【作者】 王均平；

【导师】 潘保田；

【作者基本信息】 兰州大学 ， 自然地理学， 2006， 博士

【摘要】 黄河是我国的第二大河,以多沙、易淤、善徙、善决而著称于世,特别是黄河中游,一方面缺水少水,另一方面水土又严重流失,因而利用黄河、开发黄河迫在眉睫。 鄂尔多斯是黄河中游构造活动较稳定的地块,虽然它远离青藏高原,但高原隆升的远程效应至少通过两种途径传递到该地区,即通过阿尔金断裂和昆仑山断裂系向东向北传递。阿尔金走滑断裂是青藏高原北部的一条重要断裂带,它通过祁连山断裂,向东最终与海原六盘山断裂相连,地块的向东走滑最终作用于鄂尔多斯地块,促使其整体抬升及逆时针旋转;另一途径,高原挤压应力通过昆仑山断裂、太白断裂、秦岭断裂向东传递,作用于鄂尔多斯地块,并促使了该地块周边的渭河地堑及山西地堑的发育与扩展。 因而,研究该区黄河水系的形成演化对于了解鄂尔多斯的构造活动、青藏高原的远程效应、进而利用、治理黄河具有深远的科学意义。然而,当前对该地区的河流演化历史存在较大的分歧,严重阻碍了学科的发展,进一步开展黄河中游水系、地貌的形成演化历史研究,具有重要的现实意义,同样也具有重大的理论价值。 本文对黄河中游晚新生代以来地貌演化与河流阶地发育进行了初步研究,基于野外的大量考察,典型剖面样品采集,粒度、磁化率等指标测试分析,以可靠的古地磁、TL等测年数据,初步确立了黄河中游流水地貌演化的过程,并得出以下结论: (1)与青藏高原主夷平面发育一致,黄河中游唐县面发育于22—3.6 Ma,并形成于4.5-3.6 Ma左右,在该面上沉积了典型风成红粘土;在唐县面发育期间,受青藏高原隆升挤压的影响,于～8.4 Ma鄂尔多斯内部保德附近出现构造变形并形成一些规模较小内陆湖泊,并且在湖泊的周围先后发育了流向古湖的古河流,但这次构造活动并没有终止唐县面的发育,鄂尔多斯主体仍处于剥蚀夷平过程中,在湖泊中接受了该时期的相关沉积。 (2)受青藏运动A幕强烈隆升影响,差异性隆升增强,地形出现较大分异,唐县期夷平面最终于3.6 Ma开始强烈解体,保德古湖此时结束湖相沉积,并在湖相地层之上开始堆积风成红粘土;在吴堡唐县面之上,也开始堆积风成红粘土。 (3)在晋陕峡谷的北面于4.9 Ma就开始发育河流,它们流向保德附近的古湖,约3.6 Ma左右再次下切,但随着青藏运动的强烈隆起,唐县面强烈解体,古湖沉积结束,河流也逐渐消失。 (4)3.6-1.2Ma,为黄河水系组织时期,各地以盆地为基准进行溯源侵蚀,形成一些短小的河流,该时期为黄河的形成建立基础。约1.2 Ma,黄河贯通三门峡东流入海,更多还原

【Abstract】 The Yellow River is the second longest river in china, it is well known for "abundant sediment, channel migration, channel fill and levee break". There are two significant problems in the middle reaches of the Yellow River: firstly, the lack of water;secondly, the serious water and soil loss. So it is urgent to exploit and utilize the Yellow River.The Ordos Plateau is a steady block. Although the Ordos Plateau is far from Tibetan Plateau, the long-distance effect of Tibetan Plateau uplift transmits to it at least in two ways, that is, across the Altyn Tagh strike-slip fault to east and across the Kun-lun Mountains Fault System to northeast. The Altyn Tagh is one of the significant fault zones at the north part of Tibetan Plateau, it transmitted the stress to Qilian fault and then to Haiyuan-Liupanshan fault by intensive strike slip, which made the Ordos Plateau Block upheave and circumgyrate anticlockwise. In the other way, Tibetan Plateau stress had effect on the Ordos Plateau Block by Kunlun Mountains fault, Taibai fault, Qinling fault and at last speeded up the development and expansion of Weihe rift valley and Shanxi rift valley.So, studies about the formation and evolution of the Yellow River have a significant meaning in science for us to study the tectonic movement of the Ordos block, the long-distance effect of the Tibetan Plateau, the exploitation and utilization of the Yellow River. Whereas there are still many different opinions on the study about the formation of the Yellow River, it seriously blocked the development of earth science. An advanced study into the formation and evolution of the water system and landform in the middle reaches of the Yellow River has not only practical meaning but also academic value.This paper has made a primary study for the evolution of the geomorphologic evolution and the development of the Yellow River. It has built the process of the fluvial landform evolution in the middle reaches of the Yellow River based on numerous field survey, the analysis of particle size and magnetic susceptibility, reliable paleomagnetism data and TL data. Some important conclusions are drawn as following:(1) The planation surface of Tangxian developed at 22-3.6 Ma, which is the same with the main surface of Qinghai-Tibet Plateau. It shaped up at about 4.5-3.6 Ma and was covered with typical aeolian red clay. During the development of Tangxian surface, some tectonic deformations appeared in Ordos at about 8.4 Ma affected by the uplift of Tibetan Plateau. Italso formed many small endorheic lakes, around which some paleo-rivers flowed into these lakes. But this tectonic movement didn’t collapse the development of Tangxian surface, Ordos was still eroded and planed, and the lakes as a depression received the deposition at the same time.(2) Affected by uplift of the Qingzang movement (phase A), otherness upheaval was strengthened, the difference of the surface relief appeared, Tangxian planation surface began to dismantled at 3.6 Ma, endorheic lakes and rivers into them began to disappear.(3) The topmost river terrace near Hequ indicates that a river had started to develop its stream about 4.9 Ma, and it flowed into the Baode paleolake. Another intensive incision happened at about 3.6 Ma and a terrace was formed. Companied by the breakup of the Tangxian surface, the Baode paleo-lake stopped to deposit fluvial sediment and the river disappeared, which was caused by the uplift of Qingzang movement (phase A).(4) At about 1.2Ma, the Yellow River run through Sanmen Gorges, cut off the Ordos Plateau and then the Jinshan canyon, which connected the Fenwei Basin and the Hetao Basin, was formed. Since then the water system of the middle reaches of the Yellow River was built.(5) At the setting of tectonic uplift, effected by climate and other factors, the river incised and formed the latest terrace at about 1.2 Ma, and formed others at 0.865 Ma, 0.787 Ma, 0.621 Ma, 0.412 Ma, 0.336 Ma, 0.245 Ma, 0.129 Ma, 60 ka, 5ka, respectively. Finally the landform was formed as it appears today.更多还原