长垣断陷的地壳浅部结构和构造——地震反射剖面结果
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摘要
为研究长垣断陷的地壳浅部结构和断裂浅部构造特征,跨长垣断陷完成了一条长度49km的中深层地震反射剖面和一条长度7km的浅层地震反射剖面。根据获得的地震反射剖面,结合区域地质资料,分析研究区的地壳浅部结构和断裂活动特征。结果表明,长垣断陷是一个东深、西浅的箕状断陷;黄河断裂为西倾的铲形正断层,其浅部错断了埋深约190m的第四纪地层,其下部错断了多组反射地层和盆地基底,属第四纪以来的隐伏活动断裂;长垣断裂浅部错断了新近纪地层的底界,向下延伸至基底之下,属前第四纪断裂。本文研究成果为新乡市及其邻区的活动构造研究和地震危险性评价提供了地震学证据。
In order to investigate crustal shallow structures and fault shallow tectonic features crossing the Changyuan fault depression,we completed a 49 km multiple shallow seismic reflection profile and a 7 km shallow seismic reflection profile.According to the seismic reflection profiles and combined with the regional geological data,we analyze the crustal shallow structures and the fault shallow tectonic features in the study area.The results show that Changyuan fault depression is a deep east and shallow west dustpan-like subsidence,and the Cenozoic basement of the fault depression plunges from west to east;Huanghe fault is the west dipping spade shaped normal fault,and this fault disrupts190 m Quaternary strata in the shallow part,disrupting multi-group Cenozoic lays and the crystalline basement.Therefore,it is a buried active fault in the Quaternary period;Changyuan fault disrupts the bottom of Neogene strata in shallow part,and it extends below the crystalline basement,therefore it is a Pre-Quaternary fault.The result provides seismological evidence for active tectonic research and seismic risk evaluation in Xinxiang and its neighboring districts.
In order to investigate crustal shallow structures and fault shallow tectonic features crossing the Changyuan fault depression,we completed a 49 km multiple shallow seismic reflection profile and a 7 km shallow seismic reflection profile.According to the seismic reflection profiles and combined with the regional geological data,we analyze the crustal shallow structures and the fault shallow tectonic features in the study area.The results show that Changyuan fault depression is a deep east and shallow west dustpan-like subsidence,and the Cenozoic basement of the fault depression plunges from west to east;Huanghe fault is the west dipping spade shaped normal fault,and this fault disrupts190 m Quaternary strata in the shallow part,disrupting multi-group Cenozoic lays and the crystalline basement.Therefore,it is a buried active fault in the Quaternary period;Changyuan fault disrupts the bottom of Neogene strata in shallow part,and it extends below the crystalline basement,therefore it is a Pre-Quaternary fault.The result provides seismological evidence for active tectonic research and seismic risk evaluation in Xinxiang and its neighboring districts.
引文
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[2]徐锡伟.活动断层、地震灾害与减灾对策问题[J].震灾防御技术,2006,1(1):7-14(Xu Xiwei.Active Faults,Associated Earthquake Disaster Distribution and Policy for Disaster Reduction[J].Technology for Earthquake Disaster Prevention,2006,1(1):7-14)
[3]徐锡伟,闻学泽,叶建青,等.汶川MS8.0地震地表破裂带及其发震构造[J].地震地质,2008,30(3):597-629(Xu Xiwei,Wen Xueze,Ye Jianqing,et al.The MS8.0 Wenchuan Earthquake Surface Ruptures and Its Seismogenic Structure[J].Seismology and Geology,2008,30(3):597-629)
[4]何政勤,陈宇坤,叶太兰,等.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,2007,29(2):363-371(He Zhengqin,Chen Yukun,Ye Tailan,et al.Application of Shallow Seismic Exploration in Detection of Buried Fault in Coastal Areas[J].Seismology and Geology,2007,29(2):363-371)
[5]刘保金,柴炽章,酆少英,等.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,2008,51(5):1 475-1 483(Liu Baojin,Chai Chizhang,Feng Shaoying,et a1.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,2008,51(5):1 475-1 483)
[6]刘保金,胡平,陈颙,等.北京平原西北部地壳浅部结构和隐伏活动断裂——由地震反射剖面揭示[J].地球物理学报,2009,52(8):2 015-2 025(Liu Baojin,Hu Ping,Chen Yong,et al.the Crustal Sha1low Structures and Buried Active Fau1ts Revea1ed by Seismic Reflection Profiles in Northwestern Area of Being P1ain[J].Chinese Journal of Geophysics,2009,52(8):2 015-2 025)
[7]李令喜.东濮凹陷河岸地区构造演化与油气聚集规律研究[D].北京:中国地质大学,2006(Li Lingxi.Study of Tectonic Evolution and Rule of Oil-Gas Accumulation in He’an Area in the Dongpu Depression[D].Beijing:China University of Geosciences,2006)
[8]刘秋生.再谈东濮凹陷断层解释[J].石油地球物理勘探,1990,25(6):700-711(Liu Qiusheng.A Further Exposition of Fault Interpretation in Dongpu Depression[J].Oil Geophysical Prospecting,1990,25(6):700-711)
[9]任文菊,刘明清,赵丽.豫北深、浅部构造特征与地震[J].华北地震科学,2000,18(3):9-16(Ren Wenju,Liu Mingqing,Zhao Li.Deep and Shallow Tectonic Features and Earthquakes in North Henan[J].North China Earthquake Sciences,2000,18(3):9-16)
[10]魏雄辉.东濮凹陷马厂地区变换带和断裂体系研究[M].北京:中国地质大学,2009(Wei Xionghui.Analysis of Transition Zone and Faulting System in Machang Region of Dongpu Depression[M].Beijing:China University of Geosciences,2009)
[11]张克鑫,漆家福,赵衍彬,等.新生代东濮凹陷构造特征及其演化[J].新疆石油地质,2007,28(6):714-717(Zhang Kexin,Qi Jiafu,Zhao Yanbin,et al.Structure and Evolution of Cenozoic in Dongpu Sag[J].Xinjiang Petroleum Geology,2007,28(6):714-717)