摘要
通过对活动构造、沉积地层和构造地貌的综合研究，以及运用绝对年代学和相对年代学方法得到的大量地层和地貌体的年龄数据，将河西走廊新生代构造运动划分为７个大的阶段。河西走廊新生代强烈构造运动开始于渐新世初期（约３７．７Ｍａ），盆地开始下沉并接受沉积，此后经历了渐新世中期（３０．３～２９．５Ｍａ）、渐新世末至中新世初期（２４．５～２２．２Ｍａ）、上新世中期（约４６６万年）、上新世末至更新世初期（约２４０万年）、早更新世中期（１９５～１４８万年）和中更新世以来等多次构造运动。其中上新世中期的构造运动是区域新生代构造运动的一个重要分水岭，盆地内开始接受砾岩堆积，此后构造运动明显增强；中更新世至今尤其是中更新世晚期（约１５万年）以来，盆地南缘山边带及中部横向隆起区强烈隆升。根据构造运动在各种地质地貌体上所表现出来的特征及其年龄测量数据，中更新世以来的构造运动又可划分为多次级或更次一级的构造事件。
Hexi corridor,located on the northern margin of the Qinghai Xizang plateau,is one of the most typical regions of compressional tectonic basins in northwest China.Accompanying the uplift of the Qinghai Xizang plateau since the late Paleogene,the four basins of the corridor began subsiding and accepting deposits.Since then,at least seven tectonic movement stages can be identified.According to the results of absolute dating(includes ESR,TL and IRSL dates) and relative dating(includes rock weathering rinds and palaeomagnetic stratigraphy) of Cenozoic strata and landforms,the seven movements occurred at about 37.7,30.3～29.5,24.5～22.2,4.66,2.47～2.23,1.95～1.48 and 080Ma～present,each of them represented by uncomformity and deformation of strata,active folding and faulting,and geomorphic evolution. The first tectonic movement stage took place at the beginning of Oligocene after a long period of erosion and denudation since the late Cretaceous.The forth stage,characterized by the preliminary accumulation of gloomy conglomerate (Yumen formation),is the turning point of Cenozoic tectonic movement as the intensity of tectonic activity became obviously stronger.It is in the latest stage that the main part of modern landform evolved.Some important morphologic units,including piedmont platform,transverse uplifts and northern mountains,generated or strongly deformed and uplifted in the stage.On the other hand,less deform tracks can be found in strata. Further divisions are made in order to avoid that the interval time between two neighbouring movements became shorter and shorter as time passed because latelyformed records preserved better.For example,mainly according to the luminescence ages of river terraces,at least five tectonic substages can be identified during the latest stage.They started at about 800,350,250,150 and 40ka respectively.Furthermore,in the tectonic substage started from 150ka,four tectonic events,which took place at 145,110,90 and 70ka respectively,can be identified,and in the last substage,three tectonic events(40,30 and 10ka) can be identified.
出处
《北京大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
1998年第4期523-532,共10页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金
