断层活动时间的同步性特点

断层活动是地壳应力释放等的一种表现。其主要应力一般通过区域性断层释放,小断层除释放剩余应力外也可是前者活动时的牵动。因此,在一个局部地区内断层活动时间常具有同步性特点。对化稍营地区大、小断层的研究表明,传统法确认油房断层被上更新统复盖,其最后一次活动时间在晚更新世以前;应用热释光、铀系法与显微构造分析结合,研究发育在基岩中的壶流河断层、F_(207)断层、F_(214)断层和F_(213)断层,确定其最后一次较强烈活动为距今20～30万年前。两者结果的吻合,证明了断层活动时间的同步性特点。

SYNCHRONEITY OF FAULT ACTIVITIES

Fault activity is a result of the release of crustal stress. The regional faults usually releave the major part of the stress, and the minor faults in a certain region usually release the residual stress and are controlled or constrained by the regional fault movement. The fault activity in a certain region is characterized by a synchroneity.The authors have studied in detail the major and minor faults in Huashaoying area. Geologic investigation has found that the Youfang fault, which in one of the major faults in the area, is covered by Late Pleistocene deposits. It is concluded that the last strong movement along the fault occurred befor Late Pleistocene. Microstructural analysis and thermoluminescent and uranium-series datings have determined that the ages of the last strong movement along Huliuhe fault (another major fault in the area) and minor faults F207, F214 and F213 are about 200-300 thousands years ago. The consistency of these age data indicates a synchroneity of the fault activities in the area.