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1.
中山市地貌特征及发育过程   总被引:1,自引:0,他引:1  
根据调查和样品分析,认为中山市地貌特征是:①南高北低;②层状结构明显;③类型丰富多样。评价了各类地貌的工程地质条件。把地貌发育划分为K-Q3^1基底地貌格局形成、Q3^2-1冲积平原、Q3^2-2古三角洲平原、Q3^3河流下切及高地风化、Q4^1小海湾、Q4^2-1大海湾、Q4^2-2新三角洲平原雏形、Q4^ 3三角洲平原推进等八个阶段。  相似文献   

2.
韩江三角洲地貌发育的新认识   总被引:2,自引:0,他引:2  
韩江三角洲从晚更新世中期开始沉积,经历了Q_3~(2-1)的古冲积扇、Q_3~(2-2)的占三角洲、Q_3~3的风化和新冲积扇、Q_4~1—Q_4~(2-1)的新三角洲、Q_4~(2-2)的贝壳堤和沼泽以及Q_4~3的沙堤-泻湖等六个发育阶段。发育模式为河流冲积扇与三角洲的交替发展。重新划分了三角洲的界线,面积为915.08km~2。划分出二类十亚类地貌类型。  相似文献   

3.
通过野外实地考察地质结构、地貌发育及室内实验的方法,对滇中轿子山地区地貌结构和发育特征进行了分析,对轿子山及其外围山地的喀斯特地貌、古冰川遗迹及冻土地貌进行了研究.结果表明:轿子山地区主要构造形迹为褶皱与断裂,轿子山地区整体地势中部高,向东西两侧呈阶梯状下降,河谷切割较深,相对高差大,区内构造地貌发育,地貌大格局受构造控制明显,构造地貌、玄武岩台地、灾害地貌、第四纪冰川遗迹残广布,古冰川遗迹冻土地貌较为发育.  相似文献   

4.
雁荡山流纹岩地貌景观特征及其形成发育规律   总被引:3,自引:1,他引:2  
流纹岩地貌有其独有的特色和发育规律。本文根据大量的实地调查数据, 对雁荡山流 纹岩地貌景观进行了类型、空间分布规律和时间发育规律的分析研究。研究结果表明: 区域 流纹岩地貌景观可分为2 个大类, 6 个亚类, 16 个类型单元; 受区域断裂构造的控制, 区内 沟谷和岩嶂在平面上的发育延伸主要沿NE、NW 和EW 三个方向; 在新构造运动和岩性差异 的控制下, 区内峰、嶂、瀑在垂向上的分布具有分带性; 区域现代地貌的发育肇始于晚第三 纪区域一级夷平面的分裂解体, 自此以后的区内地貌演化经历了四个不同发育阶段, 每个阶 段的地貌景观组合各具特色。  相似文献   

5.
近20年辽河三角洲地貌演化   总被引:7,自引:1,他引:6  
运用钻探和浅地层探测等最新调查成果,对近20年的辽河三角洲潮流沉积进行了研究.根据不同时期水深地形和卫星影像资料对比分析了现代辽河三角洲潮流地貌变化.现代辽河三角洲的沉积主体位于双台子河口.研究区10 m深度内的地层主要包括:潮滩相、潮道相和浅海相沉积,其下为古三角洲相.潮滩相沉积物以砂和粉砂为主,分选中等,跳跃和悬浮组分各占50%左右:浅海相和潮道相沉积物主要为软弱的粘土质粉砂和粉砂质粘土,以悬浮组分为主.全新世以来至1896年,研究区为古辽河、古大凌河和绕阳河之间的小海湾.1896年,双台子河被人工开挖为分洪河道以来,口门外形成盖州滩等潮滩,并快速发育.1958年,双台子河建闸后,人海径流量和输沙量减小.目前.双台子河口整体处于淤积状态,潮滩面积不断增加,整体向南、西、北3个方向扩展.潮滩最大淤进速率为87~683 m/a,平均淤积速率为0.189 m/a.潮滩东侧局部发生侵蚀,平均侵蚀速率为0.122 m/a.潮道面积缩小,具有向西、向北迁移的趋势,最大迁移速率为48~200m/a.双台子河口地貌发育受径流、海洋动力和人类活动的影响,沉积物的主要来源由双台子河河流输沙演变为潮流和沿岸流输沙.  相似文献   

6.
南极东部拉斯曼丘陵区的地貌   总被引:4,自引:0,他引:4  
李栓科 《地理学报》1995,50(4):368-376
拉斯曼丘陵地处极地永久冻土带,风力作用频繁。各种冰缘过程主宰了现代地貌特征的形成,无冰区历史短暂及南极东部古老结晶地盾的相对稳定性,使风化微弱,并以寒冻风化为主,风力地貌、冰缘地貌、冰川地貌、湖泊地貌、海岸地貌和构造地貌组成本区主要的地貌类型,各种堆积地貌形态均不发育,西部地区地貌形态相对年轻,残存的冰碛物地表分丰特征指标冰盖后退依东北到西南方向进行,海岛、半岛及冰陆过渡带构成该丘陵三个差异明显的  相似文献   

7.
基于20世纪80年代后中国海岸风沙地貌研究的主要发展,总结了包括海岸风沙地貌类型、发育模式、风沙运动、沉积特征、发育演变及海岸风沙防治等中国海岸风沙地貌研究的主要进展,并针对当前研究存在问题提出了包括海岸风蚀地貌调查、风沙地貌形态动力学机制、波浪-海滩-沙丘相互作用、风沙地貌发育演化与全球变化以及海岸风沙资源利用与防治...  相似文献   

8.
邹学勇 《中国沙漠》1990,10(2):43-53
亚热带季风区风沙化土地的风沙地貌特性,与中国北方沙漠化土地的风沙地貌和海岸沙丘均有明显的不同。在深入调查和解剖沙堆沉积构造的基础上,恢复其发育过程,提出各种风沙地貌类型的发育模式。并通过对影响风沙地貌发育的各种因素的分析,提出该区风沙地貌发育的有限性。  相似文献   

9.
广东地质构造特征及其与地貌发育的关系   总被引:3,自引:0,他引:3  
本文从大地构造运动、各构造旋回中形成的地层岩石特征、新构造运动与外力作用结合等与广东地貌发育的关系,阐述了构造运动控制了地貌发育过程,构造形迹构成了地貌的骨架,沉积建造是地貌形成的本底,新构造运动及外力地质作用最终塑造了现代地貌等地貌成因观点。  相似文献   

10.
 河湖相沉积是一种非固结沉积物,是风蚀地貌发育的一种重要地质基础。在塔克拉玛干沙漠中发育在这种沉积物上的风蚀地貌分布非常普遍,但相关研究较少,尚缺乏风蚀地貌发育过程方面的研究。基于野外调查信息和理论分析,结合相关文献,分析了塔克拉玛干沙漠河湖相平原风蚀地貌发育的外营力作用机制。研究结果表明:(1)风蚀地貌发育的外营力作用主要有:风化作用、流水作用、风蚀作用以及重力作用;(2)风蚀作用是风蚀地貌发育的主要外营力,但是风化作用、流水作用和重力作用也发挥着重要的作用,它们的关键作用是形成风蚀突破口,而重力作用和风化作用是促进风蚀地貌后期快速发展的重要作用;(3)各种外营力协同作用和互为条件,它们在风蚀地貌发育的各阶段的重要性不同;(4)沉积层特殊沉积构造和外营力作用共同造成了风蚀地貌形态特征。  相似文献   

11.
华北平原地貌体系与环境演化趋势   总被引:6,自引:0,他引:6  
叶青超 《地理研究》1989,8(3):10-20
本文系统讨论华北平原地貌体系的时空分布,与形成营力的内在联系及其演化历史,宏观评价平原环境演化的趋势。  相似文献   

12.
珠江三角洲生物埋葬群与环境变迁   总被引:6,自引:0,他引:6  
黄镇国  张伟强 《地理学报》1995,50(4):310-323
本文将珠江三角洲第四纪环境与现代环境的生物埋葬群进行对照,重建晚更新世中期和全新世中期的古沉积环境,划分出两期的海侵区、海侵波及区、海侵影响区。并对中更新世海侵期表示存疑。  相似文献   

13.
This study aims to test the effectiveness of the changes detection techniques to determine the evolution of the various geomorphological units identified in Ebro River mouth, in order to establish their evolutionary trends and to explain the changes between 1957 and 2013 years. To evaluate the most significant changes in the Ebro River mouth, the different geomorphological units present in the area were obtained by interpretation of aerial imagery. It has been noted that the period 1957–1984 was more dynamic and intense than the period 1984–2013, indicating a loss of capacity of the processes causing changes, and the shoreline is evolving toward a more stable morphology. It was determined that the most important processes that took place were mainly marine erosion processes and anthropogenic expansion. On the characterization in the entire period studied, it was determined that growth or decrease processes (net change) are as relevant in the region as processes which include location changes (swap). The change analysis methodology allows analyzing the evolution of coastal geomorphology, since it allows the determination and characterization of the principal transitions amongst the identified geomorphological units, and, therefore, to obtain the main processes that dominate the area, which is particularly relevant on highly vulnerable environments, such as coastal deltaic areas.  相似文献   

14.
黄河冲积扇发育研究述评   总被引:1,自引:0,他引:1  
黄河冲积扇是第四纪以来多期沉积建造的冲积扇复合体,它既是来自黄土高原的泥沙强烈堆积的地貌单元,又是历代河流决口改道的地区,也是华夏文明的发源地。在回顾了黄河冲积扇发育的研究历史的基础上,详细介绍了黄河冲积扇的形成时代、地貌类型与沉积速率,形成过程与特点等方向的研究进展,系统地论述了河道变迁、地质构造、气候变化以及人类活动等因素对黄河冲积扇形成的影响作用。并指出目前黄河冲积扇的发育研究中还存在着研究深度不够和时空的广度不完整等问题。史前黄河冲积扇的发育研究将成为今后研究中的难点。  相似文献   

15.
Integration of geomorphology, stratigraphy, sedimentology and morphotectonics in the analysis of the lower Cecina River reach, coastal Tuscany, reveals an undocumented historical channel avulsion. Geomorphological evidence and radiocarbon dating support that, from the Last Glacial Maximum until the end of the 16th century, the Cecina River flowed north of the present course and formed a well-developed cuspate delta. Two concurrent factors, active tectonics as a preparing factor and discharge regime as an activation factor, are thus inferred to have favored the avulsion of Cecina River. Fragmentary archaeological and historical records indicate that the late Holocene Cecina River plain was virtually unpopulated until the latest 16th century. This seems the main reason why high-magnitude hydrological events and prominent river channel avulsions were not reported in historical chronicles. From this perspective, geomorphological data may provide important knowledge and understanding of recent dynamics of environmental change when historical record is lacking or missing.  相似文献   

16.
Variations in the coupling of sediment transfer between different parts of a fluvial catchment, e.g., hillslope to axial stream, can hamper understanding but are an integral part of the geomorphological record. Depositional environments respond to a combination of land use, climate, storms (floods), and autogenic conditioning. The distribution of sediment in the upland landscapes of NW England is out of equilibrium with contemporary climate and geomorphological processes; more a function of peri- and paraglacial mobilisation of glacigenic deposits. Soil and vegetation development after deglaciation have interrupted any progression toward sediment exhaustion with sediment release controlled largely by extrinsic perturbation, with late Holocene anthropogenic activity, climate and extreme hydrological events the likely candidates. This paper presents a new radiocarbon-dated Holocene geomorphological succession for the River Hodder (NW England), alongside evaluating new palaeoecological and geoarchaeological data to discern the impacts of human activity. These data show a late Holocene expansion in human occupation and use of the landscape since the Iron Age (700–0 cal. B.C.), with more substantial changes in the character and intensity of upland land use in the last 1300 years. The geomorphological responses in the uplands were the onset of considerable and widespread hillslope erosion (gullying) and associated alluvial fan development. Interpretation of the regional radiocarbon chronology limits gullying to four, more extensive and aggressive phases after 500 cal. B.C. The downstream alluvial system has responded with considerable valley floor deposition and lateral channel migration that augmented sediment supply by remobilising the existing floodplain terraces and led to the aggradation of a series of inset alluvial terraces. The timing of these changes between states of aggradation and incision in alluvial reaches reflects the increased connectivity between the hillslope and alluvial systems. Aspects of both the regional climate and land use histories are conducive to increasing discharge and sediment flux, but the region wide lowering of erosion thresholds appears a key driver conditioning these sediment-rich conditions and producing a landscape that was more susceptible to erosion under lower magnitude flows.  相似文献   

17.
黄河口近期环境演变与河口治理   总被引:4,自引:0,他引:4  
李广雪  韩业深 《地理学报》1996,51(2):182-189
本文分析了近几年来尾闾河道及河口滨海区实测资料,认为尾闾河道河相关系趋向于转好,河口变化造成的溯源冲淤作用影响范围仅有20几km,并且只有在汛期水流强度较大时,才发生溯源调整作用,非汛期淤积严重。由于河口砂咀向海凸出,三角洲前缘形成强流带,加上波浪作用及异重流发育,河口砂咀延伸速度明显减缓。最后,作者对目前河口治理中存在问题的解决提出了建议,尤其指出不应轻易放弃目前良好的河口行水环境。  相似文献   

18.
高善明 《地理研究》1985,4(1):54-62
本文根据河谷阶地对比,沉积相特征,孢粉组合,石英砂表面微结构组合和14C、古地磁年龄数据,探讨滦河(东部)冲积扇的形成时代、沉积环境和沉积速率,为研究唐山山前平原地下水储存条件提供一些论据。  相似文献   

19.
The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area.This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating.In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations.Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.  相似文献   

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