Sierras Pampeanas
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The Sierras Pampeanas (also called Central Sierras or Pampas Sierras) (English: Pampas Mountains) is a geographical region of Argentina.
The Sierras Pampeanas are a chain of mountains that rise sharply from the surrounding
Geography
The highest point of the Sierras Pampeanas is
Due to erosion and other geologic forces (volcanoes, glaciers, rivers, tectonic etc.), the surface of this area varies widely. It includes cliffs and narrow channels of some rivers which are named "drawers" (if they are of moderate size) or "guns "(if they are older); there are abundant caves, grottos and overhangs. Some mountains are separated by significant open areas (too large to be considered a "valley"); these are called "barreales" (mud-flats) or "pampas" (grassy plains).
Sub-ranges
The Sierras Pampeanas are composed of several sub-ranges:
- Tucumán and Catamarca: Cumbres Calcahaquíes, Sierra del Aconquija;
- Catamarca: Sierra de Belén, Sierra de Ambato, Sierra de Ancasti (or Sierra del Alto), Sierra de Fiambalá, Sierra de Hualfín;
- La Rioja: Sierra de Famatina, Sierra de Sañogasta, Sierra de Velasco, Sierra de los Llanos, Sierra de los Colorados, Sierra de las Minas, Sierra de Chepes, Sierra de Paganzo;
- San Juan: Sierra de Valle Fértil, Sierra de la Huerta, Sierra Guayaguas, Sierra de Pie de Palo;
- Santiago del Estero: Sierra de Ambargasta, Sierra de Guasayán, Sierra de Sumampa;
- San Luis: Sierra de las Quijadas, Sierra de Varela, Sierra del Portezuelo, Sierra del Alto Pencoso, Sierra del Yulto, Sierras de San Luis, Sierra de Guayaguas, Sierra de Cantantal, Sierra del Tala;
- Córdoba: Sierras de Córdoba, including Sierras de Comechingones (which border with San Luis).
The name "Pampean Ranges" can be misleading, since the Argentine Pampas cover most of the country's northern and eastern portion. However, other mountains which rise from these expanses are considered distinct geologic formations, not part of the Sierras Pampeanas.
Geology
Before the Mesozoic the Sierras Pampeanas was affected by cycles of orogenic events produced by a series continent-continent collisions along the Proto-Pacific margin of
Between 530 and 440 million years ago, during the Pampean and Famatinian orogenies the area of the Sierras Pampeanas was intruded by a series of pegmatite dykes.[2] Later, around 370 million years ago a smaller event of pegmatite intrusion took place.[2] Today these dykes are collectively known as the Pampean Pegmatite Province.[2][3] These pegmatites host valuable lithium reserves.[2]
By the end of the Paleozoic erosion had led to the formation of a peneplain in the eastern Sierras Pampeanas.[4] Later tectonic movements split this surface into various levels with the highest level being Pampa de Achala.[4]
As the South Atlantic opened following the Paraná-Etendeka flood basalts, the Andean orogeny began the formation of the Andes, the product of volcanism and compressional forces along the Pacific margin, but also resulted in the development of extensional basins in South America and a passive margin along the Atlantic coast, processes still going on today. The basement of the Sierras Pampeanas was uplifted during the Andean orogeny over a near-horizontal segment of the subducting Nazca Plate. Sierras Pampeanas was also affected by Miocene arc magmatism 700 km (430 mi) east of the Chile Trench during this period.[1]
Climate and hydrography
This region has a temperate and semi-arid climate, with warm summers and cool winters. The northern east slope is covered by rainforest, due to high humidity in this subtropical zone. The portions within Córdoba and San Luis enjoy Mediterranean-type climate, with intense summer rainstorms and snowy winters; the vegetation here includes conifer trees. More precipitation falls on the eastern slopes, which meet the moist winds from the Atlantic Ocean.
Groundwater is not abundant in most of this area; the eastern slopes show greater population due to the greater runoff water available there. There are short, torrential rivers and many streams and rivulets that carry low flows, with brief and violent floods caused by summer rains. These rivers are used for the production of hydropower.
Flora and fauna
The flora and fauna of the Sierras Pampeanas varies with elevation and exposure. The
Flora
Extant species include
In the more arid regions (the west faces) grow giant or medium
The
The Sierras de Córdoba in Córdoba and San Luis provinces have abundant vegetation on the eastern slopes, including carob, "coconuts" (local name of palm trees), garabato blanco (acacia) and willow.
Much of the area is deforested due to desertification, logging ( "clearing"), strip-mining (without resurfacing or replanting), animal overgrazing, and burning to open up areas for grazing.
Fauna
The area boasts a diverse fauna, although several species are moving toward extinction (such as the
.The observed fauna varies according to the combination of three basic natural factors: the arrangement of mountain ranges, altitude and climate. There are important variances of biome in the Pampas Sierras: semi-arid areas, rain-forest areas, and moderately fertile areas covered with natural forests (especially in Córdoba and San Luis). In the arid zone of La Rioja and Catamarca are found vicuña and some alpaca. Earlier in the twentieth century jaguar were found in the rainforests. In the eighteenth century there were sightings of spectacled bears.
The avifauna is diverse and relatively abundant in the higher, mostly arid areas. It includes
Settlers to the region have introduced domestic animals such as horses, donkeys, goats, pigs, cattle and sheep.
Economy
Agriculture is the predominant economic activity in the area. Certain areas are noted for
. Most products are for local consumption. Only where rainfall is more abundant is agricultural output destined for outside sale.Tree crops are grown in the foothills of the Sierras de Córdoba, including
In arid areas such as the center and west of La Rioja and Catamarca, irrigated vines thrive, and large plantations of olive trees, (jujube was brought by Lebanese immigrants and Syrians in early twentieth century), grains, aloe and jojoba.
Most of these products are sold within the region, mainly associated with tourism. Due to its climate and spectacular scenery the Sierras Pampeanas are a major tourist destination in Argentina.
Salt mining is an important industry; the salt beds there are the country's largest, covering some 8400 km2.
References
Notes
- ^ a b Pankhurst & Rapela 1998, pp. 1–5, Table 1, p. 3
- ^ hdl:10810/57221.
- S2CID 233566212.
- ^ a b Beltramonte, C.A. (2007). "Las superficies de erosión en las Sierras Pampeanas de Córdoba: algunas consideraciones sobre su génesis". Revista de la Asociación Geológica Argentina (in Spanish). 62 (3).
- ^ Godoy-Bürki, Ana C.; Ortega-Baes, Pablo; Sajama, Jesús M; Aagesen, Lone (2014). "Conservation priorities in the Southern Central Andes: mismatch between endemism and diversity hotspots in the regional flora". Biodiversity Conservation (2014) 23:81–107 DOI 10.1007/s10531-013-0586-1
Sources
- Pankhurst, R. J.; Rapela, C. W. (1998). "The proto-Andean margin of Gondwana: an introduction" (PDF). Geological Society, London, Special Publications. 142 (1): 1–9. S2CID 130624944. Retrieved 17 December 2017.