干盐池拉分盆地的形成时代及内部新生断层的大地震响应

项目名称： 干盐池拉分盆地的形成时代及内部新生断层的大地震响应

项目编号： No.41272214

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 冉勇康

作者单位： 中国地震局地质研究所

项目金额： 102万元

中文摘要： 干盐池拉分盆地是位于青藏高原东北缘的海原活动断裂带内次级断层呈左阶左旋运动的产物，盆地的形成时间显示海原断裂带左旋运动的开始；再者，1920年海原8.5级大地震震中即位于该盆地附近，已有研究显示大地震的发生与拉分盆地内部新生断层联系密切。本计划拟以干盐池盆地发育演化的精细研究为切入点，通过地表地质调查、地球物理探测、钻孔探测和槽探结合等多种途径，并利用14C法、宇宙成因核素法、古地磁法依次约束、校正的埋藏地层测年技术，同时结合孢粉分析法，1）研究干盐池拉分盆地的形成时代，即海原活动断裂带左旋走滑活动开始的时代，为青藏高原东北缘最新一期构造运动样式转换发生的时代提供新证据；2）研究拉分盆地内部新生断层的生长模式、晚第四纪古地震序列，探讨该断层生长与大地震发生之间的响应关系，分析干盐池拉分盆地在海原活动断裂带大地震孕育过程中所起的作用，丰富断层几何不连续贯通和断层生长理论的研究实例。

中文关键词： 干盐池拉分盆地；左旋走滑起始时间；内部新生断层；地震活动特征；演化模式

英文摘要： The Ganyanchi pull-apart basin is a product of left-stepping sinistral movement of two secondary strike-slip faults in the Haiyuan Fault Zone, Northeastern Tibetan Plateau. Therefore, the formation age of the basin can be considered as the start age of the sinistral movement of the Haiyuan Fault Zone. Furthermore, the epicenter of the 1920 M8.5 Haiyuan Earthquake was located near the basin, and the existing research results show that the large earthquakes occurred pull-apart basins keep close contact with the newborn faults inside these basins. This plan intends to take the intensive search of the development and evolution of the Ganyanchi basin as the through point, using several domains and techniques, such as surface geological investigation, geophysical exploration, drilling, trenching, buried sediments dating method (14C method, cosmogenic nuclides methods, paleomagnetic method and pollen analyses method), et al., to study 1) the formation age of the Ganyanchi pull-apart basin-the start age of the sinistral movement of the Haiyuan Fault Zone, meantime, to provide a new evidence for the age of the latest transformation of structural styles of the northeastern Tibetan Plateau. 2) the growth model and the paleoearthquake sequences of the intrabasinal newborn fault, the response relation between this fault grow

英文关键词： Salt Lake pull-apart basin；start time of the strike-slip movement；cross-basin fault；seismic activity；evolution model