Qaidam Basin

Qaidam Basin

This entry is compiled and applied by "popular science China" Science Encyclopedia

to examine

.

Qaidam Basin is one of the three inland basins in China. It is a huge closed Intermountain fault basin and one of the four major basins in China.

It is located in the northwest of Qinghai Province, northeast of Qinghai Tibet Plateau, mainly in Haixi Mongolian and Tibetan Autonomous Prefecture. In the northwest, it reaches the Altun Mountains in the north, the Kunlun Mountains in the southwest, and the Qilian Mountains in the northeast, covering an area of 240000 square kilometers

. Inland is rich in iron ore, copper, tin, salt and other minerals, so it is called "cornucopia". The Qaidam desert in the hinterland ranks the fifth among the eight deserts in China.

Geographical features

Qaidam Basin is a plateau basin, located in the northwest of Qinghai Province, mainly in Haixi Mongolian and Tibetan Autonomous Prefecture. It is a closed basin surrounded by Kunlun Mountain, Altun mountain, Qilian Mountain and other mountains, between 90 ° 16 ′ e-99 ° 16 ′ E and 35 ° 00 ′ n-39 ° 20 ′ n. The basin is slightly triangular, 800 km long from east to west and 300 km wide from north to south, covering an area of 240000 square kilometers

It is one of the three inland basins in China.

Qaidam Basin is one of the four largest basins in China, with the highest topography. Qaidam is more than a world of salt

Besides, it is also rich in oil, coal and various metal deposits, such as the oil in Lenghu, the coal in Yuka and the lead-zinc mine in Xitieshan. Therefore, Qaidam Basin has the reputation of "cornucopia".

geological structure

The basement of the basin is Precambrian crystalline metamorphic rock series. The terrain inclines slightly from northwest to Southeast, and the altitude gradually drops from 3000 meters to about 2600 meters. From the edge to the center, alluvial gravel fan (Gobi), alluvial proluvial silty plain, lacustrine alluvial silty clay plain and lacustrine silt saline plain change in turn. Salt lakes and swamps are widely distributed in low-lying areas.

The inner margin of the Gobi belt in the northwest of the basin is relatively high, and the hills below 100 meters are clustered. In the southeast of the basin, the subsidence is intense, and the alluvial and lacustrine plain is wide. The main lakes such as the South and North huoluzon lake and dabushun lake are distributed here. There are large marshes along the lower reaches of Chaidamu River, sulinguole River and Golmud River and around the lakes.

In the northeast of the basin, there are a series of low mountain fault block uplifts of metamorphic rock series, which form a small Intermountain basin between the basin and Qilian Mountains. From west to East, there are huahaizi, Dachaidan, XIAOCHAIDAN, Delingha and Wulan basins. The rivers in these basins flow into the lakes in their low-lying centers.

Most of the rivers are intermittent, and there are only more than 10 regular rivers in the total of 100 rivers, which are mainly distributed in the east of the basin, and the water network in the west is very sparse. There are more than 20 salt lakes in the basin.

climate

main features

Qaidam Basin belongs to plateau continental climate, with drought as the main feature. The annual precipitation decreases from 200 mm in the southeast to 15 mm in the northwest. The average annual relative humidity is 30-40%, and the minimum is less than 5%.

The annual average temperature of the basin is below 5 ℃, and the temperature changes violently. The absolute annual temperature difference can reach above 60 ℃, the daily temperature difference is often around 30 ℃, and it can drop to below 0 ℃ at night in summer. The wind is strong, and the number of strong wind days above grade 8 per year can reach 25-75 days. The strong wind of 40 m / s can even appear in the west, and the wind erosion is strong.

climate change

From 1961 to 2006, the temperature increase in China was 0.10 ℃ - 0.20 ℃ every 10 years, while that in Qinghai Plateau was 0.33 ℃ every 10 years. Among them, the temperature of Qaidam Basin is as high as 0.44 ℃ every 10 years. Therefore, Qaidam Basin has become the most significant warming area in Qinghai Plateau and even in the whole country.

With the increase of temperature, the precipitation in Qaidam Basin is also increasing. The precipitation in most areas of Qaidam Basin has been increasing since 1998, and the increasing trend is obviously larger than that in other areas of Qinghai Province. From 1998 to 2008, the annual average precipitation in the Qaidam Basin ranged from 13.5 mm to 95.5 mm. Compared with the average over the years, the precipitation in most areas increased by more than 10%.

The Qaidam Basin is also the most sensitive and significant area of climate change in the Qinghai Tibet Plateau. All kinds of signs show that the climate in Qaidam Basin is changing from warm and dry to warm and humid.

Disastrous weather

On March 17, 2011, affected by the cold air moving eastward in Xinjiang, from 1:33 am to 2:28 am, a disastrous dust weather occurred in Golmud, Qaidam Basin, Qinghai Province, with the maximum wind speed of 26.3 meters per second. This is also the sandstorm weather with the highest wind speed in the past 40 years in Qaidam Basin, which has affected the production and life of local people.

At that time, the maximum visibility was less than 1 meter when dust passed. After the windy and dusty weather, snowflakes floated over Golmud. According to the meteorological department, due to dust and snow weather, the temperature drop in Golmud City reached about 8 ℃.

Latest findings

A team of Chinese and British geologists recently discovered that about 30 million years ago, the climate in the Qaidam Basin was cool, moderate humidity and covered by temperate deciduous broad-leaved forest, which is very different from today's extremely arid climate.

This time, the research team found a 30 million year old fossil flora in the northern Qaidam Basin. The researchers used the analytical program to study these fossils and reconstructed the paleoclimate and PALEOELEVATION at that time by combining with the atmospheric ocean integrated circulation model.

The reconstruction results show that the climate of Qaidam Basin 30 million years ago is cool and moderate, which is different from the cold and arid climate with an average annual temperature of 1.9 ℃ and an annual precipitation of 82.7 mm. At that time, the annual average temperature there was about 11.6 degrees Celsius, the temperature was close to freezing point in winter and cool in summer, and the seasonal difference of temperature was far less than now. At that time, the annual precipitation is likely to be more than 1000 mm, dry in summer and wet in winter, and the seasonal difference of precipitation is relatively low. However, the Qaidam Basin 30 million years ago is similar to today's: at that time, the altitude there reached about 3.3 km, which is similar to the current elevation of the basin.

The Qaidam Basin 30 million years ago was covered with temperate deciduous broad-leaved forest dominated by poplar and leguminous plants. Under the control of the westerly belt, the ocean that once crossed Eurasia brought abundant water vapor to nourish the growth of plants.

The related research results have been published in the international well-known geoscience journal earth and Planetary Science Communication in early March 2010.

ecological environment

Vegetation condition

The natural landscape of Qaidam Basin is arid desert, and the main soil types are saline desert soil and gypsum desert soil. The latter is mainly distributed in the west of the basin, and the meadow soil and swamp soil are generally salinized. There are less than 200 species, mainly shrubs, semi shrubs and herbs with high drought resistance, and more halophytes. The vegetation structure is simple, about 6 / 10 of the flora is composed of one or several species.

In the piedmont alluvial fan and alluvial proluvial plain, desert vegetation communities composed of Ephedra burnetii, Haloxylon ammodendron and red sand shrubs are dominant; in salt marshes, salt lakes and river banks, sedges are densely growing to form grass mounds, in which the dominant halophytes are iris purpurea, Scirpus triqueter and Carex nigra; in the periphery of salt lakes and marshes, reeds and Leymus are dominant

.

Animal distribution

The fauna of Qaidam Basin is characterized by the transition from Mongolia Xinjiang region to Qinghai Tibet region. Wild animals mainly include wild camel, wild donkey, wild yak, yellow sheep, green sheep, marmot, wolf, horse bear, deer, fox, badger, etc. As a result of cultivation and hunting, wild animals are greatly reduced, and some are on the verge of extinction.

resource development

mineral resources

Qaidam Basin is located in the west of Qinghai Lake. Although it is desolate, it is rich in products. It is rich in salts and other chemical elements. It mainly includes salt, boron, potassium, magnesium, lithium, rubidium, bromine, iodine, strontium, cesium, gypsum, Glauber's salt, natural alkali, etc., with more than 60 billion tons of salt. The basin is rich in lead, zinc, chromium, manganese and other metals, as well as coal, petroleum, asbestos and other resources. The most famous are all kinds of salt. Among them, the proved reserves of sodium salt are more than 53 billion tons; the proved reserves of potassium chloride are more than 200 million tons, accounting for 97% of the total reserves in China; the proved reserves of boron are more than 11 million tons, accounting for half of the total reserves in China; and the proved reserves of magnesium chloride are about 2 billion tons. Qaidam Basin is not only the largest salt mine in China, but also the largest salt mine in the world.

There are more than 200 proven ore spots, including more than 50 kinds, of which the reserves of salt, petroleum, lead-zinc and borax are especially abundant, and the total reserves of table salt are about 60 billion tons. Mirabilite, potash and borate have industrial exploitation value. For example, Chaerhan potash plant has become an important chemical raw material base in China. Oil storage structures are widely distributed in the basin, and there are important oil and gas accumulation zones in the West. Xitieshan Pb Zn deposit is one of the largest known Pb Zn deposits in China.

The Qaidam basin covers an area of 250000 square kilometers, and the potential value of various resource reserves reaches 1

Chinese PinYin : Chai Da Mu Pen Di