Knowledge Resource Center for Ecological Environment in Arid Area
| 黄河宁蒙河段粗沙重矿特征及其指示意义 | |
| 其他题名 | Heavy mineral characteristics and its indicative significance of coarse sediment in the Ningxia-Inner Mongolia River |
| 石晓萌 | |
| 出版年 | 2013 |
| 学位类型 | 硕士 |
| 导师 | 拓万全 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 黄河宁蒙河段处在黄河上游的最下段，上起宁夏石嘴山市，下迄内蒙古托克托县，中间穿越乌兰布和沙漠与库布齐沙漠，全长约673公里，属于典型的沙漠河流。近几十年来，由于受气候变化、沙漠扩张、人口增加、耕地扩大、用水过度等多因素的影响，该 河段河床淤积抬高，河槽萎缩，开始出现类似黄河下游的“悬河”问题，并有发展成“二级悬河”的趋势，黄河生命安全受到严重威胁。由于该段河道河床淤积，河床的行洪、行凌能力降低，洪灾、凌灾频繁发生，严重威胁人民生命财产安全，制约着经济的可持续发展，已引起国家高度重视和科技界的广泛关注。研究该段河道淤积泥沙的来源及其入黄过程，对于减缓该河段洪凌灾害，维护黄河健康，具有重要意义。 本文首先通过对黄河宁蒙河段河道27个样品点的粗泥沙重矿物特征进行分析研究，表明该河段粗泥沙重矿物以性质不稳定的角闪石、较稳定的绿帘石、赤褐铁矿为主要矿物，稳定矿物除刚玉、钛铁矿外，锆石、金红石、黄铁矿、电气石含量极少。稳定系数法计算结果表明在河东沙地河段、乌兰布和沙漠河段以及十大孔兑河段之间稳定系数最低，几乎接近于0，说明在这三个地区河道粗沙源于附近沙源不同形式的汇入。本研究区ZTR指数极低，平均含量只有0.0071，说明黄河宁蒙河段泥沙重矿物成熟度低，淤积的泥沙并未经过长途的搬运堆积，而是来自当地沙源的汇入。相关系数法给出了三种不同性质的矿物组合类型，分别指示了不同的母岩类型和物源环境。 通过以上研究，初步取得了以下结论： 1. 河道粗泥沙重矿物以不稳定的角闪石、辉石，较不稳定的绿帘石、赤褐铁矿为主要矿物，稳定矿物除刚玉外，锆石、金红石、电气石等含量都极低甚至没有。不稳定矿物含量高，说明黄河宁蒙河段泥沙的来源并非来自上游河段长距离的搬运，而很可能来自河道附近沙源的汇入。 2. 低的稳定系数值和低的ZTR指数值，表明宁蒙河段粗泥沙没有经过长途的河水搬运，物源并非来自上游段，而是来河道附近的沙源。在经度106.5°E～107.25°E，107.5°E～108.25°E以及110.25°E～110.5°E之间稳定系数最低，几乎接近于0。可能的原因为：①河东沙地的粗沙通过塌岸、风沙流、以及沙丘前移的方式进入黄河，导致该地区河道泥沙淤积；②乌兰布和沙漠的风沙在西风、西北风的吹动下，直接进入黄河；③库不齐沙漠的流沙于风季带入沟内，洪水季节携带风沙进入黄河。 3. 相关系数分析研究重矿物组合，划分了三种不同类型性质的重矿物组合，分别是锆石、钛铁矿、黄铁矿组合：这一组合重矿物含量很少，说明宁蒙河道粗泥沙部分来源于花岗岩层；角闪石、磷灰石组合指示沙源与前者不同，且角闪石含量较高表明河道粗泥沙来源于附近地区；辉石、赤褐铁矿组合指示气候干旱、水体较浅的氧化环境，结合角闪石、磷灰石组合的指示作用，表明宁蒙河道粗泥沙主要来源于当地的沙漠粗沙。 |
| 英文摘要 | The Yellow River flows through an extensive, aeolian Inner Mongolian plateau and extends from Shizuishan, Nixia Province to Hekouzhen, Inner Mongolia Province with a total length of 673 km. This valley lies in the end of the upper reach of the Yellow River and is known locally as the Ningxia-Inner Mongolian Reach of the Yellow River, bordered by the Ulan Buh desert and KoBQ desert, belonging to a typical desert river. In recent decades, due to the influence of many factors such as climate changes, desert expansion, population growth, arable land expansion and water overuse, the bed elevation of the Ningxia-Inner Mongolian Reach has been rising and the river channel has been shrinking. The problem of “Hang River” as the lower river of the Yellow River is beginning to appear in this reach and take on the trend of forming the “Secondary Hang River”, the life of the Yellow River is under threat. Sediment siltation in the Ningxia-Inner Mongolian reach usually results in riverbed elevation, the loss of flood delivery capacity of river channels. Thus, outburst flood disasters are often occur in this region, which have claimed thousands of human lives and resulted in tremendous losses of property, and to a large extent, restrict the sustainable development of economy and society, and this have been attracted by our country and the scientific community. Study on the source and siltation process of the riverbed sediment in the Ningxia-Inner Mongolian Reach of the Yellow River has great significance in reducing the flood disasters and keeping the health of the Yellow River. Heavy mineral wear erosion with a strong stability, and is able to retain most of the information and characteristics of its parent rock, and is therefore being used for source analysis. In this paper, 27 heavy mineral samples of sediment in the Ningxia-Inner Mongolia reach were conducted and analyzed. The result shows that heavy mineral in this reach is rich in amphibole, which is by nature unstable, as well as limonite and epidote which are relatively stable. Stable mineral such as zircon, rutile, yellow iron ore and tourmaline content is extremely low, except corundum and ilmenite. Stability coefficient curve shows that it is the lowest in Hedong sandy land reach, Wulanbuhe desert reach and Shidakongdui reach, and almost close to zero. It indicates that in these three sections of the Yellow River, sediments originate from the nearby sand sources imported by different forms. ZTR index in this research area is extremely low, with the average content only 0.0071, illustrating an extremely lower heavy mineral maturity in the Ningxia-Inner Mongolia reach of Yellow River. The correlation coefficient gives three different types of mineral assemblages, indicating different types of parent rock and source environment. |
| 中文关键词 | 黄河 ; 宁蒙河段 ; 粗泥沙 ; 重矿物特征 ; 指示意义 |
| 英文关键词 | Yellow River Ningxia-Inner Mongolia River coarse sediment |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287237 |
| 推荐引用方式 GB/T 7714 | 石晓萌. 黄河宁蒙河段粗沙重矿特征及其指示意义[D]. 中国科学院大学,2013. |
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