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节理统计、断层、褶皱和震源机制解析等研究表明 ,兰州地区第三纪以来的构造应力场主压应力轴倾角在陡—缓交替过程中逐渐变陡 ,作用方向由SN向、NW—SE向转变为NE—SW向。第三纪时期构造应力场的逆时针运动是地块在该时期作逆时针旋转运动的结果 ,早—中更新世之交出现了青藏高原构造作用的重要转型。进入到EW向伸展机制下的构造变形时期 ,研究区地壳运动以抬升为主 ,但抬升运动与水平运动之间是有机地结合在一起的。经过每一次水平运动 (或抬升运动 )后 ,就出现一个调整时期 ,地壳运动与前一次的运动形式相对应 ,为抬升运动 (或水平运动 )。
The statistics of joints, faults, folds and focal mechanism analysis show that the tectonic stress field of the tectonic stress field in Lanzhou area changed steeply during steep-slow alternation process from SN to NW-SE Change to NE-SW direction. The anti-clockwise movement of the tectonic stress field in the Tertiary Period is the result of anticlockwise rotation of the block during this period. An important transformation of the tectonic function of the Tibetan Plateau occurred at the turn of the Early-Middle Pleistocene. During the tectonic deformation under the EW extension mechanism, the crustal movement in the study area is mainly uplifted, but the uplift and horizontal movement are organically combined. After each horizontal movement (or uplift movement), an adjustment period occurs. The crustal movement corresponds to the previous movement form and is uplifting (or horizontal movement).