郯庐断裂带安徽明光段紫阳山探槽及其意义

The Ziyang Hill Trenches in the Anhui Mingguang Section of the Tan-Lu Fault Zone and Their Significance

郯庐断裂带安徽省内段落属于该断裂带的南段,断裂构造复杂,总体上断层活动性要弱于断裂带的山东、江苏段。近年来笔者多次在苏皖交界地区开展野外地质地貌调查,发现淮河南北两侧的地形地貌存在较大差异。本研究以淮河以南的郯庐断裂带东支断裂明光段为探查重点,在明光紫阳山北侧跨断层开挖地质探槽。探槽(Tc1)显示断层表现为逆冲、张裂等活动形式,且断层向上延伸错动晚第四纪地层;结合年代样品测试结果,表明该段断层晚第四纪以来有较强的活动,最新活动时代可达晚更新世-全新世早期;探槽揭露的断层表现出多种活动形式,显示了明光段断层活动的多期次性和区域构造应力场的复杂性。

The faults in the Anhui section of the Tan-Lu fault zone belong to the southern part of the faults zone. The fault structure is complex. On the whole, the fault activity is weaker than that of the Shandong and Jiangsu segment. In recent years, the author has carried out geological survey in the border area of Jiangsu and Anhui Provinces, and found that there are great differences in the topography of the Huaihe River on both sides. This work focuses on the east segment of the Tan-Lu fault zone in the south of Huaihe. We have dug two geological trenches, crossing the faults on the north side of the Ziyang hill. Trench Tc1 shows that there are two active forms of the faults, thrust and extension. The faults extend into the Quaternary strata. Based on strata ages, the results show that there is a strong activity in the late Quaternary period, and the newest age of activity is the late Pleistocene to early Holocene. The trenchs show that the faults have a variety of motion characteristics,which show the multiple phases of fault activity and the complexity of regional tectonic stress field.