郯庐断裂带安徽紫阳山段发现全新世活动证据

发布时间：2018-10-26 15:46

【摘要】：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。
[Abstract]:Anqiu-Juxian fault (FShi5) is the latest active fault in the eastern graben in the middle part of the Tanlu fault zone. In recent years, the study of F5 Jiangsu section has been fruitful, and it has been found that Holocene activity exists generally in different areas, and the movement mode is mainly dextral strike-slip and compression-thrust. Previous studies have not discussed the extension and further activity of FS5 in Anhui Province south of the Huaihe River. In this paper, the Tan-Lu Ziyang Mountain section along the southern bank of the Huaihe River, which is consistent with the linear image features of the FSP 5 Jiangsu section, is selected as the breakthrough point. Through remote sensing image interpretation, geological and geomorphological investigation and trench excavation, The main conclusions are as follows: 1) the linear structural and geomorphologic features of Ziyang Mountain segment are clear, and the fault developed in the marginal gentle slope of Mesozoic red sandstone uplift from Fushan to Ziyangshan, which is the southern extension of the Anqiu-Juxian fault (F5) after the Huaihe River; 2) the excavation of Zhu Liu grooves reveals that the late Pleistocene clay layer was staggered, and the black clay layer was filled with black fault belt and black soil filling wedge along the cross section under the influence of fault activity in late Pleistocene and early Holocene. It indicates that the latest active age of fault reaches the early Holocene. 3) the excavation of Zhu Liu trench reveals that there are at least three paleoearthquakes since Quaternary, the first paleoearthquake event is early Quaternary, the middle period is Quaternary, and the second paleoearthquake event is 20.10~13.46ka BP,. The age of the third paleoearthquake event was (10.15 卤0. 05) ~ (8. 16 卤0. 05) ka BP.). The above research results make up for the deficiency of understanding the late Quaternary activity in Anhui section of the Tanlu fault zone and provide basic data for earthquake monitoring and earthquake disaster prevention in Anhui Province.
【作者单位】：安徽省地震局;
【基金】：中国地震局项目“郯庐断裂带三维地震构造分段模型与地震预测研究专项”(TYZ20160101) 安徽省公益性地质项目(2015-g-25) 地震科技星火计划青年项目(XH16018Y)共同资助
【分类号】：P315.2

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