Misplaced Pages

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29-722: The railway crosses the Qaidam Basin , the Altyn-Tagh mountain range, and the Taklamakan Desert . As the third rail artery linking Xinjiang with neighboring provinces, the line cut travel time between the two places from 26 hours to 12 hours. The railway generally follows the route of Qinghai Provincial Highway 303 (from Golmud to Mangya Lake 茫崖湖), China National Highway 315 (from Mangya Lake to Ruoqiang ) and China National Highway 218 (from Ruoqiang to Korla). A 24.6 km (15.3 mi) long viaduct crosses over

58-533: A forest steppe to a desert . By 12   Ma, the climate had dried enough to break Qaidam's single lake into separate basins, which frequently became saline. During the Pliocene (5–2.5   Ma), the focus of most sedimentation was at what is now Kunteyi but, during the Pleistocene (after 2.5   Ma), tectonic activity shifted the basin's tributaries and floor, moving the focus of sedimentation from

87-504: A kind of shelf between Tibet to the south (around 4,300 m or 14,000 ft) and Gansu to the north (around 1,100 m or 3,500 ft). 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 2–4 °C (36–39 °F) despite lying on the same latitude as Algeria , Greece , and Virginia in

116-612: Is a variant romanization of the same name. Chaidamu is the pinyin romanization of its transcription into Chinese characters ; the same name was formerly romanized as the Zaidam Swamp for the Chinese Postal Map . Orographically , the Qaidam Basin is a comparatively low area in the northeastern part of the Qinghai–Tibet Plateau . With an elevation of around 3,000 m (10,000 ft), Qaidam forms

145-554: Is controlled by the Altyn Tagh fault constituting the northern basin boundary. 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 . 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

174-616: Is covered by saline lakes and playas . Around one third of the basin, about 35,000 km (14,000 sq mi), is desert. Tshwa'i 'Dam is the Wylie romanization of the Tibetan name ཚྭ འི ་ འདམ ་ , meaning " Salt Marsh "; the Tibetan Pinyin romanization of the same name is Caidam . Qaidam is the GNC romanization of its transcription into Mongolian ; Tsaidam

203-455: The Dalangtan to Qarhan area. During this time, the record's glacial intervals suggest a low-temperature climate and its sandstone 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

232-718: The Earth's equatorial plane . It crosses Europe , the Mediterranean Sea , Africa , Asia , the Pacific Ocean , North America , and the Atlantic Ocean . At this latitude the Sun is visible for 14 hours, 42 minutes during the summer solstice and 9 hours, 37 minutes during the winter solstice . The 37th parallel north is roughly the northern limit of the visibility of Canopus , the second-brightest star of

261-662: The Four Corners at the intersection with the 32nd meridian west from Washington (the only place where four U.S. states meet at a point); Cairo, Illinois ; Bowling Green, Kentucky ; and Newport News, and Hampton, Virginia . It enters the Chesapeake Bay at the northernmost tunnel entrance / exit of the Hampton Roads Bridge Tunnel and the southernmost point of Old Point Comfort on the former Army base, Ft. Monroe. The parallel 37° north formed

290-592: 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. 37°16′N 94°27′E  /  37.267°N 94.450°E  / 37.267; 94.450 37%C2%B0 N Download coordinates as: The 37th parallel north is a circle of latitude that is 37 degrees north of

319-905: The Karakoshun Lake . The line is used for passenger travel and cargo such as petroleum products . Combined with the Hotan–Ruoqiang railway along the southern rim of the Tarim Basin (which opened on June 16 2022), the Kashgar–Hotan railway , the Korla–Kashgar section of the Southern Xinjiang railway, and the Ruoqiang –Korla section of the Golmud–Korla railway, railways now form a 2,712 km (1,685 mi) loop around

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348-490: The Miocene (23–5   Ma), this lake spread at the present 2,800 m (9,200 ft) elevation contour over 300 km (190 mi) and was among the largest lakes in the world . Nutrient-rich inflows contributed to plankton 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

377-465: The Tarim Basin . With a design speed of 120 kilometres per hour (75 mph), the Qinghai section of the rail route launched on 30 June 2020 stretching 506.5 kilometres (314.7 mi) and 15 stations, with one pair of passenger trains and two pairs of freight trains per day at launch. The remaining section opened on 9 December 2020. On 11 October 2021, service frequency between Golmud and Mangyazhen

406-657: 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 . Because of this position, Qaidam forms an endorheic basin accumulating lakes with no outlet to

435-677: The United States . The crescent-shaped basin covers an area of approximately 120,000 km (46,000 sq mi). 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

464-635: The Huatugou field with a major refinery at Golmud , and the Sebei gas fields are connected to Xining , Lanzhou , and Yinchuan . Qaidam has reserves of asbestos , borax , gypsum , and several metals , with the greatest reserves of lithium , magnesium , potassium , and sodium found anywhere in China. The Xining-Golmud rail line (the first stage of the Qinghai–Tibet Railway ), which crossed

493-541: 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 and 306.6 billion cubic meters (10.83 trillion cubic feet) of natural gas . Annual production capacity is about 2 million metric tons of petroleum and 8.5 billion cubic meters of natural gas. A pipeline connects

522-472: The Qarhan Playa—nearly the lowest point of the basin—was elevated about 700 m (2,300 ft) within the last 500,000 years. At around 30 kya , this great—at the time, freshwater—lake spread over at least 25,000 km (9,700 sq mi) with a surface 50–60 m (160–200 ft) above the present levels of its successors. At the same time, a river from the "Kunlun" paleolake to its south

551-517: 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 as deep as 10 to 14 km (6–9   mi) in places despite tectonic activity having repeatedly shifted the center of the region's sedimentation. The seasonal nature and commercial exploitation of some of

580-638: The beginning of the Cenozoic , with the Indian Plate beginning to impact the ancient Tibetan shoreline somewhere between 55 –35   Ma. At first, Qaidam was at a far lower elevation. Pollen found in core samples shows that the Oligocene (34–23   Ma) 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

609-694: The creation of the Cherokee Strip . Congress extended the line west to New Mexico Territory , thus defining which states and territories would constitute The South between the Colorado and Mississippi Rivers, and creating what later became the Oklahoma Panhandle . Landmarks on the 37th parallel include Santa Cruz, California ; Gilroy, California ; Madera, California ; Ubehebe Crater in Death Valley ; Colorado City, Arizona ;

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638-526: 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

667-552: 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 16,509 km (6,374 sq mi). 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 analogue for use in testing spectroscopy and equipment for China's 2020 Mars rover program . Qaidam

696-466: The night sky. Along with the 37th parallel south , it is the latitude at which solar irradiance is closest to the planetary average, with higher solar irradiance equatorward and lower poleward. Starting at the Prime Meridian and heading eastward, the parallel 37° north passes through: In the United States , the parallel defines the southern borders of Utah , Colorado , and Kansas , and

725-534: The northern borders of Arizona , New Mexico , and Oklahoma . It dates to the Kansas–Nebraska Act of 1854 when Congress divided Unorganized Territory into Kansas and Nebraska north of the 37th parallel and a remainder Indian Territory to the south. Before that, the line had been thought to be the boundary between the Cherokee and Osage reservations – the 2.46 miles (3.96 km) discrepancy resulting in

754-412: 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 26 mm (1 in) but the mean annual evaporation is 3,000–3,200 mm (120–130 in). Because of the low rainfall, these lakes have become saline or dried up completely. Presently, there are four main playas in

783-670: Was enriching the Sanhu region with enormous reserves of lithium derived from hot springs 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

812-573: Was increased to one train in each direction per day. This People's Republic of China rail-related article is a stub . You can help Misplaced Pages by expanding it . Qaidam Basin 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 120,000 km (46,000 sq mi), one-fourth of which

841-543: Was part of the North China Craton from at least 1 billion years ago, before breaking off c.  560 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 200   Ma. Three-dimensional modeling shows that the present basin has been squeezed to an irregular diamond shape since

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