Spatial and temporal distribution patterns of karst tourism geological resources in China

In general, from the south to the north, the karst landscape changes from peak clusters and peak forest landscapes to karst hills, and then gradually turns into karst mountains.

The distribution rules of my country's surface karst geological landscape are as follows:

(1) Karst landscape types are complete and of high grade. my country's karst surface morphology is well developed, especially the tropical karst peak forests and semi-arid temperate karst spring caves and layered canyons are world-famous. The relative height is generally 100-300m, and the average height on the Guilin Fenglin Plain is 74m. The slope of the peak forest is 45°, and some are even greater than 60°. The total area is about more than 100,000 km2, accounting for nearly 10% of the total karst area in the country.

There are complete types of karst caves spread across the north and south. There are more than 8,000 tourist caves in the world, with more than 26 million tourists annually. It is estimated that China has currently developed 217 tourist caves, of which karst caves account for about 3/4. There are more than 1,800 known caves in Yunnan Province, more than 2,000 in eastern and southern Guizhou, and 1,030 in Anshun and Pingba counties alone, with an average density of 0.7/km2 (Guizhou Normal University Cave Resource Survey Team, 1989), Guangxi There are more than 300 within 150km2 of Guilin.

(2) The distribution of karst tourism resources has obvious regional and stratigraphic selectivity. Based on the ancient geographical location recovered from paleomagnetic data and the preserved paleokarst morphology, Weng Jintao divided the development period of China's paleokarst into five main periods, namely the Proterozoic Era, the Early Paleozoic Era, the Late Paleozoic Era, the Mesozoic Era and the Tertiary Era. Ancient karsts in different periods in China were mainly formed in tropical and subtropical humid climate environments. The Miocene is the dividing period between ancient karsts and modern karsts in China. Northern China gradually changed to a dry and cold environment after the Middle Pleistocene, which was conducive to the preservation of the ancient karst landscape formed in the humid climate of the Tertiary Period; while southern China has been in a hot and humid climate environment since the Quaternary Period, and many karst forms continued to develop. .

It is precisely because the development of karst in my country has obvious stages and the paleoclimate has obvious regional differences that the distribution of karst landscapes in my country has strong regional differences and dependence on stratigraphic layers.

Most of the karst scenic resources that have been developed in my country are in the south of the Yangtze River, accounting for 83% of the total number of karst scenic spots in the country. Among them, the South China District ranks first in the country; the number of karst scenic spots in this region accounts for 83% of the total. It accounts for 38% of the number of scenic spots and 35% of the total number of karst scenic spots in the country. The karst landscapes in national geoparks and world geoparks are also mainly distributed in southwest and south China. A small amount is found in Liaoning, Beijing and Shandong.

In Guangdong, Guangxi, Guizhou, and the eastern Yunnan Plateau, the climate is hot, the rainfall is abundant, the rainfall is greater than the evaporation, and the carbonate rock pure layer is thick, and erosion-dissolution or dissolution is the main process. It is a tropical karst. In the development area, the geological landscape of peak clusters and peak forests and underground rivers with large flows have developed, and their distribution range is similar to the 1400mm isohyet line. The crust of the Guizhou and East Yunnan Karst Plateau has been intermittently uplifted sharply in the late recent period, resulting in deep incision of river sources. Peak clusters, peak forests, depressions, troughs, etc. are distributed in layers, showing the characteristics of a composite geological landscape. For example, in the Maolan Karst Forest Nature Reserve, there are sinkholes, funnels, depressions, troughs, blind valleys, slope protection, and peak cluster-funnel, peak cluster-depression and peak cluster-basin combinations; the peak forest in Yunnan Stone Forest- Cave-karst lake.

In the eastern Sichuan and western Hunan and Hubei regions, the temperature and rainfall are not as good as the former, the chemical effects are weakened and the physical effects are strengthened. Mainly based on erosion-dissolution, the geological landscape of karst hills and karst depressions, as well as karst vermilion and underground rivers with large flows, are developed.

The northern region still accounts for 16% of similar resources in the country. Although North China accounts for only 12% of the same kind in the country, it accounts for 28% of the total number of local scenic spots, and is unique for its karst springs. The Northeast region also accounts for 20% and 4% of the total local resources and the total number of similar resources in the country respectively, and is characterized by coastal submarine springs and one of the few volcanic lava storage caves in the world.

In the northern region, due to the dry climate and low rainfall, surface karstification is weak and erosion is further enhanced, with dissolution-erosion being the main factor. The karst geological landscape formed is significantly different from that in the south. The karst surface has a single form, with mostly dry valleys and springs, followed by karst caves, sinkholes, karst ditches, etc. The surface karst is not very developed, forming a surface landscape dominated by karst mountains and karst springs. In contrast, in the arid and semi-arid karst areas in northern my country, the degree of karst development is weak. The surface is dominated by normal mountains and normal hills. The more common form of dry valleys, small surface forms and underground forms are less developed than in hot and humid climates. Much worse, see Table 22.

Table 22 Comparison of karst development in arid and semi-arid areas and tropical and subtropical areas

In some areas, the annual precipitation can reach 500mm and the climate is hot and humid. For example, the karst area in the eastern Taihang Mountains of Shanxi has dense karst areas. There are karst ditches, karst troughs, and caves 600 to 1000m long underground. The karst in the Fangfangshan Nature Reserve in Beijing is of this type. The Yunshui Cave developed in the late Proterozoic dolomitic limestone is one of the longest karst caves in northern my country, with a length of 612m.

In the nature reserves of karst geological landscapes, there is also a special type of karst landscape, namely the Huanglong and Jiuzhaigou travertine accumulation landscapes in Sichuan Province. Travertine, also known as travertine, belongs to the groundwater origin series.

The sculptural landscapes formed in the area include travertine, edge stone dams and colorful pools, travertine barrier lakes, travertine waterfalls, travertine beach flows, travertine beach dams, travertine platforms, travertine caves, and travertine "bonsai" As well as potholes developed in travertine bodies, this kind of landscape stretches for more than ten kilometers. What's even more amazing is that a complete plant support was found in the travertine lake embankment in Jiuzhaigou, which makes the travertine landscape look rough and gives people a "wild" feeling. Huanglong's travertine edge stone dam colorful pool is wrapped with plant organs or algae organisms. The scenery is beautiful and gives people a "showy" feeling.

In addition, alpine karst geological landscapes can also be seen in the Altyn Mountains of Xinjiang, Shangri-La of Yunnan, Tibet and northwest Sichuan. To sum up, my country's karst caves are mainly distributed in Southwest and East China. There are 35 stone forests in my country. The Yunnan Stone Forest is the most famous. Its scale and shape are far superior to similar types of landscapes across the country: peak clusters and peak forest landforms. Guilin in Guangxi, Xingyi in Guizhou, and Luoping in Yunnan are relatively concentrated; karst canyons and waterfalls generally appear, such as Huangguoshu in Anshun, Guizhou, Maling River in Xingyi, Tiger Leaping Gorge and Shangri-La Grand Canyon in Diqing, Yunnan, etc. ; Karst springs are represented by Jiuzhaigou, Huanglong, Sichuan, and Baishui Tai, Zhongdian, Yunnan. Table 23 shows the China National Geoparks with karst as the main landscape.

Table 23 China National Geoparks with karst as the main landscape