河套地区全新世黄河古河道迁移演化规律及其成因机制

发布时间：2018-05-08 14:44

  本文选题：河套地区 + 黄河古河道　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：古河道的迁移摆动记录着河流系统的自身发育历史,同时又反映古地理环境与地貌的演变过程。黄河古河道是河套平原区第四纪水文网的重要组成部分,为全新世河套平原地貌演化的重要证据,而全新世黄河古河道的迁移摆动则对反演河套盆地水系演化、气候变迁及新构造运动具有重要的研究意义。本文通过Landsat8遥感影像解译、1:5万野外地质地貌调查、钻孔资料分析,结合剖面实测、物探等技术手段,精准的圈定了黄河地表及埋藏古河道的分布位置;采用OSL与14C测年较精确地确定了黄河古河道的年代,对全新世黄河古河道进行分期,以此获得了本区古河道丰富的古地理信息,并最终对黄河古河道迁移演化的成因机制进行了详细的探讨。全新世以来黄河古河道可分为五期:Ⅰ期古河道,分南北两支,南支分布在复兴镇西北部,埋深2~6m,北支分布于呼勒斯太中南部,埋深8.2~9m,时代为9.93~7.4kaB.P.;Ⅱ期古河道,河道主体分布在色尔腾山山前,埋藏于现今乌加河古河道下部4~11m处。在塔尔湖区分布有同一期的古河道,埋深7~9m,时代7.4~4.1kaB.P.;Ⅲ期古河道,呼勒斯太中部、塔尔湖中南部及复兴镇南部都曾发育,但河道主体为塔尔湖区的古河道,埋深2~9m,时代为4.1~1.2kaB.P.。Ⅳ期古河道,埋藏深度为2.5~4m,主体分布在复兴镇地区,自西南向东北并折向东南,时代为1.2~0.4kaB.P。Ⅴ期古河道(现今黄河),沿鄂尔多斯北缘断裂自西而东流,河道游荡形成了宽约4~5km东西向河道区域,近期经人类修筑,河道趋于稳定,时代为0.2kaB.P~至今。近万年来,黄河在河套地区频繁改道,迁移的整体路径呈现由阴山山前逐渐向南迁移、最后摆动至现今河道的趋势。迁移的具体过程为早全新世的南北两支古河道向南微弱的迁移趋势,且分散为南、中、北三支河道;至晚全新世早期的以塔尔湖为中心的大范围网格状河道水系,到晚全新世中期的古河道又减少为南北两支,且北支逐渐由主流级别降为支流,最后晚全新世晚期至今的北部北支河道干涸,形成南支为主流的现代黄河形态。河道迁移演化的其主控因素为活动断裂及古地震活动导致的地表不稳定,同时全新世的气候干湿多变导致的水文变化及后期人类活动的影响也是黄河古河道迁移的重要影响因素。
[Abstract]:The migration and wobble of paleochannel record the development history of the river system and reflect the evolution process of paleogeographic environment and geomorphology at the same time. The paleochannel of the Yellow River is an important part of the Quaternary hydrological network in the Hetao Plain, which is an important evidence of the geomorphologic evolution of the Holocene Hetao Plain. The migration and swing of the paleochannel of the Yellow River in the Holocene can reverse the evolution of the drainage system of the Hetao Basin. Climate change and neotectonic movement are of great significance. In this paper, the distribution of the surface and buried paleochannel of the Yellow River is accurately delineated by the interpretation of the Landsat8 remote sensing image, the field geological and geomorphological investigation, the analysis of the borehole data, the combination of the profile measurement, geophysical prospecting and other technical means. By using OSL and 14C dating, the paleogeography of the Yellow River is accurately determined, and the paleogeographic information of the paleo-channel in this area is obtained by stages of the Holocene Yellow River. Finally, the formation mechanism of paleochannel migration and evolution of the Yellow River is discussed in detail. Since the Holocene, the paleochannel of the Yellow River can be divided into five periods: stage I, paleochannel, divided into north and south, the southern branch is located in the northwest of Fuxing town, the buried depth is 2 ~ 6 m, the north branch is distributed in the central and southern part of Hulas, the buried depth is 8.2 m, and the age is 9.93 ~ 7.4kaB.P. The main body of the river is located in front of the Serten Mountains and buried at 411m in the lower part of the ancient channel of the present Wujia River. In the Tal Lake region, there are ancient rivers in the same period, with a buried depth of 7 ~ 9 m and an age of 7.4 ~ 4.1 kaB.P.; in the third stage, the paleochannel, the central part of Hulatai, the central part of Lake Tal and the southern part of Fuxing Town, are all developed, but the main body of the channel is the paleochannel of Tal Lake area. The buried depth is 2 ~ 9 m, the age is 4.1 ~ 1.2kaB.P..鈪，

本文编号：1861812