邢台地区深浅构造耦合关系的探测研究和几个值得思考的问题
|
摘要
根据“九五”期间在邢台震区开展的深浅构造耦合关系探测研究的结果 ,以及以往在该区开展的深地震测深、深地震反射和石油地震勘探工作的结果 ,指出邢台大震震源区深约8km处的滑脱面以上的上地壳存在一系列浅层断裂 .其中 ,除新河断裂向上错断了中更新统地层 ,艾新庄断裂和其它断裂均未错断第四系地层 .艾新庄断裂等向下归并于新河断裂 ,而新河铲形断裂则以低倾角向下延伸归并于滑脱面 .滑脱面以下存在的贯穿中、下地壳直至Moho面的高倾角深大断裂是邢台大震的发震断裂 .它的错动引起大震 ,并引起浅层断裂的活动和地表土层物质的运动 .上地壳的浅层断裂不是大震的发震断裂 ,但可能是活动断裂 .滑脱面的存在使深、浅构造之间形成既彼此相对独立、又相互影响的特殊关系 .它在上、下地壳之间传递部分能量和形变 ,同时又具有一定的解耦作用 .最后 ,提出活动断裂不一定错断最新地层 ,断裂所错断的最上部地层的年代也不一定就是该断层最近的活动年代 .这对活断裂年代的判定和研究提出了一个值得思考的问题 .本文还提出了其它值得思考的问题 .
WT5BZ]In the light of results from study on the coupled relationship between deep and shallow structures in Xingtai earthquake area during the “Ninth Five Year Plan”period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault, reaches the Quaternary stratum, except that the Xinhe fault cut through the mid Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault, whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the Xingtai large earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other. It not only transmits partial energy and deformation between the upper and lower crust, but also has a certain decoupling effect. Finally we conclude that active faults do not necessarity reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also referred to in this study.
WT5BZ]In the light of results from study on the coupled relationship between deep and shallow structures in Xingtai earthquake area during the “Ninth Five Year Plan”period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault, reaches the Quaternary stratum, except that the Xinhe fault cut through the mid Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault, whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the Xingtai large earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other. It not only transmits partial energy and deformation between the upper and lower crust, but also has a certain decoupling effect. Finally we conclude that active faults do not necessarity reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also referred to in this study.
引文
国家地震局赴美专家代表团 . 1 995. 1 994年 1月 1 7日美国加州北岭地震现场考查报告 [J].国际地震动态 ,( 3 ) :1 5～ 2 2
河北省地震局 . 1 986.一九六六年邢台地震 [M].北京 :地震出版社 ,58～ 68
王椿镛 ,王贵美 ,林中洋 ,等 . 1 993 .用深地震方法研究邢台地震区地壳细结构 [J].地球物理学报 ,3 6( 4) :4 45～ 4 52
王椿镛 ,张先康 ,吴庆举 ,等 . 1 994 .华北盆地滑脱构造的地震学证据 [J].地球物理学报 ,3 7( 5) :61 4～ 62 0
徐杰 ,方仲景 ,杨理华 . 1 988. 1 966年邢台 7.2级地震的构造背景和发震构造 [J].地震地质 ,1 0 ( 4) :51～ 59
朱令人 ,苏乃秦 ,杨马陵 . 1 998. 1 997年新疆伽师强震群及三次成功的临震预报 [J].中国地震 ,1 4 ( 2 ) :1 0 1～ 1 1 5
祝治平 ,张先康 ,盖玉杰 ,等 . 1 995.邢台震源区及相邻地区地壳上地幔速度结构研究 [J].地震学报 ,1 7( 3 ) :3 2 8～ 3 3 4
河北省地震局 . 1 986.一九六六年邢台地震 [M].北京 :地震出版社 ,58～ 68
王椿镛 ,王贵美 ,林中洋 ,等 . 1 993 .用深地震方法研究邢台地震区地壳细结构 [J].地球物理学报 ,3 6( 4) :4 45～ 4 52
王椿镛 ,张先康 ,吴庆举 ,等 . 1 994 .华北盆地滑脱构造的地震学证据 [J].地球物理学报 ,3 7( 5) :61 4～ 62 0
徐杰 ,方仲景 ,杨理华 . 1 988. 1 966年邢台 7.2级地震的构造背景和发震构造 [J].地震地质 ,1 0 ( 4) :51～ 59
朱令人 ,苏乃秦 ,杨马陵 . 1 998. 1 997年新疆伽师强震群及三次成功的临震预报 [J].中国地震 ,1 4 ( 2 ) :1 0 1～ 1 1 5
祝治平 ,张先康 ,盖玉杰 ,等 . 1 995.邢台震源区及相邻地区地壳上地幔速度结构研究 [J].地震学报 ,1 7( 3 ) :3 2 8～ 3 3 4
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心