Some scholars have divided the geological-climatic zones that are most suitable for karst in the world, namely, the Appalachian-Caribbean karst zone, the karst zone in western Europe and the northern shore of the Mediterranean, the karst zone in East Asia, South Asia and the equatorial Pacific. China is the most concentrated karst area in the post-karst area. Many countries in the world have important karst areas, as shown in Figure 3-58.
Fig. 3-58 distribution map of major carbonate rocks in the world (according to Fordetal. , 1989)
Europe's France, Germany, Britain, Ireland, Italy, Austria, Russia, Lithuania, Ukraine, Norway, Spain, Serbia, Slovenia, Bosnia and Herzegovina, Croatia, Albania, Greece, Turkey, Switzerland, Sweden, Hungary, Czech Republic, Poland, Romania; United States, Canada, Brazil, Cuba, Mexico and Puerto Rico; China, Japan, Indonesia, Thailand, Myanmar, Singapore, Malaysia, Vietnam, Cambodia, South Korea, North Korea, Philippines, Saudi Arabia, Iraq and Lebanon in Asia; Algeria, Zimbabwe, Zambia, Egypt and Madagascar in Africa; Australia in Oceania, Papua New Guinea, etc.
The distribution of karst in the world is briefly introduced.
1. Europe
The karst zone on the east coast of Adriatic Sea, including Slovenia, Croatia, Bosnia and Herzegovina, Serbia and Macedonia, accounts for about 1/3 of the total area of these countries. It has become a typical karst area not only because of its development mode, but also because of its scientific research level. The word karst originated in this area, such as sinkholes, caves, depressions, valleys, etc., and has become an international professional term. Carbonate rocks in this area are mainly developed in Permian, Triassic, Jurassic, Cretaceous and Paleogene, and the alpine movement has laid the geological structure and topographic characteristics. Famous karst scenic spots such as Bostoina Cave and Skotzyan Cave in Slovenia, Plitvece (Sixteen Lakes) in Croatia, Ombra Springs, etc. There are 7 caves in this area, and the depth exceeds 1000 meters.
From CAMBRIAN to Quaternary, carbonate rocks were widely distributed in Italy, but mainly in Mesozoic and Paleocene, which were exposed in the east-west Alps in the north, the Apennines from north to south, Sicily and Sardinia.
There are smithsonite and barite deposits related to Hercynian magmatism in the closed negative topography of CAMBRIAN limestone caves and caves in Sardinia. Many bauxite mines in Italy are filled in closed negative terrain, which shows that they are the products of land and karst period in the early late Cretaceous. The development of modern landforms began in the early Miocene.
There are 10 caves in Italy, with lighting, trails and guides installed. Some caves are used for exploration, religious activities and cave therapy. Well-known caves, such as Forrassasi Cave, have perfect environmental monitoring system, while the big caves in Trieste are famous for their solid tide monitoring devices. Italy has 1 1 caves with a depth of more than one kilometer.
French karst and its research are in the forefront of the world, and its carbonate rocks account for115 of the national territory, and are distributed in the Mediterranean semi-arid climate zone from humid maritime climate to southeast Europe. Carbonate rocks developed from CAMBRIAN to Neogene. There are six caves with a depth of over 1000 meters and a length of over 50 kilometers.
Carbonate rocks in France are mainly distributed in the western foothills of the Alps and the northern foothills of the Pyrenees, and are strongly folded and fractured. The limestone plateau is around the central plateau of crystalline rocks in south-central France, and extends to the Aldan block in the northeast. In the north is the Paris basin and buried limestone. A series of ancient karsts developed intermittently in late Paleozoic and Mesozoic Cenozoic.
There are nearly 70 caves for public sightseeing in the above-mentioned carbonate outcropping area, such as Ahman Cave, Orangshe Cave, De Mancelle Cave, Cramus Cave and Ognja Tangke Cave. There are also many karst development points, such as Tianshengqiao and Karst Springs, which are also open for sightseeing. More than 100 caves in the Weize River valley are the world cultural heritage of prehistoric cultural sites, including the famous caves in lashko. In order to protect the cave paintings, a lashko cave was copied nearby for sightseeing, and the original cave was sealed.
Many countries in Central and Eastern Europe, including Austria, Hungary, Romania, Czech Republic and Slovakia, have developed Mesozoic carbonate rocks and early Paleozoic carbonate rocks in the Alps and Carpathian Mountains in the east. The karst distribution area in these countries is generally below 5000km2, and only Austria exceeds 10000km2.
80% of the carbonate rocks in Austria are distributed in the Alps formed by the limestone belt in the north, with 14 caves with a depth exceeding 1000 meters and 9 caves with a depth exceeding 50 kilometers.
There are many tourist caves in these countries, especially the Austrian ice caves, the hot water caves in Budapest, Hungary, and the Agger telek caves across the border between Hungary and Slovakia, which have become world natural heritage.
In the CIS countries dominated by Russia, carbonate rocks are widely distributed. From the perspective of structural units, many units such as Russian (Eastern Europe) and Siberian Shield, Ural Orogenic Belt, Alps, Lake Baikal, Far East Fold Belt and so on have developed karst.
The development span of carbonate rocks is from Proterozoic to Mesozoic. The development of karst is influenced by climate zone. In addition to the Mediterranean climate karst in the Black Sea region, it is characterized by temperate zone and cold zone. Affected by glaciation, ice caves have also developed, especially in karst areas such as Urals, Crimea, Caucasus and Tianshan Mountains.
Especially in the orogenic belt of Georgia, there are seven caves with a depth exceeding 1000 meters. Among them, the deep caves in the Caucasus and the Black Sea rank first in the world, with a depth of 2 164m ... Uzbekistan in Central Asia has also developed caves with a depth of more than1000m and a total length of more than 50km. In the cave system developed in Ukraine, there are two caves with a length of more than 50km, of which the total length of gypsum cave is 2 15km, ranking third in the world.
2. America
Except Alaska, 15% of American territory is limestone and gypsum or other soluble rocks exposed or close to the surface. The East Atlantic Ocean and Gulf Plain are composed of Paleogene, Neogene and Cretaceous limestone and chalk from Carolina to Florida along the Pacific Ocean and Gulf of Mexico, which are distributed in strips along the inner edge of the plain. The central and eastern areas where Paleozoic and other ancient rocks are distributed are Appalachian mountains and inland lowlands. From CAMBRIAN to Mississippi (Early Carboniferous), carbonate rocks developed well in karst. Carbonate rocks in the Great Plains are mainly distributed in southern New Mexico. The rocky mountain areas in the west are mainly distributed in the late Paleozoic and Triassic limestone, which are many narrow and discontinuous areas.
Among the cave systems over 50km in length in the world, the United States accounts for 10, and the mammoth cave system reaches 590.629km, ranking first in the world.
There are nearly 200 tourist caves in the United States, with lighting and trail facilities and guided by tour guides, which is second only to China in the number of tourist caves in the world. In addition to caves, other karst landforms and hydrological attractions are also open to the public. Carbonate rocks are very developed in Caribbean islands such as Cuba and Jamaica and countries such as Mexico. Jamaica's famous mountainous area is composed of steep and deep closed depressions or dissolved barrels and conical peaks, which are limestone of Paleogene and Neogene. Mexico has nine caves with a depth of more than 1000 meters and six caves with a length of more than 50 kilometers, which is one of the areas concerned by the international cave community.
Karst in Canada also has a certain distribution. The world-famous Niagara Falls developed on the dolomite stratum. Canada has a cold climate, and the development of many caves is related to the role of ice water. However, Professor D.C.Ford believes that they should still be regarded as general karst, not ice water karst.
Due to the control of climatic conditions, the karst in Cuba and Puerto Rico has the characteristics of tropical karst. Cuba also has a tower-shaped karst landscape, but it is not as typical and distinctive as the peak forest and peak cluster landscape in the south of China. The carbonate rocks in Puerto Rico are new in age and have large porosity.
3. Asian region
A series of caves have developed in Qiu Ji Terrace of Yamaguchi Prefecture in southwestern Japan, such as Yingke Cave (4400 meters long and 145 meters deep) and Fang Qiu Cave (2200 meters long and 128 meters deep). These caves are mainly formed by the dissolution of carbonate rocks by water supplied by atmospheric precipitation infiltration.
Halong Bay in northern Vietnam has a karst landscape of Haifeng forest.
There are many metamorphic limestone in Kuala Lumpur, the capital of Malaysia, and its surrounding areas, which are surrounded by granite, and limestone contacts granite through faults. Kuala Lumpur is a relatively flat quasi-plain, and there are also landscapes similar to peak forests. Limestone is buried underground1000 mm, and the metamorphic process of limestone in Kuala Lumpur has hydrothermal karst, which is due to the dissolution of limestone by hydrothermal solution rich in carbon dioxide from the deep earth and the dissolution of metamorphic limestone by normal precipitation in the later period. There are stone forests with a height of 20 ~ 40m in Sarawak, covering an area of about 0.5km2.
Large carbonate rocks are also deposited in the southwest of Turkey from Antalya to PaMukalay. Located in the northern Mediterranean coastal zone, the annual rainfall can reach more than 1000mm, and the subtropical broad-leaved forest is lush, and the climate is similar to that of southeast China and Guangdong. But the difference is that China is influenced by monsoon, and high temperature and rainy weather occur at the same time in hot season, which makes tropical and subtropical karst landscapes widely developed. On the other hand, Turkey has a Mediterranean climate, with dry season in summer and rainy season in autumn and winter. The high temperature season is separated from the rainy season, and accordingly there is no karst landscape such as peak forest. However, in the inland highlands far away from the coastal zone, the karst sinkholes and underground karst passages that disappear from surface water to underground are still relatively developed due to the reduced rainfall and semi-arid climate. The geological and structural conditions in this area lead to hydrothermal karst from deep place, which makes the dissolved carbonate rock component-calcium carbonate (CaCO3) leak to the surface with the karst hot mineral water. After the karst hot mineral water gushed out of the surface, due to the change of temperature and water pressure and biological action, a large area of travertine deposits were produced in the valley with a height difference of 90 meters in Pamkari area, forming travertine waterfalls, travertine dams and travertine terraces, which constituted a unique karst landscape. In the local language, "Pamkari" means cotton fort, that is, from a distance, it is like white and soft cotton on multi-level terraces. These "cotton" are actually travertine deposits.
Two thirds of Lebanon is a karst area, and there are slopes, depressions, valleys, funnels, blind valleys and sinkholes on the surface. There are underground rivers, lakes and underground rivers. The active crustal uplift from the middle Mesozoic to Pliocene led to the opening of the Red Sea Rift, the separation of the Arabian plate from the African plate, and related depressions and faults, which all played a major role in controlling the karst development in Lebanon and its adjacent areas. The surface of this area is relatively dry, and sharp gullies and valleys can also be seen from the karst landform, which has the characteristics of tropical karst. Underground karst water is active and many karst springs appear. The maximum spring flow can reach 65438+1100m3/s, and the multi-spring flow can reach 0.28 ~ 2.83m3/s. ..
4. Oceania
There are carbonate rocks under the Nalabo Plain in southern Australia, which is located in semi-arid and arid karst areas with an area of 200,000 km2. The surface karst phenomenon is developed and the vegetation is not good. There are only 3 ~ 5m undulating gullies and shallow depressions (length 10 ~ 15m, depth 2 ~ 3m), but there are also karst collapses and sinkholes, and underground James is also well developed. The decline of sea level during the ice age and igneous rocks deep in the earth's crust all affected karst.
5. Africa, South America
Both Africa and South America belong to the ancient Gondwana continent, and after the land was formed, it never sank to the bottom of the sea. Therefore, the areas where carbonate rocks developed and exposed on these two continents are very small, and only a few areas have karst landforms. Madagascar island in the east of the African continent is famous for its sword-shaped karst (stone forest).
At present, more than 50 of UNESCO's more than 800 world cultural and natural heritages are related to karst, which has both cultural and natural heritages and is characterized by biodiversity and geoscience diversity. These sites include caves, karst springs, surface karst landscapes and calcareous sediments, historical and cultural relics, fossil producing areas and religious temples. Needle karst in Madagascar and Malaysia belongs to the same type as Yunnan Stone Forest. Many of these heritages are famous tourist attractions.