郯庐断裂带赤山段全新世新活动的特征  

NEW ACTIVITY CHARACTERISTICS IN THE CHISHAN SECTION OF TAN-LU FAULT ZONE IN HOLOCENE

作　　者：郑海刚 姚大全[2] 赵朋[2] 杨源源[2] 黄金水[1,3] ZHENG Hai-gang;YAO Da-quan;ZHAO Peng;YANG Yuan-yuan;HUANG Jin-shui(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;Anhui Earthquake Agency,Hefei 230031,China;Mengcheng National Geophysical Observatory,University of Science and Technology of China,Mengcheng,Anhui 233500,China)

机构地区：[1]中国科学技术大学,地球和空间科学学院,合肥230026 [2]安徽省地震局,合肥230031 [3]安徽蒙城地球物理国家野外科学观测研究站,蒙城233500

出　　处：《地震地质》2023年第1期127-138,共12页Seismology and Geology

基　　金：国家自然科学基金(41802224);中国地震局地震科技星火计划项目(XH23020YA);安徽蒙城地球物理国家野外观测站联合开放基金(MEMGO-202216,MENGO-202112)共同资助。

摘　　要：文中在野外开挖探槽及年龄样品测试的基础上,对郯庐断裂带赤山段全新世的新活动特征进行了详细讨论。在泗县赤山镇徐井村附近开挖了2个地质探槽(XJ1、XJ2),其中XJ1探槽揭露了10个地层单元,从老到新依次为U_(1)—U_(10);发现3条断层,由东向西依次为F_(1)、F_(2)和F_(3);识别出3次古地震事件,由老到新依次为E_(1)、E_(2)和E_(3)。事件E_(1)和E_(2)分别为F_(1)和F_(2)的逆冲活动,事件E_(3)为F_(2)逆走滑和F_(3)正走滑共同活动的结果。前2次古地震事件E_(1)、E_(2)发生于中更新世—晚更新世晚期之间,后一次事件E_(3)代表最新一次古地震活动,发生于地层U9沉积以后,在该层上部采集的泥炭样品的测定年代为11.10~10.75ka BP,说明郯庐断裂带赤山段在全新世早期以后仍有活动。The Chishan section of Tan-Lu fault zone is located in Sixian County,northern Anhui Province.Research on the characteristics of Quaternary fault activity of this section began in the 1990s,which includes microgeomorphology survey,trench excavation,dating sample collection and measurement,and so on.Through these studies,many valuable data and results were accumulated,which laid a good foundation for the current research.Based on the field geological survey and previous studies,two geological trenches were excavated,which are named trench XJ1 and XJ2 respectively.Among them,very rich remains of ancient earthquakes were found in trench XJ1 and analyzed as major contents in this paper,and few relics of ancient earthquake were found in trench XJ2,which are not involved in this paper.In the trench XJ1,ten strata units were revealed,labeled as U_(1)to U_(10)from old to young,respectively.Layer U_(1)is the Cretaceous sandstone with a thickness about 0.5~1.0m,lying on the bottom of the west wall of the trench.Layer U2is yellowish brown clay with a thickness of 1~2.5m,located at the bottom of the eastern side of trench profile.One OSL sample is collected in the middle of this layer with an age more than 150ka BP,which indicates the layer was deposited before the Mid Pleistocene.Layer U3is purple clay-sand,which is wide at the bottom around 6.5m and narrow at the top around 2.5m,and the top extends about 7m continuously from west to east.Layer U4is motley gravel with a thickness about 2.0~2.5m,which is below layer U9and above layer U4on the west side of the trench wall.Layer U5is gravel containing a lot of clay and a few of sandstone clumps,wide at the top about 3m and narrow at the bottom about 2m.Layer U6is light green gravel containing some sand and clay,thick in the west about 0.8m and thin in the east about 0.2m,extending around 7m discontinuously from west to east.Layer U7is grayish white gravel with sand and clay,thick in the west around 1.0m and thin in the east around 0.2m,extending about 5m continuously from west

关 键 词：全新世 郯庐断裂带 逆断层陡坎 古地震 

分 类 号：P315.2[天文地球—地震学]