临潼—长安断裂第四纪活动性勘探

Exploration on Lintong-Chang′an Fault for Its Activities since Quaternary Period

临潼—长安断裂是西安市附近的一条重要活动断裂,影响到西安市部分扩展区域的发展。本文主要采用浅层地震勘探、钻探以及年代学方法对临潼—长安断裂的活动性进行判定。浅层地震勘探结果反映临潼-长安断裂错断第四纪以来的多套地层,错距自下而上在逐渐减小,反映了断裂长期以来的生长特性。钻孔联合地质剖面显示该断裂错断了中更新世的粗砂及粘土层,错距在8.7～2.5m之间。由下至上减小的活动速率反映了该断裂的活动在减弱。

Lintong-Chang＇an fault is an important active fault near Xi′an city.It may affects the development expansion region of Xi′an.In this paper the activity of the fault is discussed by using high-resolution shallow seismic reflection,composite drilling and dating methods.The result of seismic reflection shows that some layers in Quaternary were offseted and the dislocated distances decrease from deep layer to upper one,means a continual longtime active of the fault.The geological sections of composite drilling shows that sand and clay layers of middle Plaistocene were cut and the displacements are in 8.7-2.5 m.All of this prove that active rate of the fault decreased from early to late Pleistocene Epoch.