祁连山东段发育了多条大型活动断裂,如近东西向展布的天桥沟-黄羊川断裂及北西西向展布的金强河断裂、毛毛山断裂、老虎山断裂等,在马雅雪山北麓、宝泉山隆起北缘还发育了一条整体呈北西-北西西向展布的马雅雪山断裂.其中,前人已对天桥沟-黄羊川断裂、金强河断裂、毛毛山断裂、老虎山断裂的晚第四纪活动开展了大量的研究,相比而言,马雅雪山断裂的研究程度还较低,其最新构造活动特征及其与区域主干活动断裂之间的关系等尚不清楚.马雅雪山断裂构成了天祝盆地与南部山体、丘陵的分界线,迹线清晰,断层三角面、断层槽谷多见,局部冲洪积阶地可见线性展布的断层陡坎,显示出断裂在晚第四纪有一定的活动.本研究对马雅雪山断裂西部的金强河段开展了实地调查,重点对马营沟及小黑刺沟2处的阶地断层陡坎开展了高精度地形地貌测量及阶地地貌面定年,对滑动速率进行了厘定.研究结果表明,马雅雪山断裂金强河段晚第四纪活动显著,断裂最近强震活动发生在8.21～3.43 ka BP,晚更新世晚期以来的垂直滑动速率为0.45～0.63 mm/a.
Late Quaternary Faulted Landforms and Determination of Slip Rate of Jinqanghe Segment of Maya Snow Mountain Fault
Several large active faults have developed in the eastern section of the Qilian Mountains,including the near east-west trending Tianqiaogou-Huangyangchuan fault,the northwest-west trending Jinqianghe fault,Maomaoshan fault,Laohushan fault,and the northwest to northwest-west trending Maya Snow Mountain fault.While extensive research has been conducted on the late Quaternary activity of the Tianqiaogou-Huangyangchuan,Jinqianghe,Maomaoshan,and Laohushan faults,the Maya Snow Mountain fault remains comparatively under-researched,particularly in terms of quantitative studies.The recent activity characteristics and relationship with the regional active faults remain unclear.The Maya Snow Mountain fault,which extends approximately 150 km and passes through Tianzhu city and several villages,serves as the boundary between the Tianzhu basin and the southern mountains and hills.Fault triangles and troughs are common along this fault,and linear fault scarps are visible on some alluvial and proluvial terraces,suggesting activity during the late Quaternary.Given its proximity to populated areas,further investigation into its activity is crucial.In this study,we focus on the Jinqianghe segment of the Maya Snow Mountain fault,located in the fault's western section.We conducted high-preci-sion topographic and geomorphic measurements,dated terraces,and determined fault slip rates at the Maying River and Xiaoheici River fault scarps.Our findings indicate that the Jinqianghe segment of the Maya Snow Mountain Fault was significantly active during the late Quaternary and remains active into the early Holocene.A strong earthquake occurred at 8.21～3.43 ka BP,with vertical slip rate since the late Pleistocene estimated at 0.45 to 0.63 mm/a.
万方数据
维普
