摘要
断层滑动速率是理解复杂断层系统应变分配与评估地震危险性的重要参数,在多种研究方法中,利用构造地貌学方法限定走滑断裂的第四纪滑动速率较为普遍.在青藏高原活动断裂体系中,海原断裂带承载了部分印度-欧亚板块碰撞产生的应变,其滑动速率的精细厘定也是高原构造变形动力学分析的重要参数.过去三十年间前人采用构造地貌学方法对其进行了大量的滑动速率研究,结果位于2.3~16 mm/a之间,不同研究间相差较大,因此引发了众多争议与困惑.在对已有研究进行详细评述的基础上,指出前人研究结果不确定性的重要原因是上级阶地与下级阶地重建模型的选择.结果认为,基于两种位移累积起始时间定义的模型得到的往往是滑动速率的上限或下限,不能简单地将其等同于滑动速率真实值.当缺乏观测数据可以辅助判别两种模型的可靠程度时,应基于上、下级阶地废弃年龄同时对滑动速率进行限定,这是对滑动速率计算过程中客观存在的不确定性的尊重和认可.海原断裂带滑动速率的评估将为后续基于青藏高原内部诸多活动断裂进行两种端元变形模型合理性的分析工作提供重要的方法借鉴.
The fault slip rate of is critical for understanding strain partitioning within a fault system and assessing seismic hazard.Tectonic geomorphology method can be used in constraining Quaternary slip rates in general.In the active fault system of Tibetan Plateau,the Haiyuan Fault Zone accommodates part of Indo-Asian convergence and its slip rate provides reference for understanding the mechanics of continental deformation.Thus,several slip rate studies have been carried out along the Haiyuan fault during the past 3 decades and the results range from 2.3 mm/a to 16 mm/a,which caused controversy and confusion.Based on a review of the previous studies,we point out that the main reason for the difference in previous studies is the choice of upper terrace and lower terrace reconstruction models.We infer that the upper and lower bound of slip rates are obtained based on the two models in general,which cannot be simply equated with the real slip rate value.When there is a lack of observational data to distinguish the reliability of the two models,a combination of upper and lower terrace abandonment age constraints can be used to bracket the slip rate.The method shows the respect and recognition of the objective uncertainty in the calculation process of slip rate.In addition,the evaluation of slip rates of Haiyuan fault zone can provide a basis for the identification of two end models of the Tibetan Plateau based on the intro-block faults deformation.
作者
王子君
姚文倩
刘静
邵延秀
王文鑫
沈续文
高云鹏
徐晶
Wang Zijun;Yao Wenqian;Liu-Zeng Jing;Shao Yanxiu;Wang Wenxin;Shen Xuwen;Gao Yunpeng;Xu Jing(Institute of Surface-Earth System Science,School of Earth System Science,Tianjin University,Tianjin 300072,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;The Second Monitoring and Application Center,China Earthquake Administration,Xi’an 710054,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2024年第2期759-780,共22页
Earth Science
基金
国家重点研发计划项目(No.2021YFC3000605-04)
国家自然科学基金(Nos.U1839203,42011540385,42104061)。
