泉州盆地及其邻区地壳深部结构的探测与研究
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摘要
泉州盆地及其邻区地处我国大陆东南沿海地震带北段。通过对泉州盆地进行深地震反射探测,获得了该地区近地表至Moho面的精细几何结构及其深浅构造关系图像。这是该区第一条深地震反射探测剖面。分析结果表明,泉州盆地及其邻区地壳厚度变化在29.5~31.0km,由上地壳和下地壳组成。上地壳和下地壳又可以各分为2层。泉州盆地及其邻区近地表至浅部断裂发育,这些断裂向地壳深部最大延伸深度为6~12km,断裂的倾角随深度增加而逐渐变小,呈铲形正断层终止于上地壳上部反射界面C1以上。在永安-晋江断裂带之下的上地壳下部和下地壳中,存在着切割上、下地壳分界面和Moho面的高倾角深断裂,尽管深浅部断裂构造不相连接,但由于深部存在深断裂,具有发生中强以上地震的深部构造环境。这一深地震反射探测成果的获得,使得泉州盆地及其邻区深部资料解释的可靠性和探测精度比以往显著提高;深浅部构造组合取得了统一的解释结果;地壳的分层和结构特征更为确切和精细;首次发现了上地壳的拉张性构造及铲式正断层组合特征。不仅有助于泉州及其邻区地震危险性的综合判定,而且对深化东南沿海地震带及台湾海峡深部动力学过程的认识具有重要意义。
The Quanzhou basin and its adjacent area locate in the middle of the southeastern coast seismic belt on the Chinese mainland. The very fine geometry structure of this area from near ground to Moho interface and the relationship between the deep and shallow faults are obtained based on deep seismic reflection profiling. This profile is the first deep seismic reflection profile in this area and it indicates that the crust can be divided into the upper crust and the lower crust and the thickness of crust is from 29.5km to 31km in this area. The upper crust and the lower crust can be also divided to two layers. There are shallow normal faults developed in the upper crust and extending to the depth from 6km to 12km. The angle of those listric faults decreases with the depth and the faults joint into the C_1 interface (detachment surface). There is a high angle fault under the Yong'an-Jinjiang fault belt which cuts off the interface of the upper crust and the lower crust and the Moho interface. Although there is no connection between the shallow and the deep faults,it offers deep structural environment for moderate and strong earthquake because of the deep high angle fault. This exploration result improves the reliability and precision of explanation of deep crustal structure in this area. The pull-apart and listric normal fault model indicates that the upper crust structure accords to the dynamic process of Taiwan Strait. This is helpful for seismicity estimation of Quanzhou and its adjacent area and important for obtaining more of the dynamic process of the southeastern coast seismic belt.
The Quanzhou basin and its adjacent area locate in the middle of the southeastern coast seismic belt on the Chinese mainland. The very fine geometry structure of this area from near ground to Moho interface and the relationship between the deep and shallow faults are obtained based on deep seismic reflection profiling. This profile is the first deep seismic reflection profile in this area and it indicates that the crust can be divided into the upper crust and the lower crust and the thickness of crust is from 29.5km to 31km in this area. The upper crust and the lower crust can be also divided to two layers. There are shallow normal faults developed in the upper crust and extending to the depth from 6km to 12km. The angle of those listric faults decreases with the depth and the faults joint into the C_1 interface (detachment surface). There is a high angle fault under the Yong'an-Jinjiang fault belt which cuts off the interface of the upper crust and the lower crust and the Moho interface. Although there is no connection between the shallow and the deep faults,it offers deep structural environment for moderate and strong earthquake because of the deep high angle fault. This exploration result improves the reliability and precision of explanation of deep crustal structure in this area. The pull-apart and listric normal fault model indicates that the upper crust structure accords to the dynamic process of Taiwan Strait. This is helpful for seismicity estimation of Quanzhou and its adjacent area and important for obtaining more of the dynamic process of the southeastern coast seismic belt.
引文
福建省地质矿产局,1985,福建省区域地质志,北京:地质出版社,1～671。
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廖其林、王振明、邱陶兴等,1990,福州盆地及其周围地区地壳深部结构与构造的初步研究,地球物理学报,33(2):163～173。
马杏垣,1989,中国岩石圈动力学图集,北京:中国地图出版社,1～68。
徐锡伟、吴卫民、张先康等,2002,首都圈地区地壳最新构造变动与地震,北京:科学出版社,1～376。
朱金芳、徐锡伟、黄宗林等,2005a,福州市活断层探测与地震危险性评价,北京:科学出版社。
朱金芳、徐锡伟、张先康等,2005b,福州盆地及邻区地壳精细结构的深地震反射与高分辨率折射及宽角反射/折射联合探测研究,中国科学D辑,35(8):738～749。
张友南、孙君秀,1999,华北北部克拉通地壳岩石的波速特征与地壳物质组成,地震地质,21(2):147～155。
Fountain D M,Arculus R,Kay R W.,1992,Continental Lower Crust,Amsterdam:Elsevier,1～485.
Hole,J.A.,1992,Nonlinear high-resolutionthree-dimensional seismic travel time tomography,J.Geophys.Res.,97,6553～6562.
Rutter E H,et al.,1999,Synthetic seismic reflection profile through the Ivrea zone-Serie dei Laghi continental crustal section,northernwestern Italy,Geology,27(1):79～82.
ZhuJinfang,Huang Zonglin,Xu Xiwei,2005,Active Faults Exploration and Seismic Hazard Assessment in Fuzhou City,Earthquake Reserchin China,19(3):224～239.
廖其林、王振明、王屏路等,1988,福州—泉州—汕头地区地壳结构的爆炸地震研究,地球物理学报,31(3):270～280。
廖其林、王振明、邱陶兴等,1990,福州盆地及其周围地区地壳深部结构与构造的初步研究,地球物理学报,33(2):163～173。
马杏垣,1989,中国岩石圈动力学图集,北京:中国地图出版社,1～68。
徐锡伟、吴卫民、张先康等,2002,首都圈地区地壳最新构造变动与地震,北京:科学出版社,1～376。
朱金芳、徐锡伟、黄宗林等,2005a,福州市活断层探测与地震危险性评价,北京:科学出版社。
朱金芳、徐锡伟、张先康等,2005b,福州盆地及邻区地壳精细结构的深地震反射与高分辨率折射及宽角反射/折射联合探测研究,中国科学D辑,35(8):738～749。
张友南、孙君秀,1999,华北北部克拉通地壳岩石的波速特征与地壳物质组成,地震地质,21(2):147～155。
Fountain D M,Arculus R,Kay R W.,1992,Continental Lower Crust,Amsterdam:Elsevier,1～485.
Hole,J.A.,1992,Nonlinear high-resolutionthree-dimensional seismic travel time tomography,J.Geophys.Res.,97,6553～6562.
Rutter E H,et al.,1999,Synthetic seismic reflection profile through the Ivrea zone-Serie dei Laghi continental crustal section,northernwestern Italy,Geology,27(1):79～82.
ZhuJinfang,Huang Zonglin,Xu Xiwei,2005,Active Faults Exploration and Seismic Hazard Assessment in Fuzhou City,Earthquake Reserchin China,19(3):224～239.
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