Chaco Basin
Cuenca Chaco, Cuenca Chaco Paranaense
Location of the basin in South America
Coordinates	25°S 60°W / 25°S 60°W / -25; -60
Etymology	Chaco
Location	Central South America
Region	Gran Chaco  Paraná Basin
Country	Argentina  Bolivia  Paraguay
State(s)	Chaco, Formosa Chuquisaca, Santa Cruz, Tarija Alto Paraguay, Boquerón
Cities	Filadelfia
Characteristics
On/Offshore	Onshore
Boundaries	Andes
Part of	Andean foreland basins
Hydrology
River(s)	Paraguay, Paraná
Geology
Basin type	Foreland basin
Orogeny	Andean
Age	Paleozoic-Holocene
Stratigraphy	Stratigraphy

The Chaco Basin (Spanish: Cuenca Chaco, Spanish: Cuenca Chaco Paranaense or Spanish: Cuenca Chaco-Paraná) is a major sedimentary basin in Central South America around the borders of Argentina, Bolivia and Paraguay. The basin forms part of the larger Paraná Basin. Superficially, the Chaco Basin is an alluvial basin composed of land-derived (in contrast to marine sediments) material, mostly fine sand and clays of Paleogene, Neogene and Quaternary age. On deeper levels the Paraguayan Chaco is made up by four sub-basins, the Pirizal, Pilar, Carandaity and Curupaity basins.^[1][2]

Stratigraphy

The basin is part of the megaregional Paraná Basin, of which it occupies its western portion. The basin is subdivided into the Western Chaco (Chaco Occidental) and Eastern Chaco (Chaco Oriental). The Paleozoic stratigraphy of the Chaco Basin comprises the Middle to Late Carboniferous Sachayoj Formation, the Late Carboniferous Charata Formation and the Early Permian Chacabuco Formation.^[3] The Neogene cover contains the Late Miocene Paraná Formation,^[4] the Late Pleistocene (Lujanian in the SALMA classification) Chaco Formation,^[5][6] also described as Eocene to Miocene,^[7] and the substratum-forming Fortín Tres Pozos Formation in the Formosa Province of northern Argentina.^[8][9]

References