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Magallanes or Austral Basin
Magallanes or Austral Basin
Cuenca de Magallanes, Cuenca Austral
Coordinates	53°00′S 69°30′W / 53.000°S 69.500°W
Etymology	Strait of Magellan; Austral = "south"
Location	Southern South America
Region	Patagonia
Country	Argentina; Chile
State(s)	Santa Cruz Province; Aysén & Magallanes Regions
Cities	Punta Arenas; Ushuaia
Characteristics
On/Offshore	Both
Boundaries	Andes, Río Chico-Dungeness High
Part of	Andean foreland basins
Area	170,000–200,000 km2 (66,000–77,000 sq mi)
Hydrology
Sea(s)	Southern Atlantic Ocean
River(s)	Shehuén River
Lake(s)	Viedma, Cardiel, Argentino, Pueyrredón, Fontana
Geology
Basin type	Foreland basin
Orogeny	Andean
Age	Jurassic-Holocene
Stratigraphy	Stratigraphy
Field(s)	Chilean coal

The Magallanes Basin^[A] or Austral Basin^[B] is a major sedimentary basin in southern Patagonia. The basin covers a surface of about 170,000 to 200,000 square kilometres (66,000 to 77,000 sq mi) and has a NNW-SSE oriented shape.^[1]^[2] The basin is bounded to the west by the Andes mountains and is separated from the Malvinas Basin to the east by the Río Chico-Dungeness High.^[1] The basin evolved from being an extensional back-arc basin in the Mesozoic to being a compressional foreland basin in the Cenozoic.^[3] Rocks within the basin are Jurassic in age and include the Cerro Toro Formation.^[4] Three ages of the SALMA classification are defined in the basin; the Early Miocene Santacrucian from the Santa Cruz Formation and Friasian from the Río Frías Formation and the Pleistocene Ensenadan from the La Ensenada Formation.

The Magallanes Basin contains most of Chile's coal reserves dwarfing those found in the Arauco Basin or around Valdivia (e.g. Catamutún, Mulpún). Its coals are lignitic to sub-bituminous.^[5]

Stratigraphy

Aysén Basin

The northwesternmost reaches of the basin form a sub-basin known as Aysén Basin or Río Mayo Embayment. From top to bottom the fill the basin is:^[6]

Río Frías Formation (Friasian)
Río Baguales Formation (Deseadan)
Late Cretaceous volcanic rock
Divisadero Group (Aptian to Albian)
Coihaique Group (Late Jurassic to Aptian)
Ibáñez Formation

Northwestern basin

In the Argentinian parts of the basin, the following formations have been registered from north to south:^[7]

Santa Cruz Formation (Santacrucian)
Cerro Boleadoras Formation (Santacrucian)
Río Jeinemeni Formation (Colhuehuapian)
Monte León Formation (Deseadan to Colhuehuapian)
San Julián Formation (Late Eocene to Early Miocene)
Campo Bola Formation
Asunción Formation
Cardiel Formation (Maastrichtian)
Mata Amarilla Formation (Albian to Santonian)
Piedra Clavada Formation (Albian)
Kachaike Formation (Aptian to Cenomanian)
Río Tarde Formation
Apeleg Formation
Cerro Toro Formation (Turonian)
Divisadero Group (Aptian to Albian)
Río Belgrano Formation (Barremian to Aptian)
Springhill Formation (Valanginian to Hauterivian)
El Tranquilo Group (Late Triassic)
- Laguna Colorada Formation (Norian)

South-central basin

La Ensenada Formation (Ensenadan)
Cordillera Chica Formation
Pinturas Formation (Santacrucian)
Santa Cruz Formation (Santacrucian)
Centinela Formation (Middle Eocene)
Río Leona Formation
Río Guillero Formation
Man Aike Formation (Middle Eocene)
Río Turbio Formation (Early to Late Eocene)
Calafate Formation
Cerro Dorotea Formation
Chorrillo Formation (Maastrichtian)
La Irene Formation (Maastrichtian)
Monte Chico Formation (Maastrichtian)
Cerro Fortaleza Formation (Cenomanian)
Anita Formation
Cerro Cazador Formation (Campanian to Maastrichtian)
Alta Vista Formation (Early to Middle Campanian)
Lago Sofía Formation
Cerro Toro Formation (Turonian to Santonian)
Río Mayer Formation (early Hauterivian to early Albian)
Zapata Formation (Berriasian to Hauterivian)
Springhill Formation (Berriasian to Barremian)
Tobífera Formation (Late Jurassic)

Tierra del Fuego

Notes

^ Chiefly used in Chile^{[citation needed]}
^ Mainly used in Argentina^{[citation needed]}

References

^ ^a ^b Gallardo, Rocío E. (2014). "Seismic sequence stratigraphy of a foreland unit inthe [sic] Magallanes-Austral Basin, Dorado Riquelme Block, Chile: Implications for deep-marine reservoirs". Latin American Journal of Sedimentology and Basin Analysis (in Spanish). 1221 (1). Retrieved 7 December 2015.
^ "Cuenca Austral". Secretaría de Energía (in Spanish). Government of Argentina. Retrieved 30 November 2015. De una superficie total de 170.000 Km2, unos 23.000 Km2 pertenecen al área costa afuera.
^ Wilson, T.J. (1991). "Transition from back-arc to foreland basin development in the southernmost Andes: Stratigraphic record from the Ultima Esperanza District, Chile". Geological Society of America Bulletin. 103 (1): 98–111. Bibcode:1991GSAB..103...98W. doi:10.1130/0016-7606(1991)103<0098:tfbatf>2.3.co;2.
^ Fosdick, Julie C. (2007). Late Miocene Exhumation of the Magallanes Basin and sub-Andean fold belt, southern Chile: New constrains from apatite U-Th/He thermochronology. Geological Society of America, Denver Annual Meeting (28–31 October 2007) Paper No. 123-15. Denver.
^ Hackley, Paul C.; Warwick, Peter D.; Alfaro, Guillermo H.; Cuebas, Rosenelsy M. (2006). "World Coal Quality Inventory: Chile" (PDF). World Coal Quality Inventory: South America (Report). USGS. pp. 90–131. Retrieved February 23, 2017.
^ Demant, A.; Suárez, M.; de la Cruz, R.; Bruguier, O (2010). "Early Cretaceous Surtseyan volcanoes of the Baño Nuevo Volcanic Complex (Aysén Basin, Eastern Central Patagonian Cordillera, Chile)". Geologica Acta. 8 (2): 207–219. doi:10.1344/105.000001530 (inactive 1 November 2024).{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
^ Pérez Panera, 2010, p.52

Bibliography

Cretaceous

Pérez Panera, Juan Pablo (2010), Sistemática y bioestratigrafía de los nanofósiles calcáreos del Cretácico del sudeste de la Cuenca Austral, Santa Cruz, Argentina (PhD thesis), Universidad Nacional de La Plata, pp. 1–450