关键词: 郯庐断裂带, 第四纪, 综合构造解析, 活动习性

Abstract: Remote sensing analysis of tectonic landforms revealed that the Baishan (Lujiang County)-Sapu (Tancheng County) segment of the Tancheng-Lujiang Fault zone appears as a series of parallel faults. Field investigation has confirmed that these parallel fault series are active fault. Moreover,in-situ observation of fault profiles,as well as microstructural analysis of samples collected from the faults reveal that stick-slip and creep-slip deformation have occurred alternately along the Baishan-Sapu segment of the Tancheng-Lujiang fault zone since late Quaternary. In Ketan-Sapu area,the youngest drainage system was dextrally offset by the NE-trending faults. Microscopic observation and dating of the samples collected from the fault show that during Quaternary time the deformation along the fault was characterized by brittle-ductile transition,and the strongest faulting event occurred in Early-Middle Pleistocene. The dating results of fault gouges collected from Baishan profile indicate that this fault segment had been strongly active during Middle-Upper Pleistocene. SEM and optical microscopic observations also show that stick-slip and creep-slip deformation had alternately occurred along this fault segment,and the stick-slip deformation occurred earlier than the creep-slip deformation. In consideration of the distortion of drainage system and the fact that minor earthquake occurred frequently along this fault segment in recent years,it can be postulated that the recent movement along the fault has been dominated mainly by creep-slip,that is to say that the accumulated stress on this segment has been released slowly by creep slip or micro-earthquake. Therefore,it is unlikely that a strong earthquake will occur on this fault segment in the near future.

Key words: Tancheng-Lujiang fault zone, Quaternary, synthetic structural analysis, fault activity