金坛-如皋断裂北东段浅层地震勘探新证据  

NEW EVIDENCE ON NE-SEGMENT OF JINTAN-RUGAO FAULT DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD

作　　者：顾勤平[1,2] 杨浩[1] 赵启光[1] 孟科[1] 王金艳[1] 李云[3] 马董伟 GU Qin-ping;YANG Hao;ZHAO Qi-guang;MENG Ke;WANG Jin-yan;LI Yun;MA Dong-wei(Jiangsu Earthquake Agency,Nanjing 210014,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Nanjing Institute of Geology and Mineral Resources,Nanjing 210016,China;Shenfeng Institute of Geological Techniques Co.,Ltd,Shanghai 201107,China)

机构地区：[1]江苏省地震局,南京210014 [2]中国地震局地球物理研究所,北京100081 [3]南京地质矿产研究所,南京210016 [4]上海申丰地质新技术应用研究所有限公司,上海201107

出　　处：《地震地质》2019年第3期743-758,共16页Seismology and Geology

基　　金：中国地震重点监视防御区活动断层探测之栟茶河断裂活动性鉴定项目(1530601);国家自然科学基金(41704052);中国地震局地震科技星火计划项目(XY18017Y)共同资助

摘　　要：NE向的区域性深大断裂——金坛-如皋断裂为苏北坳陷区和南通隆起区的分界断裂。为了调查金坛-如皋断裂北东段的空间位置、性质和断裂构造特征并重新厘定其活动性,文中在石油地震勘探剖面提供的金坛-如皋断裂北东段大体空间位置及反射标志层的基础上,布设了4条浅层人工地震勘探剖面,对金坛-如皋断裂北东段进行了高分辨率地震反射成像,获得了测线控制范围内清晰的地下结构和断裂构造成像结果。结果表明,金坛-如皋断裂北东段并非单一的一条断层,而是由2条N倾、NEE走向的正断层组成的断裂带。浅层地震叠加剖面揭示活动性更强的南支上断点埋深235~243m,断错了下更新统底界,结合测线周边的钻孔资料推测其最新活动时代为第四纪早更新世(QP^1)。文中的研究结果为确定金坛-如皋断裂北东段的位置及其活动性评价提供了可靠的地震学资料。The NE-trending regional deep fault,i.e.the Jintan-Rugao Fault,is a boundary fault between the Subei depression and Nantong uplift,and its research has always received broad attention because of its importance and complexity.For the absence of definite proof,there is little consensus regarding the structure and spatial distribution of the fault among geoscientists,and its latest active time is ambiguous.The study of Quaternary activity characteristics of the Jintan-Rugao Fault is of great significance for earthquake trend prediction and engineering safety evaluation,and for earthquake prevention and disaster reduction in Jiangsu Province.In order to investigate the spatial location,characteristics and tectonic features and redefine the activity of the NE-segment of the Jintan-Rugao Fault,and on the basis of likely location and marker beds derived from petroleum seismic exploration sections,we collect and arrange 4 shallow seismic exploration profiles crossing the fault to conduct high-resolution seismic reflection imaging,following the working concept of ‘from known to unknown,from deep to shallow’.In this study,an observation system with trace intervals of 4~6m,shot intervals of 12~18m,and channels of 90~256 and 15~36 folds is used.In addition,by introducing different tonnage vibroseis to suppress the background noise,the raw data with high SNR(signal-noise ratio)can be obtained.By using the above working method and spread geometry,we obtained clear imaging results of the subsurface structure and fault structure in the coverage area of the survey lines.This exploration research accurately locates the NE-segment of Jintan-Rugao Fault,and further shows that it is not a single fault but a fault zone consisting of two normal faults with N-dipping and NE-striking within the effective detection depth.The shallow seismic profiles reveal that the up-breakpoint on the south branch with stronger activity is at depth of 235~243m,which offsets the lower strata of lower Pleistocene.Combining drilling data around the surv

关 键 词：金坛-如皋断裂 北东段 浅层地震勘探 第四纪活动 

分 类 号：P642.27[天文地球—工程地质学]