郯庐断裂带的活断层与郯城8.5级地震的构造条件

THE ACTIVE FAULTS IN THE TANLU FAULT ZONE AND THE STRUCTURAL CONDITIONS OF THE TANCHENG EARTHQUAKE (M=8.5)

摘要:

郯庐断裂带是中国东部一条结构复杂、规模巨大的北北东向断裂构造带,在我国境内长达2400多公里。这条断裂带在地质时期经历了左行平移、岩浆活动、裂谷作用、挤压揉皱、逆冲右旋走滑等复杂的运动过程。新构造期以来具明显地分段活动特征,其中沂沭断裂段新活动最显著,直到第四纪晚期仍有长达360km的断裂活动带。断裂活动的特点,表现为空间分布的迁移性,活动时间的阶段性、间隔性,活动方式是以粘滑为主,通过群集和长间隔的大震破裂方式进行。 1668年郯城8.5级大震和几次全新世古地震事件,在沂沭活断层的中段重复发生,是由特殊的构造条件所决定的,分析深浅部构造特征、介质条件,推测郯城马陵山地段在中地壳以上形成了一个新的推覆构造体。在区域应力场的作用下,这个推覆体沿活断层带向南西运动,1668年郯城8.5级地震与几次古地震事件的发生很可能与这个推覆构造的活动密切相关。

Abstract:

The Tanlu fault zone, a NNE fault zone in east China, has a complex internal structure and a broad scale. It is about 2400km long within China. This fault zone has experienced a series of very complex tectonic movements with left lateral strike-slipping, magma activity, rifting, compresso crumpling and right-lateral strike-slipping and thrusting o In the neotectonic stage, the segmented activities are obvious along the Tanlu fault zone. Along the Yishu fault segment the new activity of faulting is strikingi...