Magallanes Basin
Sedimentary basin in Patagonia, South America
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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.
| Magallanes or Austral Basin | |
|---|---|
| Cuenca de Magallanes, Cuenca Austral | |
  | |
| Coordinates | 53°00′S 69°30′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 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)
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
- Irigoyen Formation
- Punta Basílica Formation
- Castillo Formation
- Loreto Formation (Priabonian - Divisaderan to Tinguirirican)
- Cabo Peña Formation
- Tchat Chii Formation
- Cerro Colorado Formation
- Leticia Formation (Bartonian)
- Punta Torcida Formation
- Arroyo Candelaria Formation
- Río Claro Formation
- Policarpo Formation
- Bahía Thetis Formation
- Cabeza de León Formation
- Arroyo Alfa Formation
- Yahgan Formation
- Beauvoir Formation (Albian)
- Nueva Argentina Formation
- Lemaire Formation
- Pampa Rincón Formation (Barremian to Aptian)
- Chon Aike Formation (Middle Jurassic to Berriasian)
See also
Notes
- Chiefly used in Chile[citation needed]
- Mainly used in Argentina[citation needed]