华南沿海广从断裂带北段断层泥中石英微形貌与第四纪活动性特征  

Microfeature of Quartz Collected from Fault Gouges in the North Section of the Guangzhou-Conghua Fault Zone Along Coastal South China and Fault Activity During Quaternary

作　　者：丁盛昌 邱世藩 朱照宇[1,2,3] 詹松 张秉良[7] DING Shengchang;QIU Shifan;ZHU Zhaoyu;ZHAN Song;ZHANG Bingliang(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Key Laboratory of Ocean and Marginal Sea Geology,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Center for Excellence in Deep Earth Science,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;School of Geography and Environmental Engineering,Gannan Normal University,Ganzhou 341000,Jiangxi,China;Guangdong Highway Design Institute,Guangzhou 510507,Guangdong,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院广州地球化学研究所边缘海与大洋地质重点实验室,广东广州510640 [3]中国科学院深地科学卓越创新中心,广东广州510640 [4]中国科学院大学地球与行星科学学院,北京100049 [5]赣南师范大学地理与环境工程学院,江西赣州341000 [6]广东省公路勘察规划设计院,广东广州510507 [7]中国地震局地质研究所,北京100029

出　　处：《大地构造与成矿学》2023年第2期327-336,共10页Geotectonica et Metallogenia

基　　金：广东省科技计划与广东省公路勘察规划设计院联合科技项目(KJXM-018);国家自然科学基金项目(40930106、41172320);中国地质调查局项目(1212011120118)联合资助。

摘　　要：对广东省中南部广(州)-从(化)活动断裂带北段断层泥中的石英碎粒进行了扫描电子显微镜(SEM)微形貌分析和电子自旋共振法(ESR)测年。研究结果显示,石英微形貌特征在断裂活动的刻蚀阶段主要表现为放射状、阶步状断口以及平直擦痕,在后期溶蚀阶段以Ⅰ_(A)类和Ⅰ_(B)类特征为主兼有Ⅰ_(C)类和Ⅱ-Ⅲ类形迹;石英ESR年龄为234~296 ka BP。据此分析,该研究地段的广从断裂带在第四纪至少有4次活动,其主要活动期在中更新世中晚期至晚更新世早期,在上新世也有轻微活动;断裂运动性质以快速滑动的粘滑为主,兼有缓慢运动的蠕滑;力学性质为压剪性和张剪性并存。尽管这些特征显示该地段广从断裂带在全新世活动性较弱,但断裂带造成的岩石破碎性和地形反差致使工程建筑的地基非常脆弱。因此,对该地段流溪河特大桥及周边地段应切实加强潜在地质灾害的监测和防治。We performed microstructure analysis with a scanning electronic microscope(SEM)and electron spin resonance(ESR)dating on detrital quartz grains collected from fault gouges in the north section of the Guangzhou-Conghua active fault zone in the mid-south of Guangdong province.Our results indicate that the microfeature of detrital quartz grains is primarily characterized by radial and step-like fractures with straight scratches formed during the scrape period of faulting,and Ⅰ_(A) and Ⅰ_(B)(combined with Ⅰ_(C),Ⅱ and Ⅲ)traces in the subsequent dissolution period.The ESR dating yielded ages of 234–296 ka BP.On the basis of these results,we suggest that the studied section of the Guangzhou-Conghua fault experienced at least four movements during the Quaternary,partly in the Pliocene.The main activity stage occurred in the period of the mid-late stage of the Mid-Pleistocene to the early stage of the Late Pleistocene,and the faulting movement was stick slip primarily characterized by rapid slip combined with creep slip of slow movement.The mechanical properties are both compressional and tensile shearings.Although these features indicate that the movement of this section of the Guangzhou-Conghua fault zone was less active in the Holocene,significant rock disintegration and landform contrast resulted from the faulting make the foundation of architectural engineering very fragile.Consequently,the monitoring and prevention of potential geological hazards should be strengthened for the Liuxi River super-large bridge and its surrounding areas.

关 键 词：断层泥 石英微形貌 ESR测年 第四纪活动性 广从断裂带 华南沿海 

分 类 号：P542[天文地球—构造地质学] P572[天文地球—地质学]