The Qaidam, Tsaidam, or Chaidamu Basin is a hyperarid basin that occupies a large part of

Haixi Prefecture Haixi Mongolian and Tibetan Autonomous Prefecture (; mn, ᠬᠠᠶᠢᠰᠢ ᠶᠢᠨ ᠮᠣᠩᠭᠣᠯ ᠲᠥᠪᠡᠳ ᠦᠨᠳᠦᠰᠦᠲᠡᠨ ᠦ ᠥᠪᠡᠷᠲᠡᠭᠡᠨ ᠵᠠᠰᠠᠬᠤ ᠵᠧᠦ; bo, མཚོ་ནུབ་� ...

Qinghai Province Qinghai (; alternately romanized as Tsinghai, Ch'inghai), also known as Kokonor, is a landlocked province in the northwest of the People's Republic of China. It is the fourth largest province of China by area and has the third smallest pop ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

. The basin covers an area of approximately , one-fourth of which is covered by saline lakes and playas. Around one third of the basin, about , is desert.

Name

''Tshwa'i 'Dam'' is the Wylie

romanization Romanization or romanisation, in linguistics, is the conversion of text from a different writing system to the Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing written text, a ...

of the

Tibetan Tibetan may mean: * of, from, or related to Tibet * Tibetan people, an ethnic group * Tibetan language: ** Classical Tibetan, the classical language used also as a contemporary written standard ** Standard Tibetan, the most widely used spoken diale ...

name , meaning "

Salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

Marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...

"; the Tibetan Pinyin romanization of the same name is ''Caidam''. ''Qaidam'' is the GNC

of its transcription into Mongolian; ''Tsaidam'' is a variant romanization of the same name. ''Chaidamu'' is the

pinyin Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese fo ...

of its transcription into

Chinese characters Chinese characters () are logograms developed for the writing of Chinese. In addition, they have been adapted to write other East Asian languages, and remain a key component of the Japanese writing system where they are known as ''kanji ...

; the same name was formerly romanized as the for the Chinese Postal Map.

Geography

Orographically Orography is the study of the topographic relief of mountains, and can more broadly include hills, and any part of a region's elevated terrain. Orography (also known as ''oreography'', ''orology'' or ''oreology'') falls within the broader discipl ...

, the Qaidam Basin is a comparatively low area in the northeastern part of the Qinghai–Tibet Plateau.. With an elevation of around , Qaidam forms a kind of shelf between Tibet to the south (around ) and

Gansu Gansu (, ; alternately romanized as Kansu) is a province in Northwest China. Its capital and largest city is Lanzhou, in the southeast part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibe ...

to the north (around ). A low water divide separates the Qaidam Basin proper from that of Qinghai Lake to the east. Despite this lower elevation, Qaidam is still high enough that its mean annual temperature is despite lying on the same latitude as

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wi ...

, and

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. The crescent-shaped basin covers an area of approximately . Its substrate is broadly divided into three blocks: the Mangya Depression, a northern fault zone, and the Sanhu Depression. Qaidam is an intermontane basin, surrounded on all sides by mountain ranges. In the south, the

Kunlun Mountains The Kunlun Mountains ( zh, s=昆仑山, t=崑崙山, p=Kūnlún Shān, ; ug, كۇئېنلۇن تاغ تىزمىسى / قۇرۇم تاغ تىزمىسى ) constitute one of the longest mountain chains in Asia, extending for more than . In the bro ...

separate it from the higher central section of the

Tibetan Plateau The Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the Ti ...

. In the north, a number of smaller ridges like the Shulenanshan separate it from another higher plateau, which usually referenced by the name of its northern escarpment, the Qilian or Nanshan. In the northwest, the Altyn-Tagh separates it from the

Kumtagh Desert The Kumtag Desert (, "kum-tag" meaning "sand-mountain" in a number of Turkic languages), is an arid landform in Northwestern China, which was proclaimed as a national park in the year 2002. Definitions Broad The oval Tarim Basin with its central ...

of southeastern

Xinjiang Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwes ...

Because of this position, Qaidam forms an endorheic basin accumulating lakes with no outlet to the sea. The area is among the most arid non-polar locations on earth, with some places reporting an aridity index of 0.008–0.04. Across the entire basin, the mean annual rainfall is but the mean annual evaporation is . Because of the low rainfall, these lakes have become saline or dried up completely. Presently, there are four main playas in the basin: Qarhan in the southeast and (from north to south) Kunteyi, Chahanshilatu, and Dalangtan in the northwest. These playas and a few other saline lakes occupy over one-fourth of the basin, with the sediments deposited since the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

as deep as 10 to 14 km (6–9mi) in places despite tectonic activity having repeatedly shifted the center of the region's sedimentation. The seasonal nature and commercial exploitation of some of the lakes makes an exact count problematic: one count reckoned there were 27 lakes in the basin,. another reckoned 43 with a total area of . The aridity, salinity, wide diurnal and seasonal temperature swings, and relatively high ultraviolet radiation has led to Qaidam being studied by the China Geological Survey as a

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

analogue for use in testing

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...

and equipment for China's 2020 Mars rover program.

Geological history

Qaidam was part of the North China Craton from at least 1 billion years ago, before breaking off million years ago at the end of the Neoproterozoic. It was an island in a shallow sea until uplift beginning around 400 Ma finally rejoined it to the mainland by 200Ma. Three-dimensional modeling shows that the present basin has been squeezed to an irregular diamond shape since the beginning of the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

, with the

Indian Plate The Indian Plate (or India Plate) is a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian Plate broke away from the other fragments of Gondwana , began ...

beginning to impact the ancient

shoreline somewhere between 55–35Ma. At first, Qaidam was at a far lower elevation. Pollen found in core samples shows that the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

(34–23Ma) was relatively humid. A great lake slowly formed in the western basin, which two major tectonic movements raised and cut off from its original sources of sediment. At its greatest extent during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

(23–5Ma), this lake spread at the present elevation contour over . and was among the largest lakes in the world. Nutrient-rich inflows contributed to

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

blooms, which supported an ecosystem that built up reserves of organic carbon. The Tibetan plateau's uplift, however, eventually cut it off from the warm and humid Indian monsoon. It went from a forest steppe to a

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

. By 12Ma, the climate had dried enough to break Qaidam's single lake into separate basins, which frequently became saline. During the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Kunteyi but, during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

(after 2.5Ma), tectonic activity shifted the basin's tributaries and floor, moving the focus of sedimentation from the Dalangtan to Qarhan area. During this time, the record's glacial intervals suggest a low-temperature climate and its

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

yardang A yardang is a streamlined protuberance carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion by dust and sand and deflation (the removal of loose material by wind turbulence.) Yardangs become e ...

s attest to strong winds. From 770,000 and 30,000 years ago, the enormous lake which filled much of the southeastern basin alternated nine times between being a fresh- and saltwater lake. Pollen studies suggest the bed of Dabusun Lake in the Qarhan Playanearly the lowest point of the basinwas elevated about within the last 500,000 years. At around 30 kya, this greatat the time, freshwaterlake spread over at least with a surface above the present levels of its successors. At the same time, a river from the "Kunlun" paleolake to its south was enriching the Sanhu region with enormous reserves of

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense soli ...

derived from

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...

s near Mount Buka Daban which now feed into the Narin Gol River that flows into East Taijinar Lake. Around 30 kya, the lake in the Kunluns dried up and the Qarhan was cut off from sufficient inflows of fresh water. It became saline again, beginning to precipitate salts about 25,000 years ago.. The basin's continuing formation and evolution is controlled by the Altyn Tagh fault constituting the northern basin boundary.

Resources

The basin's large mineral deposits caused a great deal of investment interest from 2005.

Qarhan Playa The Qarhan Playa or also misleadingly described as , is a playa in the Golmud and Dulan counties of Haixi Prefecture, Qinghai, China. Formerly a single unitary lake, it is now an expansive salt flat divided into four greater sections ( Dabu ...

, a salt flat including about ten of the lakes, contains over 50 billion metric tons (55 billion short tons) of

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

. Beneath the salt, Qaidam is one of China's nine most important petroliferous basins and its largest center of onshore production. The Qinghai Oilfield, exploited since 1954, includes the Lenghu, Gasikule, Yuejin-2, and Huatugou oil fields and the Sebei-1, Sebei-2, and Tainan gas fields. All together, it has proven reserves of 347.65 million metric tons (more than 2 billion

barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

) of

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

and 306.6 billion cubic meters (10.83 trillion cubic feet) of

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...

. Annual production capacity is about 2 million metric tons of petroleum and 8.5 billion cubic meters of natural gas. A pipeline connects the Huatugou field with the major refinery at

Golmud Golmud, also known by various other romanizations, is a county-level city in the Haixi Mongol and Tibetan Autonomous Prefecture of Qinghai Province, China. It is now the second-largest city in Qinghai and the third largest in the Tibetan ...

, and the Sebei gas fields are connected to

Xining Xining (; ), alternatively known as Sining, is the capital of Qinghai province in western China and the largest city on the Tibetan Plateau. The city was a commercial hub along the Northern Silk Road's Hexi Corridor for over 2000 years, and w ...

, Lanzhou, and

Yinchuan Yinchuan (, ; ) is the capital of the Ningxia Hui Autonomous Region, China, and was the capital of the Tangut-led Western Xia dynasty. It has an area of and a total population of 2,859,074 according to the 2020 Chinese census, and its built ...

. Qaidam has reserves of

asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

borax Borax is a salt (ionic compound), a hydrated borate of sodium, with chemical formula often written . It is a colorless crystalline solid, that dissolves in water to make a basic solution. It is commonly available in powder or granular form ...

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywa ...

, and several

metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...

s, with the greatest reserves of

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...

, and

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

of anywhere in China.

Transportation

The Xining-Golmud rail line (the first stage of the Qinghai–Tibet Railway), which crossed the eastern part of the Qaidam Basin in the early 1980s, is an essential transportation link for accessing the region's mineral resources. As of 2012, additional rail lines are under construction. The construction of the Golmud–Dunhuang Railway started in October 2012; it is expected to be completed within 5 years.格尔木至敦煌铁路开工
, ''Renmin Tielu Bao'', 2012-10-20 In the early 2012, Zangge Potash Co Ltd started the construction of a 25-km private railway from the Qarhan station on the Qinghai–Tibet Railway (near the eponymous salt lake) to their facilities nearby. As of the late 2013, preliminary planning is conducted for the Golmud-Korla Railway, which will stretch along the entire western part of the Qaidam Basin as well.库尔勒—格尔木铁路项目预可研报告获批
(Korla-Golmud Railway project preliminary feasibility study report approved), 中华铁道网, 2013-09-30

References

Citations

Bibliography

* . * . * . * . * . * . * . * . * . * . * . * . * . * . * . * .

External links

"Qaidam"
in the ''

Columbia Encyclopedia The ''Columbia Encyclopedia'' is a one-volume encyclopedia produced by Columbia University Press and, in the last edition, sold by the Gale Group. First published in 1935, and continuing its relationship with Columbia University Columbi ...

''
Qaidam Basin Photos
from

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

{{coord, 37, 16, N, 94, 27, E, region:CN_type:landmark, display=title Landforms of Qinghai Drainage basins of China