中国北方半干旱区第四纪晚期构造活动性

近20万年以来,中国北方半干旱区的构造活动性是非常明显的。在这一地区发现了许多第四纪晚期的活动构造,例如,正断层、逆断层、走滑断层、褶皱、拗陷、隆起、古地震构造、火山构造、构造地貌等。在构造地块中部,垂直运动的最大幅度大约是88-132m,其平均运动速率约0.44-0.66mm/a;而在地块周边的活动构造带,则最大垂直运动幅度为210-343m,平均运动速率为1.05-1.77mm/a。构造运动的强度和速率是不断增大的。主压应力表现为NE-SW和近EW方向。自200kaBP以来,构造活动可以划分为6个阶段,其年龄分别为200、100-70、50-30、10-7、0.7和0.3kaBP。其中100-70kaBP和50-30kaBP的两次运动是第四纪晚期最强烈的两次运动。中国北方半干旱区的构造演化是与青藏高原的阶段性隆升密切相关的。构造活化是中国北方干旱-半干旱区形成演化的重要控制因素之一。 

TECTONIC ACTIVITY IN SEMI-ARID AREA OF NORTH CHINA DURING LATE QUATERNARY

The last 0.2 Ma has witnessed very obvious tectonic activity in the semi-arid area of North China.There are many active structures dated as of late Quaternary age in the area,such as normal fault,reverse fault,strike-slip fault,fold,sag,uplift,tectonic landform,tectonic terrace,fossil earthquakes and volcanic structures.The maximum amplitude of the vertical movement is about 88-132m with an average rate of 0.44-0.66 mm/a in the centre of tectonic blocks,and in the active tectonic zone around these blocks the maximum amplitude is about 210-343m with an average rate of 1.05-1.72mm/a,the intensity and rate of the movement contimually increasing.The principal compressive stress trends NE SW and E W.The tectonic activity in the last 0.2 Ma may be divided into 6 stages with ages of about 200,100-70,50-30,10-7,0.7 and 0.3 kaBP,respectively.The most intensive tectonic movement in the late Quaternary fell in the periods of 100-70 and 50-30kaBP.The tectonic reactivation in the semi-arid area of North China is correlative with the uplift of the Tibetan Plateau,serving as one of the controlling factors in the formation and evolution of the arid and semi-arid areas of North China.