The Qaidam, Tsaidam, or Chaidamu Basin is a hyperarid basin that occupies a large part of Haixi Prefecture in Qinghai Province, China. 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 In linguistics, romanization is the conversion of text from a different writing system to the Latin script, Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing written text, and tra ...

of the Tibetan name , meaning "

Salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

Marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

"; 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, or simply pinyin, officially the Chinese Phonetic Alphabet, is the most common romanization system for Standard Chinese. ''Hanyu'' () literally means 'Han Chinese, Han language'—that is, the Chinese language—while ''pinyin' ...

of its transcription into

Chinese characters Chinese characters are logographs used Written Chinese, to write the Chinese languages and others from regions historically influenced by Chinese culture. Of the four independently invented writing systems accepted by scholars, they represe ...

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

Geography

Orographically, 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 is a provinces of China, province in Northwestern China. Its capital and largest city is Lanzhou, in the southeastern part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibetan Plateau, Ti ...

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 Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

, and

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. 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 separate it from the higher central section of the Tibetan Plateau. 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 of southeastern

Xinjiang Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...

Because of this position, Qaidam forms an

endorheic basin An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...

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 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 143.1 Mya. ...

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. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

analogue for use in testing

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

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 The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...

. 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, with the Indian Plate beginning to impact the ancient Tibetan shoreline somewhere between 55–35Ma. At first, Qaidam was at a far lower elevation.

Pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

found in core samples shows that the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

(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 epoch (geology), 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 mea ...

(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 that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

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 landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

. 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 (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Kunteyi but, during the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

(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 rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

yardangs 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 , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

derived from

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

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

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

. 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) of

petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...

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

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

. 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 a 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 P ...

, and the Sebei gas fields are connected to Xining, Lanzhou, and

Yinchuan Yinchuan is the capital of the Ningxia, Ningxia Hui Autonomous Region, China, and was the capital of the Tangut people, Tangut-led Western Xia, Western Xia dynasty. It has an area of and a total population of 2,859,074 according to the 2020 C ...

. Qaidam has reserves of asbestos, borax, gypsum, and several

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

s, with the greatest reserves of

magnesium Magnesium is a chemical element; it has Symbol (chemistry), 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 ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

, and

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

found 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. Additional railroads spanning the basin include the Golmud–Dunhuang Railway completed in December 2019 and a 25 km private railway constructed by Zangge Mining Co., Ltd. The National Development and Reform Commission began conducting preliminary planning for the Golmud-Korla Railway in September 2013, which would stretch across the western portion of the Qaidam Basin. Construction began in November 2014 and concluded in 2020.

References

Citations

Bibliography

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External links

"Qaidam"
in the '' Columbia Encyclopedia''
Qaidam Basin Photos
from

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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