郯庐断裂带中段安丘—莒县断裂淮河—女山湖段几何展布

Geometric Distribution of Huaihe—Nvshan Lake Section of Anqiu—Juxian Fault in the Middle Part of Tanlu Fault Zone

郯庐断裂带中段最新活动的安丘—莒县断裂(命名为F5断裂)为中国东部地区重要的地震活动断裂。已有研究表明,F5断裂向南已延伸进入安徽境内的淮河—女山湖之间,但该段的具体几何展布还存在以下问题未解决:一是F5断裂以东的紫阳山东侧断裂是否属于F5断裂分支;二是F5断裂向南是否延伸至女山湖北岸。为解决以上问题,本次工作基于遥感解译、地质地貌调查、探槽开挖及断错地层年代样品测试等方法,对紫阳山东侧断裂及女山湖北岸一带断裂开展了研究。结果表明,紫阳山东侧断裂发育时代较老,在早、中更新世发生过强烈逆冲挤压运动,晚第四纪以来不活动,该断裂不属于F5断裂分支;郯庐断裂带在女山湖北岸上詹村一带断错了晚更新世地层,该处断裂为F5断裂向南的延伸部分;F5断裂已完全贯穿于淮河—女山湖之间,断层迹线单一、连续,段落总长度约20 km。文中还讨论了F5断裂向南应该终止于女山湖至明光市一带,断裂终止受区域古老构造格局控制,表明该断裂既有新生性又有继承性。

The latest active Anqiu—Juxian fault named F5 fault in the middle section of the Tanlu fault zone is an important seismically active fault in the eastern China. The present studies have shown that the F5 fault has extended southward into the Huaihe—Nvshan Lake in Anhui province, however, the specific geometrical distribution of this segment still has two major unresolved problems. Firstly, does the eastern fault of the Ziyang mountain belongs to the branch of F5 fault? secondly, does the F5 fault extend south to the northern shore of Nvshan Lake? In order to solve these problems, based on the methods of remote sensing interpretation, geomorphological survey, trench excavation and dating of faulted strata, we conducted research on the faults on the eastern side of Ziyang mountain and the faults along the northern shore of Nvshan Lake. The results show that the eastern fault of the Ziyang mountain developed at an older age, and experienced a strong thrust compression movement in the early and middle Pleistocene. It did not active since the late Quaternary and does not belong to the F5 fault branch. The Tan-Lu fault zone faulted the Late Pleistocene stratum in the ShangZhan area on the northern shore of Nvshan Lake. The F5 fault has completely penetrated between the Huaihe River and Nvshan Lake, its trace is single and continuous, with a total length of about 20 km. It has been discussed that the F5 fault could terminated southward from Nvshan Lake to Mingguang City. The termination of the fault is controlled by the regional ancient structural pattern, which indicating that the fault is both new and inherited.