龙羊峡—刘家峡河段巨型滑坡堵河事件与黄河演化之间的关系

发布时间：2018-07-18 09:33

【摘要】：黄河龙羊峡-刘家峡位于青藏高原的东北缘,地处地壳抬升强烈的青藏高原和相对抬升的黄土高原之间的过渡地带。构造上研究区处于西秦岭和南祁连块体接合部,区域构造复杂,同时也位于东亚季风、西南季风及西风带的交汇部位,因此独特的地理位置使得黄河上游对高原隆升和全球气候的变化响应极为敏感。在此特殊的区域构造、三大气流系统交汇的背景条件下晚更新世以来研究区黄河谷地巨型滑坡(方量大于1×108 m3)密集发育,并且多数滑坡曾堵塞黄河河道形成堰塞湖。黄河谷地巨型滑坡堵塞黄河,具有规模大,分布密度高,堵塞黄河时间长,滑体保留时间久的特征,给人民生命财产造成威胁,同时也对黄河上游谷地带来巨大的地貌效应。堰塞湖的存在使得堰塞坝上下游一定范围内形成一个独特有别于整个黄河流域的局部沉积环境,这一局部的河谷沉积环境至今还未进行系统研究。因此,论文在对研究区龙羊峡-刘家峡段黄河阶地尤其是与巨型滑坡或堰塞湖有孕生关系的(低)阶地进行地貌研究和测年的基础上,对循化盆地的戈隆布滑坡、尖扎盆地的德恒隆和锁子滑坡、贵德盆地黄河支流尕让河岸坡的阿什贡滑坡的滑坡特征、形成机制、对应堰塞湖规模及其与黄河阶地等的地貌关系进行分析,研究巨型滑坡堵河事件与黄河演化之间的关系,主要取得以下认识和研究成果:(1)结合已有研究基础,论文总结出研究区黄河河谷构造运动史及其相应拔河高度。论文还对上述三个盆地内12个黄河阶地剖面尤其是与堰塞湖有孕生关系的阶地剖面进行地层学研究和16个光释光样品进行年代学研究,这一工作将填补研究区尤其是尖扎和循化盆地很多低阶地无测年数据的空白。并初步总结出黄河上游河谷岸坡发育特征:所有低阶地(六级以下)的堆积形成年代过程都发生在晚更新世以来冰期或者冰期向间冰阶过渡期和高原季风减缓时期。因此研究区所有低阶地的堆积形成主要受气候控制,但也对区域构造积极做出响应,主要体现在阶地的平均下切速率与GPS构造抬升速率基本一致。(2)论文对研究区5个典型巨型堵河滑坡进行了野外地质调查,采集了12个光释光样品进行年代学研究,并对堰塞湖范围和溃坝洪峰流量进行了计算,结合前人文献和本人硕士期间对研究区做过的堵河滑坡年代数据,以及区域构造背景和晚更新世古气候资料,本文统计分析认为研究区晚更新以来巨型滑坡主要集中在5个时期发育,分别对应于深海氧同位素五阶段、八万年左右、三阶段、冰消期和全新世。除去八万年时期的巨型滑坡与青藏高原东北缘8万年构造期有关,其他阶段时期发育的滑坡在区域构造背景下都应与暖湿气候有关。发育于深海氧同位素五阶段、三阶段和全新世的巨型滑坡群主要与高原季风增强带来的强降水有关,冰消期发育的滑坡应与冰雪融水以及高原季风增强有关。(3)在综合滑坡发生年代和阶地堆积形成年代基础上,分析了在地层和时间序列上阶地、滑坡和堰塞湖受气候控制的作用:研究区集中发育在间冰期/间冰阶的巨型滑坡都紧随阶地堆积形成之后发育,并且滑坡体堆积物或堰塞湖湖相沉积大部分都覆盖在冰期/冰期-间冰期过渡时期堆积形成的阶地之上。滑坡和阶地主要受晚更新世冰期-间冰阶旋回和高原季风强度的控制。但其中也有个别时期的滑坡和阶地可能受区域构造的控制,比如8万年时期的滑坡和阶地。本文认为滑坡堵河、堰塞湖溃坝形成阶地、新一轮滑坡再堵河这一地质演化过程受气候影响具有周期性。(4)探讨了巨型堵河滑坡/古堰塞湖形成与河谷沉积之间的地貌关系,主要表现为:滑坡发生后改变河道上下游的纵坡降比、河岸形态,甚至迫使水系改道;溃坝后流水强烈下切诱发老滑坡复活;河谷的侵蚀堆积历史对滑坡的发育表现出空间分带性和时间阶段性;堰塞湖形成导致其上下游的沉积侵蚀环境发生变化以及其对下游文明带来的潜在威胁等。
[Abstract]:Located in the northeastern margin of the Qinghai Tibet Plateau, Longyangxia - Liujiaxia, the Yellow River, is located in the transition zone between the uplift of the Qinghai Tibet Plateau and the relatively uplifting Loess Plateau. The tectonic area is located in the junction of the West Qinling Mountains and South Qilian blocks, with complex regional structures, and at the same time the intersection of the East Asian monsoon, the southwest monsoon and the west wind zone. This unique geographical location makes the upper reaches of the Yellow River highly sensitive to the uplift of the plateau and the global climate change. In this special regional structure and the intersection of the three large airflow systems, the giant landslides (more than 1 x 108 m3) in the the Yellow River Valley in the study area since the late Pleistocene have been densely developed, and most of the landslides have blocked the the Yellow River river shape. The huge landslides in the Yellow River Valley, which block the Yellow River, have large scale, high density, long time of blocking the Yellow River and long retention of the slide body, which threaten the people's life and property, and have a huge geomorphic effect on the upper reaches of the Yellow River. The deposit of the weir Lake in a certain range of the dam is formed in a certain range. The local sedimentary environment that is unique to the whole the Yellow River basin has not been systematically studied so far. Therefore, on the basis of the geomorphological study and dating of the the Yellow River terrace in the Longyangxia Liujiaxia section of the study area, especially the geomorphic (low) terrace related to the giant landslides or the dammed lakes, the paper is on the Xunhua basin. The landslides landslide, the Jianzha basin's de Heng Long and the lock son landslide, the the Yellow River tributary of the Guide basin, the Ashe Gong landslide of the riverside slope of the Guide basin, the landslide characteristics, the formation mechanism, the relationship between the scale of the barrier lake and the landform of the the Yellow River terrace, and the relationship between the huge landslides and the evolution of the the Yellow River The achievements are as follows: (1) combining with the existing research foundation, the paper summarizes the history of the tectonic movement of the the Yellow River River Valley and its corresponding tug of war in the study area. The paper also studies the stratigraphic study and the chronological study of the 16 light release light samples of 12 terrace sections in the three basins, especially the terrace sections that have a pregnant relationship with the barrier lake. This work will fill in the blanks of a number of low terrace data in the Jianzha and Xunhua basins, especially in the Jianzha and Xunhua basins, and preliminarily summarize the characteristics of the development of the river valley slope in the upper reaches of the the Yellow River. Therefore, the accumulation of all lower terraces in the study area is mainly controlled by climate, but it also actively responds to the regional structure, which is mainly reflected in the average cutting rate of the terrace and the GPS tectonic uplift rate. (2) the paper has conducted field geological investigations on 5 typical giant landslides in the study area, and collected 12 light release patterns. The article carries out the chronological study, and calculates the flood peak flow of the barrier lake area and the dam break, combined with the previous literature and the data of the landslide age of the river plugging in the study area, and the regional tectonic setting and the late Pleistocene paleoclimate data. The statistical analysis shows that the giant landslides since the late renewal of the study area are mainly concentrated in 5. The development of the period is corresponding to the five stage of deep sea oxygen isotope, eighty thousand years or so, the three stage, the glacial period and the Holocene. It is related to the 80 thousand year tectonic period of the northeast margin of the Qinghai Tibet Plateau by the eighty thousand years. The other stages of the landslides developed in the other stages should be related to the warm and wet climate in the regional tectonic setting. The massive landslides in the three stage and the Holocene are mainly related to the strong precipitation caused by the enhancement of the plateau monsoon. The landslides developed during the deglaciation period should be related to the ice and snow melt water and the enhancement of the plateau monsoon. (3) on the basis of the age and terrace accumulation age of the comprehensive landslides, the terraces, landslides and weirs on the strata and time series are analyzed. The effect of the lake is controlled by the climate: the giant landslides in the interglacial / interglacial stages developed in the study area after the accumulation of terraces, and the landslides and lacustrine lacustrine deposits mostly covered the stage of the glacial / Glacial interglacial transition period. The landslides and terraces were mainly in the late Pleistocene. The interglacial interglacial cycle and the intensity of the plateau monsoon are controlled, but there are also some landslides and terraces that may be controlled by regional structures, such as landslides and terraces in the 80 thousand year period. In this paper, we think that the landslide and the dam break the river, the dam break the terrace, and the new landslides and then the river plugging the river, the geological evolution process is periodically influenced by the climate. (4) the geomorphologic relation between the formation of the giant plugging River landslides / the ancient barrier lake formation and the valley deposition is discussed, mainly as follows: after the landslide occurs, the longitudinal gradient ratio of the upper and lower reaches of the river is changed, the riverbank form and even the water system are forced to change. After the dam break, the flowing water is strongly cut down to induce the resurrection of the old landslides, and the erosion accumulation history of the Valley shows the space for the development of the landslide. The formation of barrier lake leads to the change of sedimentary environment and its potential threat to downstream civilization.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P642.22

【相似文献】