中国喀斯特地貌的演化模式

MODELS OF KARST GEOMORPHOLOGICAL EVOLUTIONS IN CHINA

中国喀斯特地貌的发育与岩性密切相关,并受许多因素的影响与控制。特别是新生代的两个构造事件和更新世的五次气候变换,都影响了喀斯特的发育。在计算典型喀斯特地区的上升、沉降、溶蚀与沉积等速率的基础上,本文重点探讨了喀斯特地貌演化的八个模式。

There are four kinds of bare and semi-bare carbonate beds in China, which occupy about one-fourth of the total area of China.As to the buried carbonate layers, their distributing areas are vaster . According to statistics, areas of the four kinds of bare and buried beds are over 7o percent in the whole territory of China. The accumulated thickness of carbonate beds in many regions reaches 2-3×103 metres, and the largest thickness is about 1.9×103 metres .The development of karst geomorphological landscapes is closely related to the lithological characters and controlled by many natural conditions, particularly the two structural events in Cenozoic era, which are. one, the strongest Up lifting of the Himalayas and upwarping of the Qinghai-Xizang plateau, which were led by the collision between the Indian plate and the Eurasian Continent, the other one is the formations of a series of island arcs in the eastern part of Asia and opening of the marginal sea basins, made by the subducting of the Pacific plate.Besides, the five times of climatic changes in pleistocene always jointed together with the above-mentioned two structural events to influence and to control the karst development .Many rates related to the lifting, descending, dissolution and deposition in typical karst regions have been calculated to discuss the karst geomorphological evolutions.The polyphyletic evolutions in karst regions may be summarized into many models,but this paper introduced only some important ones.1.The strong lifting evolution model, by the collision between the Indian plate and Eurasian Continent, which lifted the Himalayas strongly with unequal upwar ped rates from lower than imm/a to about 50mm/a and is accompanied with the upwarp-ing of Qinghai-Xizang plateau,It may be a typical example.2. Continuous up-warping evolution model. The Yunnan-Guizhou plateau formed by continuous upwarping is an important region to study this evolution model .3. Differential upwaring evolution model, for example in Three Gorges region of Changjing River, where, resulted by from the upwarped Huangling Dome there, the lifting rates are different in its west and east limbs.4. Slowly upwarping evolution model, for example in Guangxi and Guangdong,there are overlappad the strong development of the corrosion phenomena and landscapes in different stages of Quaternary. 5. wide descending evolution model; the bare karst landscapes formed in the early stage had descended widely to turn into duried condition. Fig. 6 can be used to express narrow settling evolution model in east Yunnan. The other two are denuded-exposed evolution model and marine environmental evolution model