郯庐断裂南段怀远—池河北西向断裂的第四纪活动性——来自韭山东北缘的地质证据  

Quaternary activity of the Huaiyuan—Chihe fault on southern section of the Tan-Lu fault zone——Geological evidence from the northeastern margin of Jiushan Mountain

作　　者：方良好 路硕[1,2] 疏鹏 潘浩波 戚浩[1,2] 王扬帆 汪凡[3] FANG Lianghao;LU Shuo;SHU Peng;PAN Haobo;QI Hao;WANG Yangfan;WANG Fan(Anhui Earthquake Agency,Hefei,230031;Mengcheng National Geophysical Observation,Mengcheng,Anhui,233500;Anhui Earthquake Disaster Prevention Center,Hefei,230031)

机构地区：[1]安徽省地震局,合肥230031 [2]安徽蒙城地球物理国家野外科学观测研究站,安徽蒙城233500 [3]安徽省震灾风险防治中心,合肥230031

出　　处：《地质论评》2022年第6期2248-2258,共11页Geological Review

基　　金：中国地震局地震科技星火计划项目(编号:XH20027Y)的成果。

摘　　要：怀远—池河断裂与郯庐断裂带南段相交,处在郯庐断裂带活动性逐渐减弱的地段。为获取断裂活动的地质证据,选取安徽韭山东北缘进行地貌调查、探槽开挖、年龄样品测试等工作。研究表明,韭山东北缘的线性地貌受断裂活动控制,在调查揭示的多个剖面中,断层表现出一致的活动性质,走向NW,倾向NE,倾角70°左右,具有正断性质;断层垂直断距在第四系中由下往上逐渐变小,直至消失在第四纪覆盖层中,说明断裂具有多期活动,进入中更新世后活动性逐渐减弱。通过跨断层探槽剖面分析及测年结果可知,断层最新活动错断了中更新世地层,上覆的中更新世顶部地层及晚更新世地层未受影响,说明该断裂是一条中更新世断裂,晚更新世以来不活动。怀远—池河断裂的活动情况与其所在地区的新构造环境有关。郯庐断裂带是本区规模最大的控制性构造,它的活动性对区内其他断裂具有重要影响,断裂带明光以南段最新活动时代为中更新世,受其影响,与它相交的怀远—池河断裂最新活动时代也表现为中更新世。这或是蚌埠—凤阳地区以中小地震活动为主的一个构造背景。The Huaiyuan—Chihe fault intersects with the southern section of the Tan-Lu(Tancheng—Lujiang)fault zone,and is located in the section where the activity of the Tan-Lu fault zone gradually weakens.In order to obtain reliable geological evidence of activity of the Huaiyuan—Chihe fault,geomorphologic survey,trench excavation and sample age testing were carried at the northeastern margin of Jiushan Mountain in Anhui.Our study shows that the linear landform of the northeastern margin of Jiushan Mountain is mainly due to activity of the Huaiyuan—Chihe fault.In the multiple profiles in our survey,the fault show consistent features.The fault strikes NW,dips to NE with a dip angle of~700 and has normal faulting component.The vertical fault throw of the fault is larger in the old strata while becomes smaller in the new strata and disappeared in the Quaternary layer.It shows that the fault has multi-period activities and its activity gradually weakens since middle Pleistocene.Through analysis of trench profile across the fault and dating,the fault had displaced Middle Pleistocene strata,the overlying top strata of Middle Pleistocene and Late Pleistocene strata are not affected,indicating that the fault should be a Middle Pleistocene fault and has been inactive since the Late Pleistocene.The activity of the Huaiyuan—Chihe fault is related to the neotec tonic environment in its surrounding area.The Tan-Lu fault zone is the largest seismogenic structure in this area and its activity has an important impact on other faults in the area.The latest activity of the Tan-Lu fault zone to the south of Mingguang fault zone occurred in Middle Pleistocene and thus the latest activity of the Huaiyuan—Chihe fault intersecting with the Tan-Lu fault zone also occurred in Middle Pleistocene.This may be the tectonic background in the Bengbu—Fengyang area where small and medium earthquakes dominated.

关 键 词：怀远—池河断裂 郯庐断裂南段 第四纪活动性 探槽 韭山 

分 类 号：P534.63[天文地球—第四纪地质学] P542[天文地球—古生物学与地层学]