黄河中游河流阶地的对比及阶地系列形成中构造作用的多层次性分析  

Comparison of River Terraces in the Middle Reach Valleys of the Yellow River and Analysis on the Multi-gradational Features of Tectonic Action in the Formation of Terrace Series

作　　者：邢成起[1,2] 丁国瑜[3,2] 卢演俦[4] 申旭辉[3] 田勤俭[3] 尹功明[4] 柴炽章[5] 韦开波[3] 

机构地区：[1]北京市地震局 [2]中国北京100029.中国地震局地质研究所 [3]中国地震局分析预报中心 [4]中国地震局地质研究所 [5]宁夏回族自治区地震局

出　　处：《中国地震》2001年第2期187-201,共15页Earthquake Research in China

基　　金：国家自然科学基金 ( 4 973 2 0 95 );地震联合基金 ( 1970 2 1;95 0 74 2 2 );国家重点基础研究发展规划项目"大陆强震机理研究与预测"( 95 13 0 10 2 )资助

摘　　要：黄河在流经青藏高原东北缘海原 -同心弧形构造区的过程中 ,发育了多达 10～ 2 1级的基座和侵蚀型阶地 ,其最大拔河高度为 4 0 1m ,最高阶地的发育年代为 1 5 7MaBP。通过对该区米家山、车木峡和黑山峡河口 3处黄河阶地以及我国北方大范围内河流阶地的对比分析发现 ,河流阶地系列形成中在构造作用上具有多层次性特征 ,即它包含了不同范围或规模和不同级次构造隆升作用所导致的阶地。研究区的黄河阶地系列可以划分为 3个层次。其中 ,第一层次的阶地共有 6级 ,为我国北方大范围内同期形成的阶地 ,它们代表 1 6Ma以来青藏高原阶段性隆升的次数 ,其隆升幅度由西向东逐渐减小 ;第二层次的阶地共有 5级 ,为海原 -天景山构造区内同期发育的阶地 ,它们代表 1 6Ma以来该构造区本身独自隆升的次数和幅度 ;第三层次阶地为发育在米家山东坡的 10级不同期阶地 ,它们代表 1 6Ma以来海原构造山地独自抬升的次数和幅度。阶地发育时间与黄土 -古土壤序列的对比还表明 ,反映青藏高原大范围构造隆升的第一层次阶地与气候变化之间有很好的可对比性 ,其形成年代均与相应古土壤发育时的间冰期对应 ,暗示导致河流下切的大范围构造抬升与强干冷期后同样可导致河流下切的气候暖湿期紧密相关 ,它们共同组成了构造 -气候旋回。In the process of the Yellow River's flow through the Haiyuan-Tongxin arc-form tectonic area on the northeastern side of the Qinghai-Xizang plateau, as many as 10～21 basis and erosion terraces have been produced, among which the biggest altitude of terraces above the river level is 401m and the formation age of the highest terraces is 1 57 MaBP. Through comparative analyses of the Yellow River terraces located separately in Mijiashan mountain, Chemuxia gorge and Heishanxia gorge and the other river terraces in the vast extent of the northern part of China, it has been discovered that the tectonic processes having resulted in the terrace series are of multi-gradation features, in another words, a terrace series at some place includes the various terraces produced by the tectonic uplifts of different scopes or scales and different ranks. The Yellow River terrace series of the study region can be divided into three grades. Among them, for the first grade there are 6 terraces altogether which are formed separately at the same time in the vast extent of the North and represent the number and magnitude of the rising of Qinghai-Xizang plateau since 1 6 Ma; for the second grade there are 5 terraces in all which are those separately simultaneously developed within the Haiyuan-Tianjingshan tectonic area and represent the number and magnitude that this tectonic area itself has uplifted alone since 1 6 Ma; for the third grade there are 10 terraces which are developed on the eastern slope of the Mijiashan mountain and represent the number and height of the uplift of the Haiyuan tectonic belt by itself since 1 6 Ma. Comparison of the terrace ages with loess-paleosol sequence has also shown that the first grade terraces reflecting the vast extent uplifts of Qinghai-Xizang plateau are very comparable with climatic changes and their formation ages all correspond to the interglacial epochs during which paleosols formed. This implies that the vast extent tectonic uplifts resulting in river downcutting are closely related to t

关 键 词：河流阶地对比 阶地系列 构造作用 多层次性 阶地成因 气候变化 黄河中游 

分 类 号：P931.1[天文地球—自然地理学]