用钻孔地层剖面记录恢复古地震序列:河北夏垫断裂古地震研究
|
摘要
本文介绍了利用钻孔构造地层学和年代学资料鉴定平原区隐伏活动断裂长期活动习性的一种新的方法和应用实例。通过夏垫断裂上下盘东柳河屯 1,2号钻孔地层剖面年代学的测定和岩性的分析与对比 ,定量地恢复了距今 2 6ka以来断裂上下盘的差异沉积历史和垂直错动过程 ,建立了鉴别古地震的构造地层学标志。在此基础上 ,将断裂两侧的累积垂直位移量作为定量约束条件从新到老恢复到每一次地表破裂型地震错动前的状态 (扣除后期的同震垂直位移量 ) ,可识别出 11次地表破裂型古地震事件。指出夏垫断裂上的地表破裂型地震复发行为与古气候环境之间存在着密切的相关关系 ,气候极度寒冷的末次冰期间亚冰期和鼎盛期 (距今 19 3～ 2 6ka)共发生 6次地表破裂型古地震事件 ,这一时期是夏垫断裂地表破裂型 (古 )地震丛状群集期 ,复发间隔介于 90 0～ 190 0a ,且多数仅 90 0～ 12 0 0a。末次冰期鼎盛期晚期到冰后期 (距今 0～ 19 3ka)的地表破裂型 (古 )地震服从准周期复发模式 ,复发间隔明显地增长 ,包括公元 16 79年三河 -平谷 8级地震在内的最近 5次地表破裂型(古 )地震的复发间隔介于 370 0～ 580 0a。
The Xiadian fault is one of the most important concealed active faults in the northern part of the North China Plain. The Sanhe-Pinggu earthquake (M=8) is the latest surface rupturing event on this fault. Two stratigraphic drill logs on both sides of the Xiadian fault are chronologized by using thermoluminescene and 14 C dating methods. Comparison shows a differential sedimentation on both sides of the fault in the last 26 ka B.P. The stratigraphic marks are established for identifying paleoearthquakes in the drill logs and 11 events are recognized. The main results of this study include: (1)The vertical slip of the Xiadian fault decreased since the Last Glacial Maximum in the past 26ka B.P. The vertical slip rate reached 1.2mm/a during the period of 21～26 ka B.P., 0 98mm/a during the period of 10～21 ka and 0.34mm/a in the past 10 ka B.P., respectively. (2)11 paleoearthquakes are identified by the drill logs which indicate an irregular recurrence behaviour in the past 26ka B.P. The paleoearthquakes clustered with a relatively short interval of 900～1 200 years in the Last Inter-Stadial and Last Glacial Maximum (19.3～26 ka B.P.), while several paleoearthquakes recurred quasi-periodically with an interval of 3 770～5 800 years in the Post Glacial. (3)The paleoearthquake recurrence pattern seems to be associated with paleo-climate variation in the Last Glacial. The earthquake clustering occurred in the Last Inter-Stadial and Last Glacial Maximum with a short recurrence interval. The recurrence interval became longer in the Post Glacial.
The Xiadian fault is one of the most important concealed active faults in the northern part of the North China Plain. The Sanhe-Pinggu earthquake (M=8) is the latest surface rupturing event on this fault. Two stratigraphic drill logs on both sides of the Xiadian fault are chronologized by using thermoluminescene and 14 C dating methods. Comparison shows a differential sedimentation on both sides of the fault in the last 26 ka B.P. The stratigraphic marks are established for identifying paleoearthquakes in the drill logs and 11 events are recognized. The main results of this study include: (1)The vertical slip of the Xiadian fault decreased since the Last Glacial Maximum in the past 26ka B.P. The vertical slip rate reached 1.2mm/a during the period of 21～26 ka B.P., 0 98mm/a during the period of 10～21 ka and 0.34mm/a in the past 10 ka B.P., respectively. (2)11 paleoearthquakes are identified by the drill logs which indicate an irregular recurrence behaviour in the past 26ka B.P. The paleoearthquakes clustered with a relatively short interval of 900～1 200 years in the Last Inter-Stadial and Last Glacial Maximum (19.3～26 ka B.P.), while several paleoearthquakes recurred quasi-periodically with an interval of 3 770～5 800 years in the Post Glacial. (3)The paleoearthquake recurrence pattern seems to be associated with paleo-climate variation in the Last Glacial. The earthquake clustering occurred in the Last Inter-Stadial and Last Glacial Maximum with a short recurrence interval. The recurrence interval became longer in the Post Glacial.
引文
李鼎容 ,彭一民 ,刘清泗 ,等 .1979.北京平原区上新统 -更新统的划分 .地质科学 ,(4 ) :342～ 349.
孟宪梁 ,杜春涛 ,王瑞 ,等 .1983.16 79年三河 -平谷大地震的地震断裂带 .地震 ,(3) :18～ 2 3.
彭一民 ,李鼎容 ,谢振钊 ,等 .1981.北京平原区同生断裂的某些特征及其研究意义 .地震地质 ,3(2 ) :57～ 6 4 .
向宏发 ,方仲景 ,徐杰 ,等 .1988.三河 -平谷 8级地震区的构造背景与大震重复性研究 .地震地质 ,10 (1) :15～ 2 8.
向宏发 ,方仲景 ,贾三发 ,等 .1994 .隐伏断裂研究及其工程应用 -以北京平原区为例 .北京 :地震出版社 .58～76 .
冉勇康 ,邓起东 ,杨晓平 ,等 .1997.16 79年三河 -平谷 8级地震发震断层的古地震及其重复间隔 .地震地质 ,19(3) :193～ 2 0 2 .
孙建中 ,赵景波 .1991.黄土高原第四纪 .北京 :科学出版社 .2 4 2页 .
ThompsonLG ,TYao ,DavisME ,etal.1997.Tropicalclimateinstability :thelastglacialcyclefromaQinghai Tibetanicecore .Science ,2 76 :182 1～ 182 5.
孟宪梁 ,杜春涛 ,王瑞 ,等 .1983.16 79年三河 -平谷大地震的地震断裂带 .地震 ,(3) :18～ 2 3.
彭一民 ,李鼎容 ,谢振钊 ,等 .1981.北京平原区同生断裂的某些特征及其研究意义 .地震地质 ,3(2 ) :57～ 6 4 .
向宏发 ,方仲景 ,徐杰 ,等 .1988.三河 -平谷 8级地震区的构造背景与大震重复性研究 .地震地质 ,10 (1) :15～ 2 8.
向宏发 ,方仲景 ,贾三发 ,等 .1994 .隐伏断裂研究及其工程应用 -以北京平原区为例 .北京 :地震出版社 .58～76 .
冉勇康 ,邓起东 ,杨晓平 ,等 .1997.16 79年三河 -平谷 8级地震发震断层的古地震及其重复间隔 .地震地质 ,19(3) :193～ 2 0 2 .
孙建中 ,赵景波 .1991.黄土高原第四纪 .北京 :科学出版社 .2 4 2页 .
ThompsonLG ,TYao ,DavisME ,etal.1997.Tropicalclimateinstability :thelastglacialcyclefromaQinghai Tibetanicecore .Science ,2 76 :182 1～ 182 5.
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