论文部分内容阅读
安丘-莒县断裂(F_5)为郯庐断裂带中段东地堑内最新活动断裂。近年来,F_5江苏段研究成果丰硕,发现不同地段普遍存在全新世活动性,运动方式以右旋走滑兼挤压逆冲为主。以往研究未讨论过F_5在淮河以南安徽境内的延伸情况以及进一步的活动性问题。文中选取与F_5江苏段线性影像特征延伸一致的淮河南岸郯庐紫阳山段作为突破口,通过遥感影像解译、地质地貌调查和探槽开挖,初步得到以下认识:1)紫阳山段线性构造地貌特征清晰,断层发育于浮山至紫阳山一线的中生代红色砂岩隆起边缘缓坡,为安丘-莒县断裂(F_5)过淮河后的南延部分;2)朱刘探槽开挖揭示,该段错断了晚更新世晚期黏土层,晚更新世晚期—全新世早期黑色黏土层受断层活动影响沿断面灌入、填充,形成黑色断层条带及黑土充填楔,表明断层最新活动时代达全新世早期;3)朱刘探槽开挖揭示,该段第四纪以来存在至少3次古地震事件,第1次古地震事件推测年代为第四纪早、中期,第2次古地震事件年代为20.10~13.46ka BP,第3次古地震事件年代为(10.15±0.05)~(8.16±0.05)ka BP。上述研究成果弥补了对郯庐断裂带安徽段晚第四纪活动性认识的不足,为安徽省的地震监测和震害防御工作提供了基础数据。
Anqiu-Juxian fault (F_5) is the latest active fault in the eastern segment of the eastern segment of the Tanlu fault zone. In recent years, F_5 Jiangsu section has made fruitful research and found that Holocene mobility is commonly found in different locations. The mode of exercise is mainly dextral strike-slip and extrusion thrusting. Previous studies did not discuss the extension of F_5 in Anhui Province south of the Huaihe River and further activities. In this paper, the Ziyang section of Tanlu Lake on the south bank of the Huaihe River which is consistent with the extension of the linear image features of F_5 section in Jiangsu Province is taken as a breakthrough point. Through the interpretation of remote sensing images, the survey of geology and geomorphology and the excavation of trenches, the following understandings are obtained: 1) The fault is characterized by a gentle ramp with a gentle ramp on the uplift edge of the Mesozoic red sandstone from the Fushan to the Ziyangshan line, which is the southern extension of the Anqiu-Juxian fault (F_5) over the Huaihe River. 2) Excavation of the Zhu Liu trench reveals that this fault During Late Late Pleistocene, the black clay layer in the late Late Pleistocene-Early Holocene was flooded and filled along the fault plane due to the fault activity. The black fault zone and the black-field fill wedge were formed, indicating that the latest active stage of the fault reached the stage of Early Holocene ; 3) Excavation of Zhu Liu trenches reveals that there are at least three paleoseismic events since the Quaternary, the first paleoseismic event is estimated to be Quaternary in the early, mid and second paleo-seismic events ~ 13.46ka BP, and the age of the third paleoearthquake was (10.15 ± 0.05) ~ (8.16 ± 0.05) ka BP. The above research results make up for the lack of understanding of Late Quaternary activities in the Anhui section of the Tan-Lu fault zone, and provide the basic data for earthquake monitoring and earthquake damage prevention in Anhui Province.