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| 以海原断裂甘肃老虎山段为例浅析走滑断裂古地震记录的完整性——兼论古地震研究中的若干问题 | |
| 引用本文： | 刘静,徐锡伟,李岩峰,冉勇康.以海原断裂甘肃老虎山段为例浅析走滑断裂古地震记录的完整性——兼论古地震研究中的若干问题[J].地质通报,2007,26(6):50-660. |
| 作者姓名： | 刘静 徐锡伟 李岩峰 冉勇康 |
| 作者单位： | 1. 中国科学院青藏高原研究所,北京,100085 2. 中国地震局地质研究所,北京,100029 3. 中国地震局地震应急搜救中心,北京,100049 |
| 基金项目： | 国家自然科学基金面上项目(编号:40672141、40474037)资助 |
| 摘 要： | 在简单介绍海原断裂老虎山段松山探槽点古地震工作的基础上,分析了制约走滑断裂上古地震记录完整性的因素。松山探槽点跨断裂开挖的2个探槽揭示颜色和粒度不同的地层互层的沉积序列呈近水平面状展布。在断裂带内地层发生错断、旋转和拖曳等变形现象。多个层位上的这种变形表明该点揭示了6次古地震事件。炭屑的~(14)C年龄限定了6次事件均发生在距今3500～3900年以来,其中最新的4次事件从老到新分别为0～410aAD、890～1000年之后不久、1440～1640 aAD和1990年景泰-天祝Mw5.8级历史地震。该序列及其他例子表明连续的、高沉积速率的微构造环境是走滑断裂上探槽选取的重要原则。 |
| 关 键 词： | 走滑断裂 古地震 探槽位置选择 高沉积速率环境 海原断裂 甘肃 |
| 文章编号： | 1671-2552（2007）06-0650-11 |
| 收稿时间： | 2007-02-14 |
| 修稿时间： | 4/2/2007 12:00:00 AM |
On the completeness of paleoseismic records of strike-slip faults: an example from the Laohushan segment of the Haiyuan fault in Gansu,China, with a discussion of several problems in the paleoearthquake study |
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| LIU Jing,XU Xi-wei,LI Yan-feng,RAN Yong-kang.On the completeness of paleoseismic records of strike-slip faults: an example from the Laohushan segment of the Haiyuan fault in Gansu,China, with a discussion of several problems in the paleoearthquake study[J].Geologcal Bulletin OF China,2007,26(6):50-660. | |
| Authors: | LIU Jing XU Xi-wei LI Yan-feng RAN Yong-kang |
| Institution: | 1 Institute of Qinghai-Tibet Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;2 Institute of Geology, China Earthquake Administration, Beijing 100029, China;3 National Earthquake Rescue and Support Services, China Earthquake Administration, Beijing 100049, China |
| Abstract: | In this paper,taking for example the paleoseismic investigation of the Laohushan segment of the Haiyuan fault,the authors analyze the constraints on the completeness of paleoseismic records.Two fault-perpendicular trenches at the Songshan trench site have revealed that nearly horizontally-bedded sedimentary layers with alternating colors and grain sizes are offset, rotated and sheared.Such deformations in multiple stratigraphic horizons demonstrate the occurrence of six paleoseismic events. ~(14)C dating of charcoal from the trenches determines that all the six events occurred during the past 3500-3900 years,of which the youngest four events took place,from the oldest to youngest,during 0-410a A.D.,shortly after 890-1000a A.D., during 1440-1640a A.D.and in 1990 when the Jingtai-Tianzhu Mw=5.8 earthquake took place.This record and other exam- ples suggest that the structural environment with few or no depositional hiatuses and high rates of sedimentation are the best sites for trenching in a strike-slip fault. |
| Keywords: | strike-slip fault paleoearthquake trench site selection location with high rates of sedimentation Haiyuan fault |
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