| 词条 | Salar de Punta Negra |
| 释义 |
Salar de Punta Negra is a saltpan in the Antofagasta Region Chile. The saltpan has a surface area of about {{convert|230|km2}} and is surrounded by deposits left by dry valleys that descend the Western Cordillera from mountains such as the Llullaillaco volcano towards the saltpan, but carry water only occasionally. More permanent sources of water in the form of springs also exist at Salar de Punta Negra. In the past at the beginning of the Holocene the area was wetter than today, although the idea that Salar de Punta Negra contained a permanent lake has been disproven. Some early humans moved into the area to exploit the wetlands and left traces in the form of projectile points and archeological sites. Geography and geomorphologyThe Salar de Punta Negra lies in the eastern Antofagasta Region of Chile, which is an important source of copper and nitrate for the country.{{sfn|van Overmeeren|Staal|1976|p=196}} Before 1981 when a large mine opened in the area, access to the region was difficult.{{sfn|Lynch|1986|p=145}} The name refers to a black lava flow on the eastern side of Salar de Punta Negra that was erupted during the Late Pleistocene.{{sfn|Craig|1997|p=65}} The Salar has a surface of {{convert|230|km2}},{{sfn|van Overmeeren|Staal|1976|p=196}} and is a playa with a polygonal clayey-salty surface that is in some places uplifted and occasional canals and ponds filled with saltwater.{{sfn|van Overmeeren|Staal|1976|p=1976}} The salt deposits consist mainly of gypsum, halite and ulexite,{{sfn|van Overmeeren|Staal|1976|p=199}} they form crenulated rims{{sfn|Stoertz|Ericksen|1974|p=40}} and pressure ridges in some points.{{sfn|Stoertz|Ericksen|1974|p=50}} The playa appears to be somewhat asymmetric, down to the northwest, probably a consequence of faulting.{{sfn|Stoertz|Ericksen|1974|p=15}} Salar de Punta Negra lies at the centre of a converging drainage network{{sfn|Craig|1997|p=63}} and is surrounded by a bajada that has an often steep toe where it meets the playa and is itself crisscrossed by channels that originate in dry valleys at the top of the bayada. Of these dry valleys, four of these in the Western Cordillera carry water seasonally{{sfn|van Overmeeren|Staal|1976|p=197}} and are known as Quebrada Zorros, Quebrada Zorritos, Quebrada Tocomar (or Toconar{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=345}}) and Quebrada Llullaillaco. These are often subject to flash floods which occasionally reach the playa surface in the form of mudflows.{{sfn|van Overmeeren|Staal|1976|p=201}} Additional valleys are the Quebrada El Salto and the Quebrada El Salado.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=344}} The Río Frio enters the Salar from the south and gets its water from the Cordillera Domeyko.{{sfn|Lynch|1986|p=148}} Finally, fault-controlled springs such as Barrancas Blancas and water seeps at the eastern margin of Salar de Punta Negra discharge water.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=345}} It is part of a {{convert|77|km}} long and {{convert|30|km}} wide basin between the Western Cordillera with its volcanoes and the Cordillera Domeyko{{sfn|Martínez|Gonzalez|Bascuñan|Arriagada|2018|p=189}} which has formed through tectonic processes in the Mesozoic and Cenozoic{{sfn|Martínez|López|Bascuñan|Arriagada|2018|p=334}} including block faulting and was then filled by Cenozoic deposits.{{sfn|van Overmeeren|Staal|1976|p=197}} In the Western Cordillera, the volcano Llullaillaco reaches a height of {{convert|6725|m}} while the average elevation of the depression amounts to {{convert|3000|m}};{{sfn|van Overmeeren|Staal|1976|p=196}} Llullaillaco is one of the highest volcanoes in the world.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=345}} The basin has a surface area of about {{convert|4263|km2}};{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=208}} to the east of Salar de Punta Negra lie from east over southeast to south the Pampa El Salado, the Pampa San Eulogio and the Pampa del Chino.{{sfn|Martínez|López|Bascuñan|Arriagada|2018|p=337}} Supposed paleolakeIt was supposed that Salar de Punta Negra once contained a large lake, {{convert|55|km}} long, {{convert|20|km}} wide{{sfn|Lynch|1986|p=145}} and {{convert|125|m}} deep at least.{{sfn|Lynch|1986|p=151}} Traces of the former lake such as lacustrine sediments, river deltas, shorelines and lacustrine terraces have been found.[1] During the latest Pleistocene-Holocene, the Quebrada de las Zorras conveyed water from the mountains around Llullaillaco to Salar de Punta Negra.{{sfn|Grosjean|Núñez|Cartajena|2005|p=2}} The lake eventually overflowed first into the Salar de Imilac farther north and then through the Quebrada de Agua Colorada into the Salar de Atacama;{{sfn|Lynch|1986|p=146}} archeological findings have been made in proximity to the overflow pathways.{{sfn|Lynch|1986|p=151}} Later research indicated that there was no firm evidence of such a lake such as either lacustrine sediments{{sfn|Grosjean|Núñez|1994|p=275}} or former shorelines, with supposed shorelines being instead berms formed by subsidence and faults. Likewise, typical fine sediments associated with water are only found on the eastern side of Salar de Punta Negra, where springs are active. The absence of a lake in Salar de Punta Negra is consistent with the fact that paleolakes with clear shorelines in the region only occur at elevations of over {{convert|3500|m}}.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=352}} Farther south, the Salar de Aguas Calientes and the Salar de Pajonales feature clear evidence of former lakes.{{sfn|Lynch|1990|pp=201-202}} GeologyThe Central Andes in Chile consist of five separate geological domains, from east to west these are the Western Cordillera with active volcanoes, the Pre-Andean Depression which contains a number of Tertiary basins such as the Salar de Atacama and the Salar de Punta Negra, the Cordillera de Domeyko, the Central Depression and then the Cordillera de la Costa. With the exception of the Salar de Atacama, the geology of the Pre-Andean Depression is usually poorly known, as most geological research is focused on the eastern side of the Andes where oil reserves are suspected and on the copper-bearing domains of the western Andes.{{sfn|Martínez|Gonzalez|Bascuñan|Arriagada|2018|p=188}} The area is largely covered by Cenozoic sediments and volcanic rocks, but in outcrops a number of older formations can be observed: Devonian-Carboniferous marine deposits (Zorritas Formation), pyroclastic rocks (La Tabla Formation),{{sfn|Martínez|Gonzalez|Bascuñan|Arriagada|2018|p=189}} both of which reach thicknesses of over {{convert|2|km}},{{sfn|Martínez|López|Bascuñan|Arriagada|2018|p=337}} 300-280 million years old plutons, the Triassic sediment-volcanic Sierra Guanaco and the fluvial-lacustrine Sierra de Varas and the marine Rhaetian-Jurassic Profeta Formation.{{sfn|Martínez|Gonzalez|Bascuñan|Arriagada|2018|p=190}} Finally, there are Paleogene deposits of mostly sedimentary or volcanic origin such as the Naranja Formation and the Pampa de Mulas Formation.{{sfn|Martínez|Gonzalez|Bascuñan|Arriagada|2018|pp=190-191}} Large fault systems such as the Escondida-Punta Negra fault delimit the Salar de Punta Negra basin to the west and the east; some eastern faults offset recent deposits.{{sfn|Martínez|López|Bascuñan|Arriagada|2018|p=338}} Climate and biologyThe area has a cold desert climate with average temperatures of {{convert|18|-|8|C}} and average annual rainfall of {{convert|14|mm/year|in/year}}{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=208}}-{{convert|30|mm/year|in/year}};{{sfn|van Overmeeren|Staal|1976|p=196}} precipitation diminishes from {{convert|50|-|150|mm/year|in/year}} in the Western Cordillera to almost zero in the Cordillera Domeyko{{sfn|van Overmeeren|Staal|1976|p=196}} and occurs mostly during the summer months, leading to episodic flows in the dry valleys.{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=208}} Diurnal temperature variation reaches {{convert|30|C-change}}{{sfn|van Overmeeren|Staal|1976|p=196}} and the region is windy, with winds reaching up to {{convert|90|km/h}} and an average of {{convert|14|km/h}}.{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=208}} There is virtually no vegetation close to Salar de Punta Negra today{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=347}} although the little plant life that does exist supports some noctuid moths, including three novel species.[2] The area of Salar de Punta Negra is also frequented by animals such as flamingos. In the past conversely wetlands expanded at Salar de Punta Negra, including grasses, shrubs and sedges. Snail remnants have also been found in the former wetland deposits.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=353}} These wetlands disappeared around 9,700 - 8,100 calibrated radiocarbon years ago.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=355}} Human activityWas the Atacama Desert once considered an obstacle to human habitation, many traces of past human activity have been found in it. Between 12,800 and 9,700 years ago the "Central Andean Pluvial Event" led to the formation of large lakes in the Altiplano and of wetlands in the lowlands; these wetlands acted as oases of life and also as stepping stone for the spread of early humans. During the Holocene the climate became more arid again, the lakes and many of these wetlands disappeared again.[4]{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=207}} The latest Pleistocene-early Holocene was also the time at which humans in South America had colonized all available spaces with various technological strategies,{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=206}} and in the case of the Atacama region this included then existing wetlands.{{sfn|Loyola|Cartajena|Núñez|Patricio López|2018|p=208}} At Salar de Punta Negra, human artifacts have been found at former wetlands and in other sites.{{sfn|Quade|Rech|Betancourt|Latorre|2017|p=355}} At Salar de Punta Negra humans continued to be active even after the drying of the climate, with one site close to a waterhole dated to 4,970 - 4,830 calibrated radiocarbon years ago,{{sfn|Grosjean|Núñez|Cartajena|2005|p=5}} although most earlier sites were abandoned. This is consistent with the so-called "archeological silence" of this period in the Salar de Atacama area.{{sfn|Grosjean|Núñez|1994|p=282}} These wetlands included the Salar de Punta Negra as well as the Salar de Imilac, and a number of archeological sites of latest Pleistocene-early Holocene age have been found at Salar de Punta Negra. In these sites furnaces with camelid bones, various types of instruments[4] projectile points occur.{{sfn|Lynch|1986|p=153}} The objects found at Salar de Punta Negra resemble these found at other contemporaneous archeological sites in Peru, Ecuador, Chile and Argentina{{sfn|Lynch|1986|p=155}} and may stem from an Archaic{{sfn|Grosjean|Núñez|1994|p=280}} to pre-Paleo-Indian occupation of the area.{{sfn|Lynch|1986|p=159}} The objects are classified as the so-called "Fell", "Tuina" and "Punta Negra" "traditions".{{sfn|Grosjean|Núñez|Cartajena|2005|p=8}} At Punta Negra, humans were represented by hunter-gatherer populations that used the locally available plants and camelid animals, the tools found are associated with slaughtering and hunting.[6] Other archeological sites in the area include pircas,{{sfn|Lynch|1990|p=214}} rock art{{sfn|Lynch|1990|p=216}} and Inca roads such as the major Inca highway that was built in 1485 to aid in the domination of the territory;{{sfn|Craig|1997|p=65}} for the Inca the region was a source for minerals such as copper, gold and turquoise.{{sfn|Lynch|1990|p=224}} Copper mining has continued into the present-day, associated with groundwater depletion and the drying of remnant wetlands, leading to legal restrictions in 2005 on groundwater exploration. References1. ^1 {{cite journal|last1=Núñez|first1=Lautaro|last2=Grosjean|first2=Martin|last3=Cartajena|first3=Isabel|title=SEQUENTIAL ANALYSIS OF HUMAN OCCUPATION PATTERNS AND RESOURCE USE IN THE ATACAMA DESERT|journal=Chungara, Revista de Antropología Chilena|date=2010|volume=42|issue=2|url=http://www.redalyc.org/html/326/32615600003/|issn=0716-1182}} [1][2][3][4]2. ^1 {{cite journal|last1=Angulo|first1=Andrés O.|last2=Camaño|first2=Andrés|last3=Angulo|first3=Gino A.|title="From freeze with moths": first discovery of a habitat in Andean Salars for noctuid moths|journal=Neotropical Entomology|date=2006|volume=35|issue=4|pages=556–557|doi=10.1590/S1519-566X2006000400020|issn=1519-566X}} 3. ^1 {{cite journal|last1=Clarke|first1=Jonathan D.A.|title=Antiquity of aridity in the Chilean Atacama Desert|journal=Geomorphology|date=January 2006|volume=73|issue=1–2|page=110|doi=10.1016/j.geomorph.2005.06.008|language=en|issn=0169-555X}} 4. ^1 2 {{cite journal|last1=Loyola|first1=Rodrigo|last2=Núñez|first2=Lautaro|last3=Aschero|first3=Carlos|last4=Cartajena|first4=Isabel|title=TECNOLOGÍA LÍTICA DEL PLEISTOCENO FINAL Y LA COLONIZACIÓN DEL SALAR DE PUNTA NEGRA (24,5º S), DESIERTO DE ATACAMA|journal=Estudios Atacameños|date=May 2017|issue=55|pages=5–34|url=https://scielo.conicyt.cl/scielo.php?pid=S0718-10432017005000011&script=sci_arttext|issn=0718-1043}} }} Sources{{refbegin}}
2 : Salt flats of Chile|Archaeological sites in Chile |
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