论文部分内容阅读
华北地区的地质构造具有典型的断块系统特征.用非连续形变分析(DDA)方法模拟了该地区的长期形变,包括无震断层滑动和断块形变。通过模拟我们发现:(1)断层沿不同方向的滑动通常与 ENE-WSW 向的区域构造挤压一致。(2)如果沿主要活动断层的平均无震滑动速率与跨断层大地测量观测的结果一样是每年零点几毫米的量级,那么断块内的典型应变速率是10~(-8)/a 或更小量级,所以一些小区域的观测报告所得的应变率10~(-6)/a 就不能代表该地区的形变速率。(3)对一条断层, 由相邻断块内刚体旋转引起的断层滑动方向可能与区域构造挤压引起的滑动方向相反。但由于由构造挤压引起的滑动量级远大于由断块旋转引起的断层滑动,因此,一般来讲,断层滑动图像总体上与这一地区构造挤压方向一致.也就是说,由区域挤压引起的滑动控制了整个滑动情况。(4)根据(3),某些观测到的与 ENE构造挤压方向相反的滑动可能是由某些更为局部化的因素引起的,没有构造意义.
The geological tectonics in North China has typical characteristics of block systems, and the discontinuous deformation analysis (DDA) method is used to simulate the long-term deformation in this area, including the faultless slip and block deformation. We found through simulation: (1) Slips along different directions are usually consistent with the regional structural extrusion in the ENE-WSW. (2) If the average rate of anomalous slip along the main active fault is on the order of a few tenths of a millimeter each year, as is the case with cross-fault geodesy observations, the typical strain rate within a fault is 10 -8 / a or Therefore, the strain rate of 10 ~ (-6) / a obtained from some small area observation reports can not represent the deformation rate in this area. (3) For a fault, the direction of fault slip caused by the rotation of a rigid body in an adjacent fault block may be opposite to that caused by squeezing of the regional structure. However, since the magnitude of slip caused by tectonic extrusion is much larger than the fault slip caused by the rotation of the fault block, the fault slide image is generally consistent with the tectonic extrusion direction in this area, that is, Sliding caused by pressure controls the entire sliding condition. (4) According to (3), some of the observed slippage in the opposite direction to that of the ENE tectonic extrusion may be caused by some more localized factors, without constructive implications.