汇处,上海地块上的断裂以 NEE 向和 NNW 向的两组为主,前者具剪切滑移性,后者具压扭性,根据各处发育的断裂规模和地震密度不同,可将上海及其邻区地震划分为四个小区。在一些区内可发生5级以上的较强地震,这是值得人们重视的。
The Pre-Mesozoic Tectostratigraphic layer which can be divided into Pre-Sinian systemlayer and Lower-Paleozoic layer in the Shanghai block is similar neither to that of NorthChina nor to that of Yangtze.This block became an element of Fujian-Linnan upwarpingzone after it had floated from another place and then adhered to the east part of Chinaduring the Triassic to Mid-Jurassic period. The later devoloped NW trending fault cut through the earlier developed NE trendingfault,which was the main fault-group in Mid-Cenozoic.In the Shanghai terrain,the characteristics of the earthquake are of higer frequencybut lower intensity.But as the Lodain-Sinchang NNW trending fault-group is a uniqueearthquake controlled fault in the entire Shanghai block,it can be confirmed that thestronger earthquake may occasionally happen along with it.
关键词
上海
地质属性
地震活动性
a foreign terrain
conjoin or place togather
the quake-bringing fault
faults convergence
the earthquake concentration areas and points
