金坛-如皋断裂北东段浅层地震勘探新证据
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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(Q1P)。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 ～ 6 m,shot intervals of 12 ～ 18 m,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 NEstriking 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 ～ 243 m,which offsets the lower strata of lower Pleistocene. Combining drilling data around the survey lines,we infer the activity time of this fault is early Pleistocene. The results of this paper provide reliable seismological data for determining the location and activity evaluation of the NE-segment of Jintan-Rugao Fault. In eastern China,where the sedimentary layer is thicker,the latest active age of faults can not be determined entirely according to the latest faulted strata. For a fault passing through the thicker area of new deposits,its latest active age should be based on the tectonic background,seismic activity,present tectonic stress field, topographic deformation, structural micro-geomorphological characteristics, sedimentary thickness of new strata,controlling effect of faults on new strata and the latest strata of faults,and combined with upper breakpoints,morphology,structure and occurrence of faults,the active state of the target concealed faults should be analyzed. If the activity of the fault is judged only by the upper faulted point,it may lead to overestimating the age of the fault activity.
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 ～ 6 m,shot intervals of 12 ～ 18 m,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 NEstriking 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 ～ 243 m,which offsets the lower strata of lower Pleistocene. Combining drilling data around the survey lines,we infer the activity time of this fault is early Pleistocene. The results of this paper provide reliable seismological data for determining the location and activity evaluation of the NE-segment of Jintan-Rugao Fault. In eastern China,where the sedimentary layer is thicker,the latest active age of faults can not be determined entirely according to the latest faulted strata. For a fault passing through the thicker area of new deposits,its latest active age should be based on the tectonic background,seismic activity,present tectonic stress field, topographic deformation, structural micro-geomorphological characteristics, sedimentary thickness of new strata,controlling effect of faults on new strata and the latest strata of faults,and combined with upper breakpoints,morphology,structure and occurrence of faults,the active state of the target concealed faults should be analyzed. If the activity of the fault is judged only by the upper faulted point,it may lead to overestimating the age of the fault activity.
引文
柴炽章,孟广魁,杜鹏,等.2006.隐伏活动断层的多层次综合探测:以银川隐伏活动断层为例[J].地震地质,28(4):536-546.CHAI Chi-zhang,MENG Guang-kui,DU Peng,et al.2006.Comprehensive multi-level exploration of buried active fault:An example of Yinchuan buried active fault[J].Seismology and Geology,28(4):536-546(in Chinese).
陈书平,王小群,王章青,等.2009.海安凹陷上白垩统-新生界断裂形成及演化[J].石油地球物理勘探,44(6):760-766.CHEN Shu-ping,WANG Xiao-qun,WANG Zhang-qing,et al.2009.The fracture formation and its evolution from Upper Cretaceous to Cenozoic in Hai'an Depression[J].Geophysical Prospcting for Petropleum,44(6):760-766(in Chinese).
邓起东,卢造勋,杨主恩.2007.城市活断层探测和断层活动性评价问题[J].地震地质,29(2):189-200.DENG Qi-dong,LU Zao-xun,YANG Zhu-en.2007.Remarks on urban active faults exploration and associated activity assessment[J].Seismology and Geology,29(2):189-200(in Chinese).
方盛明,张先康,刘保金,等.2002.大城市活断层探测的地球物理方法[J].地震地质,24(4):606-613.FANG Sheng-ming,ZHANG Xian-kang,LIU Bao-jin,et al.2002.Geophysical methods of the exploration of active faults in urban areas[J].Seismology and Geology,24(4):606-613(in Chinese).
顾勤平,康清清,许汉刚,等.2013.薄覆盖层地区隐伏断层及其上断点探测的地震方法技术:以废黄河断层为例[J].地球物理学报,56(5):1609-1618.GU Qin-ping,KANG Qing-qing,XU Han-gang,et al.2013.Seismic exploration methods for buried faults and its upbreakpoint in thin sediment areas:An example of the Feihuanghe Fault[J].Chinese Journal of Geophysics,56(5):1609-1618(in Chinese).
顾勤平,许汉刚,赵启光.2015.厚覆盖层地区隐伏活断层探测的地震方法技术:以桥北镇-宿迁断层为例[J].物探与化探,39(2):408-415.GU Qin-ping,XU Han-gang,ZHAO Qi-guang.2015.The seismic exploration method for buried active fault in thick sediment area:A case study of Qiaobei-Suqian Fault[J].Geophysical and Geochemical Exploration,39(2):408-415(in Chinese).
何正勤,陈宇坤,叶太兰,等.2007.浅层地震勘探在沿海地区隐伏断层探测中的应用[J].地震地质,29(2):363-371.HE Zheng-qin,CHEN Yu-kun,YE Tai-lan,et al.2007.Application of shallow seismic exploration in detection of buried fault in coastal areas[J].Seismology and Geology,29(2):363-371(in Chinese).
何正勤,潘华,胡刚,等.2010.核电厂址隐伏断裂探测中的地震勘探方法研究[J].地球物理学报,53(2):326-334.HE Zheng-qin,PAN Hua,HU Gang,et al.2010.Study on the seismic exploration method to detect buried fault in the site of nuclear power plant[J].Chinese Journal of Geophysics,53(2):326-334(in Chinese).
刘保金,柴炽章,酆少英,等.2008.第四纪沉积区断层及其上断点探测的地震方法技术:以银川隐伏活动断层为例[J].地球物理学报,51(5):1475-1483.LIU Bao-jin,CHAI Chi-zhang,FENG Shao-ying,et al.2008.Seismic exploration method for buried fault and its up breakpoint in Quaternary sediment area:An example of Yinchuan buried active fault[J].Chinese Journal of Geophysics,51(5):1475-1483(in Chinese).
邱海峻,许志琴,乔德武.2006.苏北盆地构造演化研究进展[J].地质通报,25(9-10):1117-1120.QIU Hai-jun,XU Zhi-qin,QIAO De-wu.2006.Progress in the study of the tectonic evolution of the Subei Basin,Jiangsu,China[J].Geological Bulletin of China,25(9-10):1117-1120(in Chinese).
冉怀江,司宝玲,陈方鸿,等.2012.海安凹陷古近系沉积层序及对油气藏的控制[J].石油地球物理勘探,47(5):795-802.RAN Huai-jiang,SI Bao-ling,CHEN Fang-hong,et al.2012.Sedimentary sequences in Hai'an Depression and control on reservoir of the Paleocene[J].Oil Geophysical Prospecting,47(5):795-802(in Chinese).
伊尔马滋O.1994.地震数据处理[M].黄续德,袁明德译.北京:石油工业出版社:1-80.YILMAZ O.1994.Seismic Data Processing[M].Translated by HUANG Xu-de,YUAN Ming-de.Petroleum Industry Press,Beijing:1-80(in Chinese).
许汉刚,范小平,冉勇康,等.2016.郯庐断裂带宿迁段F5断裂浅层地震勘探新证据[J].地震地质,38(1):31-43.doi:10.3969/j.issn.0253-4967.2016.01.003.XU Han-gang,FAN Xiao-ping,RAN Yong-kang,et al.2016.New evidence of the Holocene fault in Suqian segment of the Tanlu fault zone discovered by shallow seismic exploration method[J].Seismology and Geology,38(1):31-43(in Chinese).
中国地震局.2005.活断层探测方法[M].北京:地震出版社:1-2.China Earthquake Administration.2005.Method for Surveying and Prospecting of Active Fault[M].Seismological Press,Beijing:1-2(in Chinese).
左丽琼,王彩会,荆慧,等.2016.综合物探方法在南通小洋口地区地热勘查中的应用[J].工程地球物理学报,13(1):122-129.ZUO Li-qiong,WANG Cai-hui,JING Hui,et al.2016.The application of comprehensive geophysical prospecting method to geothermal prospecting in Xiaoyangkou of Nantong City in Jiangsu[J].Chinese Journal of Engineering Geophysics,13(1):122-129(in Chinese).
(1)张永鸿,1985,下扬子含油气区构造区划与含油气远景研究。
(2)王明义,1991,江苏省苏中工区1︰5万重力测量成果报告。
(3)张登明,2003,1︰25万南通市幅区域地质调查报告。
(1)江仁庆,1982,苏北黄桥地区地震普查成果报告。
(1)张登明,2003,1︰25万南通市幅区域地质调查报告。
(2)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。
(1)高中和,2001,南黄海地震区划研究报告。
(1)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。
(2)张登明,2003,1︰25万南通市幅区域地质调查报告。
(1)张登明,2003,1︰25万南通市幅区域地质调查报告。
(2)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。
陈书平,王小群,王章青,等.2009.海安凹陷上白垩统-新生界断裂形成及演化[J].石油地球物理勘探,44(6):760-766.CHEN Shu-ping,WANG Xiao-qun,WANG Zhang-qing,et al.2009.The fracture formation and its evolution from Upper Cretaceous to Cenozoic in Hai'an Depression[J].Geophysical Prospcting for Petropleum,44(6):760-766(in Chinese).
邓起东,卢造勋,杨主恩.2007.城市活断层探测和断层活动性评价问题[J].地震地质,29(2):189-200.DENG Qi-dong,LU Zao-xun,YANG Zhu-en.2007.Remarks on urban active faults exploration and associated activity assessment[J].Seismology and Geology,29(2):189-200(in Chinese).
方盛明,张先康,刘保金,等.2002.大城市活断层探测的地球物理方法[J].地震地质,24(4):606-613.FANG Sheng-ming,ZHANG Xian-kang,LIU Bao-jin,et al.2002.Geophysical methods of the exploration of active faults in urban areas[J].Seismology and Geology,24(4):606-613(in Chinese).
顾勤平,康清清,许汉刚,等.2013.薄覆盖层地区隐伏断层及其上断点探测的地震方法技术:以废黄河断层为例[J].地球物理学报,56(5):1609-1618.GU Qin-ping,KANG Qing-qing,XU Han-gang,et al.2013.Seismic exploration methods for buried faults and its upbreakpoint in thin sediment areas:An example of the Feihuanghe Fault[J].Chinese Journal of Geophysics,56(5):1609-1618(in Chinese).
顾勤平,许汉刚,赵启光.2015.厚覆盖层地区隐伏活断层探测的地震方法技术:以桥北镇-宿迁断层为例[J].物探与化探,39(2):408-415.GU Qin-ping,XU Han-gang,ZHAO Qi-guang.2015.The seismic exploration method for buried active fault in thick sediment area:A case study of Qiaobei-Suqian Fault[J].Geophysical and Geochemical Exploration,39(2):408-415(in Chinese).
何正勤,陈宇坤,叶太兰,等.2007.浅层地震勘探在沿海地区隐伏断层探测中的应用[J].地震地质,29(2):363-371.HE Zheng-qin,CHEN Yu-kun,YE Tai-lan,et al.2007.Application of shallow seismic exploration in detection of buried fault in coastal areas[J].Seismology and Geology,29(2):363-371(in Chinese).
何正勤,潘华,胡刚,等.2010.核电厂址隐伏断裂探测中的地震勘探方法研究[J].地球物理学报,53(2):326-334.HE Zheng-qin,PAN Hua,HU Gang,et al.2010.Study on the seismic exploration method to detect buried fault in the site of nuclear power plant[J].Chinese Journal of Geophysics,53(2):326-334(in Chinese).
刘保金,柴炽章,酆少英,等.2008.第四纪沉积区断层及其上断点探测的地震方法技术:以银川隐伏活动断层为例[J].地球物理学报,51(5):1475-1483.LIU Bao-jin,CHAI Chi-zhang,FENG Shao-ying,et al.2008.Seismic exploration method for buried fault and its up breakpoint in Quaternary sediment area:An example of Yinchuan buried active fault[J].Chinese Journal of Geophysics,51(5):1475-1483(in Chinese).
邱海峻,许志琴,乔德武.2006.苏北盆地构造演化研究进展[J].地质通报,25(9-10):1117-1120.QIU Hai-jun,XU Zhi-qin,QIAO De-wu.2006.Progress in the study of the tectonic evolution of the Subei Basin,Jiangsu,China[J].Geological Bulletin of China,25(9-10):1117-1120(in Chinese).
冉怀江,司宝玲,陈方鸿,等.2012.海安凹陷古近系沉积层序及对油气藏的控制[J].石油地球物理勘探,47(5):795-802.RAN Huai-jiang,SI Bao-ling,CHEN Fang-hong,et al.2012.Sedimentary sequences in Hai'an Depression and control on reservoir of the Paleocene[J].Oil Geophysical Prospecting,47(5):795-802(in Chinese).
伊尔马滋O.1994.地震数据处理[M].黄续德,袁明德译.北京:石油工业出版社:1-80.YILMAZ O.1994.Seismic Data Processing[M].Translated by HUANG Xu-de,YUAN Ming-de.Petroleum Industry Press,Beijing:1-80(in Chinese).
许汉刚,范小平,冉勇康,等.2016.郯庐断裂带宿迁段F5断裂浅层地震勘探新证据[J].地震地质,38(1):31-43.doi:10.3969/j.issn.0253-4967.2016.01.003.XU Han-gang,FAN Xiao-ping,RAN Yong-kang,et al.2016.New evidence of the Holocene fault in Suqian segment of the Tanlu fault zone discovered by shallow seismic exploration method[J].Seismology and Geology,38(1):31-43(in Chinese).
中国地震局.2005.活断层探测方法[M].北京:地震出版社:1-2.China Earthquake Administration.2005.Method for Surveying and Prospecting of Active Fault[M].Seismological Press,Beijing:1-2(in Chinese).
左丽琼,王彩会,荆慧,等.2016.综合物探方法在南通小洋口地区地热勘查中的应用[J].工程地球物理学报,13(1):122-129.ZUO Li-qiong,WANG Cai-hui,JING Hui,et al.2016.The application of comprehensive geophysical prospecting method to geothermal prospecting in Xiaoyangkou of Nantong City in Jiangsu[J].Chinese Journal of Engineering Geophysics,13(1):122-129(in Chinese).
(1)张永鸿,1985,下扬子含油气区构造区划与含油气远景研究。
(2)王明义,1991,江苏省苏中工区1︰5万重力测量成果报告。
(3)张登明,2003,1︰25万南通市幅区域地质调查报告。
(1)江仁庆,1982,苏北黄桥地区地震普查成果报告。
(1)张登明,2003,1︰25万南通市幅区域地质调查报告。
(2)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。
(1)高中和,2001,南黄海地震区划研究报告。
(1)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。
(2)张登明,2003,1︰25万南通市幅区域地质调查报告。
(1)张登明,2003,1︰25万南通市幅区域地质调查报告。
(2)刘宪光,2016,江苏省1︰5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。