【作者】 何忠；

【导师】 黄春长；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2006， 硕士

【摘要】 本文对淮河上游禹州市扒村一个典型的全新世黄土-土壤剖面进行了高分辨率研究。通过详细的野外观察、采样和室内实验分析相结合的方法,获得了该黄土-土壤剖面的磁化率、粒度等实验数据;分析论证了各项参数指标与黄土-土壤沉积环境演变的关系及其所反映的沉积特征和沉积环境,重点进行了粒度机械组成及粒度参数(如频率曲线、累积频率曲线、正态概率累积频率曲线、粒度中值、平均值、偏度、标准离差、峰态等参数指标)的分析;对比黄土高原地区陇东XJN剖面、关中盆地西部JYC剖面以及淮河上游地区的新郑PLG剖面,探讨了淮河上游地区黄土.土壤粒度特征与黄土高原地区黄土-土壤粒度特征的异同,揭示了淮河上游地区全新世风成黄土-土壤的物质来源及其沉积动力。分析黄河决溢泛滥频率及豫东、豫北风沙危害及其影响因素,揭示了人类活动对黄河决溢泛滥,对豫东、豫北风沙危害及其对禹州风成黄土-土壤表土层沉积加速的影响。这对于了解淮河上游地区地表物质组成、粉尘来源及其沉积动力系统,反映人类活动对黄土高原土壤侵蚀、黄河下游决溢泛滥和豫东、豫北风沙危害及沙尘暴活动的影响具有重要的现实意义。 经过研究,本文得到如下结论: (1) 通过与黄土高原地区陇东XJN剖面、关中盆地西部JYC剖面以及淮河上游地区的新郑PLG剖面的进行磁化率和粒度数据的对比,发现淮河上游地区的两个剖面远比黄土高原地区两个剖面磁化率要小,粒度要粗且分选性差。表明两地的黄土形成具有不同的沉积动力系统,有不同的物质来源。较之黄土高原地区陇东XJN剖面与关中盆地西部JYC剖面,淮河上游地区新郑PLG剖面和禹州YPC剖面风力搬运物质来源更近,风力更为强劲。 (2) 淮河上游地区黄土物质来源由近源和远源两部分组成。近源物质是主要的,占优势的,其主要来源于黄河决溢泛滥区沉积的沙质和粉沙质物质,其沉积动力主要是地方性的东北风;远源物质是次要的,其来源于西风高空急流所携带的极细粉尘,其组分代表了本地大气粉尘的本底值。东北向的地方性风系、横贯欧亚大陆的高空西风急流,作为淮河上游地区黄土粉尘的搬运介质共同起作用,形成了该地黄土-土壤沉积序列。 黄河自贯通以来,携带大量的黄河中游流域土壤侵蚀的泥沙倾泻到下游平原上,河流比降骤然减小,流速减缓,搬运动力减弱,大量的泥沙堆积于河床中,以致河床越堆越高,成为“悬河”。此后黄河频繁的决溢、改道、泛滥在淮河上游地区形成了大片的冲积扇和泛滥平原,为淮河上游地区黄土的形成提供了近源更多还原

【Abstract】 A representative Holocene loess-soil profile is studied high-resolutionly in this thesis at Pacun , Yuzhou city in the upper reaches of the Huaihe River. Through field observation, sampling and experimenting, a lot of datas of grain-size, magnetic susceptibility at the loess-soil profile are gained. It is analyzed that the connections between the experiment data and sediment environment, sedimentary feature of the deposits. The analysis of mechanical grain-size composition and grain-size parameter is emphasized, including frequency curves, accumulative frequency curves, normal probability accumulative frequency curves, grain-size median, mean size, standard deviation, skewness, kurtosis. By discussing the similarity and distinction between the loess-soil substance in the upper reaches of the Huaihe River and that in the Loess Plateau, it is revealed that the source of loess-soil substance and the depositional dynamics of loess-soil in the upper reaches of the Huaihe River. Analyzed the frequency of the burst of the Yellow River, the sand damage of the northern and eastern of Henan and their influential factors, it is revealed that the human activity had greatly affected the burst of the Yellow River, the sand damage of the northern and eastern of Henan and the acceleration of the depositional ratio of the TS in Yuzhou. These have importantly actual significances to acquaint the substance composition, pedogenic change, Holocene loess sediment environment changes, and the depositional dynamics of the Yuzhou, these also have importantly actual significances to reflect the affection to soil erosion of the Loess Plateau, the burst of the Yellow River, the sand damage of the northern and eastern of Henan, and the sand storm by human activities. According to study, the thesis draws the following conclusions: (1) By comparison of the magnetic susceptibility and grain size of loess-soil profile in the Holocene among Yuzhou YPC profile, Longdong XJN profile and the JYC profile which is in the Guanzhong Basin, it is found that the magnetic susceptibility of loess-soil profile sequences in the upper reaches of the Huaihe River was much lower, the grain size was much thicker, and the separation is worse than those in the Loess Plateau and the Guanzhong Basin. It is represented that there are different substance source and depositional dynamics in the two areas. By contrast of the loess of the LoessPlateau, the substance source of the Upper reaches of the Huaihe River is closer, and the transport wind is stronger.(2) The source of loess-soil substance in the upper reaches of the Huaihe River is composed of both near and distant substance. The near substances are dominant, which are silt and clay deposits of the floodplain by the frequent breaching of dike and route-changing, overflowing of the Yellow River. The main depositional dynamics is the northeaster in the area. The distant substances are minority composition, and it is very thin dust carried by West wind in the upper air. The loess-soil sediment profile was formed by the local wind along NE direct and the west in the upper air.Since the penetration of the Yellow River, with massive silt by the soil erosion in the middle reaches, it pours into the plain of the lower reaches. With the decreasing of the gradient ratio, the mitigation of the velocity ratio, the transport dynamics abate, so massive silt is deposited in the riverbed. The riverbed is rising year after year, even some reaches are higher than the ground. Then it is easy to breach the dike, change the route and overflow the plain with massive silt and clay. The massive deposits provide continual substances, which deposited in the lower reaches of the regional wind mainly by northeaster. The transport dynamics of the loess is similar to the aeolian sand in the plain, and both substances are come from the soil erosion of the Loess Plateau.(3) The forming process of loess in the upper reaches of the Huaihe River is discussed. A large number of silt and clay were deposited in the plain by the frequent breaching of dike and route-changing, overflowing of the Yellow River since Yellow River formed. The dry and loose silt was blow by strong wind along NE direct in winter and spring, formed sandy windstorm, the thicker grain-size was carried by the form jumping and creeping, and the thinner grain was carried by the suspending form and deposited in the place about 20-150km distance beside the region of the silt source. At last, the former formed the sandy soil, but with the physical process, the chemical process and the biological pedogenic process, the latter became the sandy loess by the long-lasting wind blowing.(4) By comparison of the frequency of the burst of the Yellow River, climate change curve, the frequency of sandstorm, and the changes of cultivated areas and population, we found that the land cover and the land use of the middle of the Yellow River have been greatly changed by human activities after the Holocene climatic optimum. With the aggravation of soil erosion, the Yellow River pour more silt into the plain of thelower reaches, causing the higher riverbed, the acceleration of breach and overflow, the expansion of the floodplain, in a word more substance to transport. We also found that because of destroy of the land cover of the sandy land which had been fixed in the lower reaches of the Yellow River, the sand start to move again under the northeast wind, lead to severe soil erosion. All of these provide more sand to transport, lead to more soil erosion and sand storm, and also accelerate the depositional ratio of loess-soil in Yuzhou. So to reduce the soil erosion and the damage of sand storm, first we have to conserve water and soil in the middle of the Yellow River, on the other hand we have to fix the active sand and conserve the land cover of sandy land.更多还原