河西走廊地壳稳定性研究进展

ADVANCES IN STUDY OF CRUSTAL STABILITY IN HEXI CORRIDOR,NORTHWESTERN CHINA

河西走廊地区地处青藏高原北缘,是一个典型的压陷盆地,周边主要活动断裂带有:龙首山南缘活动断裂带、祁连山北缘活动断裂带、昌马活动断裂带及阿尔金活动断裂带东段。河西走廊南侧是地球物理场和地壳结构骤变带,龙首山南缘活动断裂带和祁连山北缘活动断裂带巨大的逆冲造就了走廊地区巨厚的中新生代沉积,最大厚度超过3500m～4000m,其中第四系沉积物最厚超过1000m。河西走廊及邻区大地形变强烈,更是地震活动带,历史上和现今发生了许多破坏性大地震和众多中小地震。从活动断裂带角度考虑,包括与西气东输管线、兰新铁路和312国道以不同角度斜交的阿尔金断裂带东段(上赤金—宽滩山一带)、嘉峪关断裂带、榆木山断裂带都是现今构造活动性比较强烈的断裂带,它们的活动性包括长期蠕变和瞬间变形,必将对上述工程管线和交通干线的安全性产生影响。

Hexi corridor,tectonically located in the northeastern margin of the QinghaiXizang plateau,is a typical compressive fault basin.Around it,there developed Altun active fault,northern Qilianshan boundary active fault,Changma active fault and southern Longshoushan boundary active fault.There are sudden changes of geophysical field,crustal thickness and lithosphere structure in the area.The giant thrusting displacements along the northern Qilianshan boundary active fault and southern Longshoushan boundary active fault result in the huge MesozoicCenozoic sediment,more than 3500～4000m in some place,in which,the thickness of Quaternary sediment is more than 1000m.Hexi corridor is also a belt of stronger deformation and seismic activity.There happen many destructive earthquakes and a lot of midsmall earthquakes in history and nowdays. Specially,the eastern Altun fault,the Jiayuguan fault and the Yumushan fault,which cross the west to east gas transportation pipeline,the LanzhouXinjiang railway and 312 highway in different angle,are the present active fault. The deformation of these active faults,including longterm creep and instantaneous sliding (eg.earthquake),influences the safety of main line of communication and gas transportation pipeline.