【作者】 夏凯生；

【导师】 袁道先；

【作者基本信息】 西南大学 ， 自然地理学， 2011， 博士

【摘要】 我国的岩溶区面积广大,分布广泛,岩溶地貌类型多种多样。碳酸盐岩的分布面积计(含埋藏在非可溶岩之下者),可达3.46×106km2,约占国土面积的1/3；而且类型多种多样,总体上说,可以分为四大类型：南方湿润热带亚热带岩溶、干旱半干旱区岩溶、温带半湿润区岩溶和西部高原高山岩溶。我国的岩溶地貌研究具有世界意义,与世界其他地区岩溶区相比,我国岩溶形态丰富多彩、个性鲜明。这是因为我国岩溶地貌,发育有独特的优势,即中国大陆碳酸盐岩古老坚硬、新生代以来大幅度抬升、未受末次冰期大陆冰盖的刨蚀破坏、以及季风气候水热配套(夏湿冬干)等四个条件,使得各个地质时期,尤其是新生代以来发育的岩溶形态保存完好,因而具有较长的、连续的岩溶发育的历史记录。中国南方热带、亚热带岩溶地貌被称为大陆热带-亚热带岩溶地貌的“博物馆和教科书”,在中国岩溶地貌研究中有重要地位。2007年7月,中国南方岩溶被联合国教科文组织正式列入《世界自然遗产名录》,乌江下游岩溶地貌作为亚热带峡谷岩溶地貌的代表也被列入。乌江下游岩溶地貌的研究对中国南方岩溶中山峡谷岩溶地貌的研究有十分重要的意义,但是现在的研究还很薄弱。形态学的研究主要应用了岩溶形态组合的研究方法,应用该方法可以避免“异质同相”在岩溶地貌形态研究中所引起的混乱。我们应用岩溶形态组合对乌江下游不同地貌面的典型地点的岩溶形态组合特征进行了探讨,并且和岩溶地貌形态发育阶段结合起来,探讨其演化过程。沉积形态的研究是研究岩溶地貌演化的关键,把溶蚀形态和沉积形态相结合进行研究,通过对典型地点沉积物特征的研究来探讨岩溶环境的演化过程是本研究的一项重要内容。对于岩溶地貌发育控制因素的分析,我们运用岩溶动力系统理论,把岩溶地貌形成原因研究放到岩石圈、水圈、生物圈、大气圈相互作用中去研究,探讨内外力作用对本区岩溶地貌形态发育演化的影响。本研究得出如下结论：(1)本地区岩溶地貌十分发育,具有独特的亚热带岩溶中山峡谷特点,以峰丛洼地(谷地)、大型漏斗(天坑)、岩溶峡谷、天生桥等为代表的地表岩溶和以大型溶洞和丰富的洞穴次生化学沉积为代表的地下岩溶最为普遍,独具特色。(2)不同地貌面上岩溶形态组合是岩溶地貌不同发育阶段的产物：鄂西期夷平面分布在海拔1700～2000m的高分水岭地区,形态组合特征是低矮的峰丛和平坝、大的多边形、浅碟形洼地相组合,石峰形态浑圆,峰与峰之间的疏离度高,平均为500m以上；溶洞不多,发育规模不大,沉积形态为红粘土,其岩溶形态组合反映了老年期岩溶地貌发育的特点,其形成在古近纪至新近纪初。山原期地面分布在海拔1200～1500m的地区,主要表现为高大的峰丛和大型洼地结合的岩溶台面。峰丛与洼地、岩溶台面之间的相对高差可达25～30m左右,峰与峰之间疏离程度变小,一般在300～400m；岩溶洞穴十分发育,有较丰富的次生沉积物。沉积物为红粘土,发育有铁质风化壳,总体上为壮年期地面特点。剥蚀面分布在海拔500～800m地区,以峰丛-槽谷、谷地为主,比高为60～100m,峰与峰之间疏离程度极小,一般在250m以下,基座紧密相连,石峰形态不太典型,顶部平坦,保留原始地貌面的特点,沉积物以黄色石灰土为主,体现为青年期岩溶地貌发育阶段的特点。(3)岩溶地貌发育的受岩性、构造、气候、土壤、水动力等多种因素的影响,本区岩溶地貌发育的主导因素为新构造运动、水动力条件和气候；通过对典型地点岩溶作用强度的研究发现：在现在气候条件下,鄂西期山地的岩溶作用比较弱,而盆地期地面岩溶作用比较强,说明鄂西期岩溶形态组合有古老性的特点,为第三纪末干燥气候形成的；盆地期剥蚀面之所以为青年期地面,和其发育历史较短有关。由于受到新构造运动的影响,本区岩溶形态组合呈现出多代性的特点,岩溶峡谷和夷平面交替出现,同时,夷平面受到后期的改造,由于强度不同,在不同地区呈现出不同的特点：在远离现代排水基面的流域分水岭地区,新构造运动影响较小,地面完整性较好,岩溶地貌以峰丛洼地为主,地貌面发育以横向发育为主。乌江及主要支流河谷地带受新构造影响很大,因溯源侵蚀,普遍发育峡谷地貌,在河间地块因受新构造运动地貌影响较大,地面表现为锥状岩溶峰丛洼地和岩溶谷地景观。(4)乌江下游岩溶地貌的形成,经历了鄂西期、山原期、盆地期和峡谷期地貌演化阶段,并形成鄂西期、山原期夷平面、盆地期剥蚀面和深切峡谷。通过对乌江下游岩溶地貌形态、发育和演化的研究,我们对亚热带岩溶峡谷的形态、发育和过程有了较为清楚的认识,因此本研究对长江三峡形成演化的研究有借鉴意义。同时,本地区的岩溶地貌发育深受新构造运动和水动力条件的影响,河流侵蚀和溶蚀作用叠加在一起,使本区的岩溶地貌发育强度增大,这既可以形成了景色迷人的乌江峡谷,又使本区生态环境及其脆弱,水旱灾害、水土流失、石漠化、地面塌陷等灾害频频出现；我们也注意到不同地区岩溶作用强度和方式不同,不同地貌面和岩溶峡谷区在进行土地利用、水资源开发和环境保护方面时必须要注意到不同地区的不同特点,因地制宜。更多还原

【Abstract】 There are large,widely distributed karst areas and variety of karst landforms.in China. the area of carbonate rocks (including buried below non-soluble rock), is 3.46 x 106km2, about 1/3 of land area of China. and there are variety of types karst, generally speaking, these types can be divided into four types:subtropical karst of South China, arid and semiarid karst of North China and temperate semihumid karst of northeast China Alpine karst on Qinghai-Tibet Plateau.There is international significance on the work of Karst landform in China. Compared with the Karst areas elsewhere in the world, the Karst forms of China is more colorful, distinctive. because the development of karst landforms in China has mre unique advantages.that is to say:the backgrounds for the development of karst in China’s mainland are characterized by:i,hard,compact carbonate rocks ii,strong Cenozoic uplift; iii,heat-moisture matching monsoon climate;iv, without scouring actions of continental ice sheet of the Last Glaciation. All these backgrounds make the karst forms of China have preserved before Traissic; and have a long, continuous history of karst development.The subtropical karst of South China has been known as the continental tropical-subtropical karst "museums and textbooks, so it is important in the work on the karst geomorphology of China. In July 2007, the south China Karst had been officially recorded in UNESCO’s "World Natural Heritage List " by UNESCO, and the karst valley of lower reaches of Wujiang had also been recorded in this list as the representative of the subtropical karst valley.The study of development and evolution of karst landform of the of lower reaches of Wujiang is very important that we how know karst features of subtropical gorge regions is developed and evolved。but now the study is still very weak.The study method of Karst feature complex is be applied in the Karst morphology study of the of lower reaches of Wujiang, and this method can avoid the confusion that the same form of different innate character brought about in the Karst morphology study. In order to explore the evolution process of this area, the characteristic of Karst feature complex typical locations of the steeped landforms will be studied and will be combined to the development stage of karst landforms.The key research of the evolution of karst landforms is to study the characteristic of depositional forms. The combining analysis of the dissolutional and depositional forms, we can know karst landforms evolution process of this area through the study of the characteristic of depositional forms of typical place.On the study of the controlling factor of the development of karst landform, this study apply Karst Dynamics system(KDS) to explore causes of karst landforms evolution.these causes can link with interaction of lithosphere, hydrosphere, biosphere and atmosphere, so the development and evolution of karst forms can be controled by internal and external forces.Conclusions as the following are drawn:(1)There is a large scale of karsts geomorphology and possesses a unique subtropical mid-mountain karst gorge characteristic,enriched abundant surface karst represented by cone fengcong-depression, giant doline, gorge, natural bridge, and underground karst represented by giant caves and secondary speleothems. It perfectly display typical multitype and multilevel karst features of subtropical deep incising gorge regions.(2)The Karst feature complexs on the different topographic surface are products of different developmental stages of karst landform. Exi Phase (Higher Plateau Phase) in the three gorges areas. kept in the watershed regions of 1700m to 2000m above sea level, At present the Karst feature complexs of earth surface of this phase are represented by combination low peaks, Karst platform with large polygons and Shallow dish depressions.The feature of the peaks is rounded and the distancing between two peaks is high,about 500m;there are little caves, who are small; there developed red clay on karst platform. all these reflects a elderly period of karsts development period. and formed e from the Paleogene to the early stage of neogene, The lower planation surface of 1200～1500m above sea level, the feature of earth surface of this phase is tall peaks and large depressions, the height between peak and the table is 25～35m or so, and distancing become smaller and is 300-400m. there developed karst caves and abundan secondary deposits. are be found in it. Its surface deposits is red soil, in some places,weathering crust of iron was found;this reflects a maturity period of karsts development period. The erosion surface of 500-800m above sea level, the marked feature is Peaks-trough valley, valley; the height between peak and depression is 25～35m or so, and distancing become smallest and is only 250m. the peak,s bases are closely linked, the features of peakis not the typical, the top is fat and Preserve the original characteristics of geomorphic surface; Its surface deposits is yellow soil. All this reflects young period karsts development period.(3)All the karst features of lower reaches of Wujiang, are the reflection of its special lithological, Stratigraphical, tectonical, topographical, hydrodynamic conditions,climatic background, neotectonics movement,as well as long term karstification. the dominant factors of development of karst landforms are neotectonics movement. hydrodynamic conditions and climatic background.To study on karstification intensity and its variation under different geological settings, we come to conclusion:under previous climatic conditions, the karstification intensity on Exi earth surface is weaker than Pengdi’s, this indicate the Karst feature complexs of Exi have developed very long time and its form can be attribute to the latest period Tertiary dry Climatic conditions; the karst features of Pengdi’s surface is younger than Exi’s and Shanyuan’s, may be develop short time.Under the influence of neotectonics movement, the features of the study area manifest Multiple generations and karst gorges and planation surfaces appear alternately; at the same time, the planation surfaces are to be transformed different intensity by the later tectonic movement and its features on the different setting appear characteristic. In the dividing ridge far away from modern water-draining ground, grounding integration is still favorable because the geomorphology is not largely affected under the periodically--enlivened, and the karsts geomorphology here mainly represents cone fengcong-depression. However, most region, which is affected by the periodically—enlivened, that Higher Plateau Phase and Hilly Plateau Phase were uplifted to different altitude, so river drainage systems began to cut down on the hilly plateau phase earth surface to form gorges with steep banks and releases a scenery of core-shaped karst topography and reflects a youth period of karsts development period. Some places, but in minority, are still in the middle period. Therefore, The variety of distribution and combination karst geomorphic features can reflect the evolution history of karstification processes.(4) It involved three evolved stages of Exi stage, Shanyuan stage, Pengdi stage and Gorge stage to form the geomorphic framework including karst leveling plane and dissected gorges in the lower reaches of Wujiang,We have a more clear understanding the features, development and evolution process of of subtropical karst gorges because of the study on karst gorge in the lower reaches of Wujiang, so, this study sheds light on the formation and evolution of the Yangtze River Three Gorges. Meantime, the karst landform, s evolution of the lower reaches of Wujiang is affected by neotectonic movement and hydrodynamic conditions, this make erosion and corrosion to Superimpose, and to make the development intensity increases, all this can form beautiful Wujiang river gorge, but to make the ecological environment become more fragile, this bring up to some disasters such as flood and drought, soil erosion, desertification, land subsidence and so on. We also note that there are the role of different karstication intensity and role in different settings,and this imply us that we must know the karst landform different features of the different surfaces and karst geoge in land use, water resources development,and environmental protection.更多还原