The Gobi, a continental desert.
The Gobi desert is a large desert covering the southern part of Mongolia as well as the North and Northwest China. It is located at an altitude of 900 to 1500 m above the sea and measure more than 16000 km from southwest to Northeast and 800 km from North to South. It is bounded on the North by the chain of the Altai Mountains and the steppes of Mongolia; on the West by the Taklamakan desert. to the Southwest by the Siberian plateau; Southeast by the North China plain. It is considered to be the 5th largest desert in the world and the first in Asia.
The Gobi also contains of many mineral resources of gold and copper.
The Gobi desert is considered to be a continental desert. That means that there is a variation in temperature between summer and winter high. Indeed, the winters are cold, see very cold (-40 ° C), while summers are often very hot (+ 50 ° C). The reason for this climate change is that it is immune from a mountain barrier (the Himalayas), which blocks the depressions from the Indian ocean. So the masses of humid air pouring their rain on the side in direct contact with the wind. The other side being sheltered from the wind, water bodies there have a low access, preventing the arrival of rains. We call this phenomenon, shadow rainfall (rain shadow). The rainfall of the Gobi is 154 mm of rain per year.
The Gobi desert is composed of sediment from erosion of the volcanic rocks (granite, basalt, rhyolite) as well as from ocean sediments. Can be easily seen in the desert of clay in the flaming cliff and of many strata of limestone distorted when the orogen of Central Asia (Central Asian Orogenic Belt CAOB), as in the frozen gorges. The flaming cliff are mainly known through the many discoveries of fossils and dinosaur egg.
Orogen of Central Asia (Central Asian Orogenic Belt CAOB)
The orogen of Central Asia and the formation of the mountains such as the Urals, Altai took place during more than 800 Ma, of the Mesoproterozoic (-1600Ma to-1000Ma) Triassic (-252 my to-201Ma). This formation is due to the reconciliation of the supercontinent Gondwana with the Siberia craton and the Tarim-North China craton. This represents a huge area (more than 11% of Asia) of orogenes, collisions, rotations and training of micro-continents from the Urals to the Pacific ocean.
In addition, it is also possible to observe the ocean levels to the sons of the years on the cliffs. Indeed, before the Mongolia, there were many oceans including the Tethys ocean. This ocean is being closed during the CAOB, many relics are visible in the Gobi desert.
During different geological periods, deposits of marine sediments are deposited at the bottom of the oceans. Thus, it is possible to observe on an outcrop of the different strata of sedimentations. This has a strong interest to understand the geology and climate of the time. If you have a large thickness of sediment during a period, this means that there was a strong active erosion.
The Gobi is not a desert in the conventional idea. It is not made only of sand but of different landscapes. There are vast plains of steppe, of Earth, stone or sand, large chains of mountains or small dunes. This heterogeneity of landscapes gives a large variety of colors in the Gobi desert. In addition, the desert contains many wild animals, gazelles, leopards in the snow, eagles, vultures, etc… There are also many horses, camels, wild and domestic.
Desertification by the expansion of the Gobi desert is alarming. Human activity (deforestation, irrigation, overgrazing, etc…) is the cause of the acceleration of the expansion of the desert. In southern China, the expansion of the desert is 3600 km² per year. The increase in storms of the desert 20 years led many economic damage in China. Desertification this Chinese State decided to set up a green wall (Green wall of China) by planting many trees, hoping that the forest can repel desertification.
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For the time scale is here!
“The Altaids of Central Asia: A tectonic evolutionary and innovative review.” WHILEM C., WINDLEY B., SCOTT G., 2012
“Evolution of the Early Permian volcanic-plutonic complex in the western part of the Permian Gobi – Altay Rift (Khar Argalant MTS., SW Mongolia)”. David burianek1 *, Pavel HANŽL, Petr BUDIL, Axel GERDES, 2012