【作者】 郭力宇；

【导师】 甘枝茂；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2002， 博士

【摘要】 陕北黄土高原分布于“北山”之北，长城沿线之南，是中国黄土高原地貌景观的重要组成部分。在长期的研究和调查过程中，发现陕北黄土高原在南北纵向上存在明显的黄土地貌分异现象，即由南向北，大致依次为洛川黄土塬(广义)地貌、延安—安塞黄土梁状(为主)丘陵沟壑地貌、绥德—子洲黄土峁状(为主)沟壑地貌。 这种黄土地貌格局及变化趋势传统认为是与其下伏基岩地层古样式形态具有承袭性的耦合关系。但在野外调查及同其他学者交流中发现两者并非总体对应一致，显示出陕北黄土高原南部黄土塬基底起伏相对较大，北部黄土梁状(为主)丘陵沟壑区及黄土峁状(为主)丘陵沟壑区基底相对平坦的特征。为此，对传统认识提出质疑，并通过基底地层古样式形态模拟的途径，采用野外调查与综合研究的方法，以及GPS、GIS新技术手段的运用对其进行综合、系统的分析论证。该课题的研究和开展，对人们正确认识陕北黄土地貌的发展演化与形成具有十分重要的意义。 同时，陕北黄土高原是一个水土流失严重的地区。过去的研究主要侧重于水土流失区域宏观性认识的总结及在局部或采用实验手段对其外部因素影响机理研究模拟的两大方面。然而，地质构造是影响水土流失的重要因素之一，它对物源区水土流失的重要方式之一——黄土体崩解及水土物质输移通道(河沟体系)等的产生与发展均有重要影响作用。特别是陕北黄土高原地区的基底地层褶皱构造、基底节理构造及黄土节理构造对水土流失、水系的产生和演变有重要影响。因此对它进行研究能够深化对陕北黄土高原水土流失形成及特点的认识。 在野外，以代表调查区和路线调查相结合的方法，利用GPS12XC型手提式定位仪采集基底高程数据，实地观察基底地层产态变化规律和特征，观察黄土地貌、黄土崩塌、水系展布及土壤侵蚀等与地质构造之间的关系；在室内主要进行综合分析与对比，利用GIS系统的Mapinfo 6.5软件对采集数据模拟分析，并将认识成果与其他专家学者进行交流和探讨，从而论证和揭示陕北黄土地貌南北纵向分异与基底古样式关系特征及水土流失与构造因素之间的内在规律。在大量的野外调查及系统分析论证的基础上获得以下主要成果： 1．首次依据陕北黄土下覆基底地层构造、古地形南北纵向区域变化特征的研 究结果，提出并论证了陕北黄土地貌瞰、梁、赤）与基底古样式之间总体存在看 非耦合关系的新认识。具体地讲，陕北高原南部的洛）11黄土源，黄上层顶部相对 平坦，地貌类型以黄土源为主格调，而其下伏基岩地层诏皱相对发育，古地势起 伏相对较大：陕北高原中部的延安一安塞黄土梁状（为主）丘陵沟壑区，黄土层 顶部起伏相对增大，地貌类型以黄土梁为主格调，而其下伏基岩地层槽皱程度趋 弱，地层较平缓，古地势起伏相对降低；陕北高原北部的绥德一子洲黄土赤状（为 主）丘陵沟壑区，黄土层顶部起伏度相对最大，地貌类型以黄上赤为主格调，而 其下伏基底地层以平缓为特征，古地势起伏强度亦相对较低。并进一步论证了陕 北黄土高原地貌的塑造是以外力侵蚀等因素为主导所形成。外力侵蚀是历史性 的，是长期性的。 2．首次利用多因素评判地势起伏的方法，利用模糊综合评判模型对陕北黄上 高原地貌与其基底古样式的非耦合关系进行分析，提出该非耦合关系为较好级 别，其隶属度为0．3308。 3、依据黄土圾区黄土崩塌的形式、产生部位及受控固素的特点，首次将黄土 崩塌划分为两种类型：其一为单面崩塌，其二为栅格崩塌；并探讨了不同构造类 型与黄土崩塌之间的内在联系。 4．分析了陕北黄土高原不同级别水系与构造的关系。依据各自受控构造固子 的不同，得出I级南北干流（洛河）受控于区域偷斜构造；11级近东西向河谷（沟） 受控于黄土下覆基岩节理构造；Ill级支毛沟受控于黄土节理构造的新认识。 5．经过分析和研究，认为黄土圾区是以厚层黄上体为载体的特殊地貌景观， 其自身沟道发展演化具有特殊性，以鱼鳞状黄土崩塌为主的高角度陡倾河谷的加 宽发展方式为特点，构成洛）11＃式河谷发展演化模式。 6、根据黄土源区地貌演化关系，将其地貌划分为三部分：黄土“源区”，沟 壑区及过渡区。其中过渡区是溯源侵蚀及沟头侧蚀加宽的活跃区，是黄土“圾区” 向沟壑区转换的关键地段。指出过渡区是水土流式强烈区，是治理的重点地段。更多还原

【Abstract】 Shaanbei Loess Plateau, which is located in north Shaanxi from Beishan Mountain to Great Wall, is one of the landscapes of China Loess Plateau. There is a evolutional phenomenon to have been recognized in Shaanbei Loess Plateau from South to North .That is Luochuan district with the Loess Yuan (Platform Land) in south . Yan’an-An’sai district with the Loess Liang ( Ridges) mainly in middle and Shunde-Mizhi district with the Loess Mao (Rounded knolls) mainly in North .This frame and tendency is got and thought to coincide with the styles of their bedrock traditionalh?called conformability. But the conflict between them was appeared during our research in field and the discussion with others. It is followed that the former with the rolling bedrock, the mid with mild bedrock and the latter with the stable bedrock relatively. The conflict between two conclusion above arise, what relationship between loess landforms and their bedrock exist? This is related to other important issues, such as erosion protection, origin of loess landforms. development of local economy, and so on. With the simulating of the paleo-shape of the bedrock at office, research in field and application of GPS and GIS, The project has been studied.Meanwhile, Shaanbei loess Plateau is one of serious erosion. Usually .the summarization of erosion regulation and the mechanism outer faction in Lab are focused. The geological factors are important besides them, which are related to the loess landslide and evolution of gullies, specially for bedrock folds, bedrock joints and loess joints.In field, the data of the bedrock elevation in the three sheets combined with the research from south to north lively were got by GPS12XLC pocket locator, the type and its evolution of bedrock, loess landslides and distribution of hydrographical net were explored too.At office, the synthetic analysis and contrast were used including the simulating analysis about the data by Mapinfo 6.5, Software of GIS, discussion and communicationwith experts, in order to demonstrate and reveal the rules between the loess landforms and its pale bedrock landforms and the impact of structure on erosion interiorly in Shaan bei.After a lot of research and study, the following results have been attained:1. The unconformability between the loess landform of Shaanbei Loess Plateau and its bedrock shape was pointed out first after the full demonstration. The top of loess formation of the south part in Shaanbei is flat which likes "Platform", the shape of the bedrock is rolling that likes Ridge , and the bedrock bended to fold. The top of loess formation of the mid-part in shaanbei is rolling ,but the shape of the bedrock below begins to get flat, the top of loess formation of the north part in Shaanbei, loess Mao district, is much more rolling among them, however, its shape of the bedrock below is the flattest relatively likes the Platform shape of loess formation in south. From that new conclusion, we know the form of loess landform was built by erosion result from outside forces, which is historical and long-term.2. The unconformability between two sides has been analysed and belongs to better-level, the degree of subordination is 0.3308 through the fuzzy synthetic judgement on multi-factors.3. The loess landslide has been grouped to two types, one is single-side landslide the other is grid landslide. According to their styles, locations occurred and other controlling geological factors.4. There are different level and directional gullies and rivers. According to different controlling geological factors, they could be classified to three groups. And we pointed out the evolution of the first group which is the biggest level from north to south basically is limited by Shaanbei syncline structure, the evolution of second group which is the mid-level form east to west or from west to east basically is limited by the bedrock joints, the evolution of the last one,which belongs to small level is limited by loess joints.5. During the explorer, we know更多还原