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 po ...

, China. The basin covers an area of approximately , one-fourth of which is covered by

saline lake A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...

s 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, an ...

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 quanti ...

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 a ...

"; 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 '' kan ...

; the same name was formerly romanized as the for the

Chinese Postal Map The history of the postage stamps and postal history of China is complicated by the gradual decay of Imperial China and the years of civil war and Japanese occupation in the 1930s and 1940s. In modern times, postal delivery is handled by C ...

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 discip ...

, 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 to the north (around ). A low water divide separates the Qaidam Basin proper from that of

Qinghai Lake Qinghai Lake or Ch'inghai Lake, also known by #Names, other names, is the list of lakes by area, largest lakes of China, lake in China. Located in an endorheic basin in Qinghai Province, to which it gave its name, Qinghai Lake is classified as ...

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 , religi ...

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 wit ...

, and

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

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 primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. 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 br ...

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 T ...

. 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 Altyn-Tagh (also Altun Mountains, Altun Shan; , Pinyin: ''A'erjin Shan'', Wade–Giles: ''A-erh-chin Shan;'' Uyghur'':ئالتۇن تاغ'') is a mountain range in Northwestern China that separates the Eastern Tarim Basin from the Tibetan Plate ...

separates it from the Kumtagh Desert 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 northwest ...

Because of this position, Qaidam forms an

endorheic basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into la ...

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 An aridity index (AI) is a numerical indicator of the degree of dryness of the climate at a given location. A number of aridity indices have been proposed (see below); these indicators serve to identify, locate or delimit regions that suffer from ...

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

s occupy over one-fourth of the basin, with the sediments deposited since the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), 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 J ...

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 The China Geological Survey (CGS) () is a government-owned, not-for-profit, Chinese organization researching China's mineral resources. It is a public institution managed by the State Council’s ministries and commissions responsible for geologi ...

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 atmos ...

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 The North China Craton is a continental crustal block with one of Earth's most complete and complex records of igneous, sedimentary and metamorphic processes. It is located in northeast China, Inner Mongolia, the Yellow Sea, and North Korea. The ...

from at least 1 billion years ago, before breaking off million years ago at the end of the

Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is ...

. 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 m ...

beginning to impact the ancient

shoreline somewhere between 55–35Ma. At first, Qaidam was at a far lower elevation.

Pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

found in

core sample A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The ...

s 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 ...

(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 recent" ...

(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 cr ...

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 The Monsoon of South Asia is among several geographically distributed global monsoons. It affects the Indian subcontinent, where it is one of the oldest and most anticipated weather phenomena and an economically important pattern every year fro ...

. It went from a

forest steppe A forest steppe is a temperate-climate ecotone and habitat type composed of grassland interspersed with areas of woodland or forest. Locations Forest steppe primarily occurs in a belt of forest steppes across northern Eurasia from the easter ...

to a desert. 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 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 finally confirmed ...

(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 interval A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...

s 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 silicates ...

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 Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...

lake. Pollen studies suggest the bed of

Dabusun Lake Dabusun or alternately known as is a lake beside the town Qarhan, just north of Golmud in the Haixi Prefecture of Qinghai Province in northwestern China. Fed by the main course of the Golmud River, it is the largest present-day lake in ...

in the Qarhan Playanearly the lowest point of the basinwas elevated about within the last 500,000 years. At around 30

kya Kya, kya or KYA may also refer to: People or fictional characters * Kya Lau, chef and contestant on ''MasterChef Junior'', season 4 * Kya, mother of Katara and Sokka, in ''Avatar: The Last Airbender'' * Kya, daughter of Aang and Katara in ''The ...

, 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 solid ...

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 c ...

s near

Mount Buka Daban Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish ...

which now feed into the Narin Gol River that flows into East Taijinar Lake. Around 30

, 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 ( D ...

, 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 quanti ...

. 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 crude ...

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 ...

. 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 A refinery is a production facility composed of a group of chemical engineering unit processes and unit operations refining certain materials or converting raw material into products of value. Types of refineries Different types of refineries ar ...

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 Pl ...

, 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 ...

Lanzhou Lanzhou (, ; ) is the capital and largest city of Gansu Province in Northwest China. Located on the banks of the Yellow River, it is a key regional transportation hub, connecting areas further west by rail to the eastern half of the country. H ...

, 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 buil ...

. Qaidam has reserves of asbestos,

borax Borax is a salt (chemistry), salt (ionic compound), a hydration (chemistry), hydrated borate of sodium, with chemical formula often written . It is a colorless crystalline solid, that dissolves in water to make a base (chemistry), basic aqueo ...

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 dr ...

, and several

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typi ...

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 atmosp ...

, 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, the encyclope ...

''
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, succeedi ...

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