川藏铁路金沙江断裂带北段第四纪活动特征探讨

川藏铁路跨越金沙江断裂带北段,后者的第四纪地质地貌特征从构造上控制了川藏铁路的地质选线工作。金沙江断裂带北段由多条断裂组成,根据区域内地层分布状况、显微构造和岩层变质程度等可以鉴定出4条主要的深切地壳的大型断裂,这4条断裂自西向东即字嘎寺-德钦断裂、波罗-通麦断裂、金沙江主断裂带和岗托-义敦断裂。通过野外地质地貌调查和地质测年,本次研究认为字嘎寺-德钦断裂东支、西支马曲河北段和岗托-义敦断裂第四系以来可能不再具有活动性,而字嘎寺-德钦断裂西支马曲河南段、波罗-通麦断裂和金沙江主断裂带南段部分段落具有Q3活动性。

Discussion on Quaternary Activity Characteristics of Northern Section of Jinshajiang Fault Zone along Sichuan-Tibet Railway

The Sichuan-Tibet railway crosses over the northern section of Jinshajiang fault zone.The Quaternary geological and geomorphological characteristics of the fault zone control the geological route selection of the Sichuan-Tibet Railway from the tectonics.The northern section of Jinshajiang fault zone is composed of several faults.According to the distribution of strata,micro-structure and the degree of rock metamorphism in the region,four major large-scale deep crustal faults can be identified,from west to east they are Zigasi-Deqin fault,Boluo-Tongmai fault,Jinshajiang main fault zone and Gangtuo-Yidun fault.Through geological and geomorphological investigation and geological dating,this study concludes that the Eastern Branch of Zigasi-Deqin fault,the northern section of the Maqu River of the Western Branch and Gangtuo-Yidun fault may no longer be active since the Quaternary,while the southern section of the Western Branch of Zigasi-Deqin fault,the southern section of the Maqu River,Boluo-Tongmai fault and the southern section of Jinshajiang main fault zone may be of Q3 activity.