Chaco Basin
Chaco Basin, also called Cuenca Chaco or Cuenca Chaco-Paraná, is a large sediment-filled basin in central South America, around the borders of Argentina, Bolivia and Paraguay. It is the western part of the Paraná Basin and lies on land in the Gran Chaco region. The basin is split into Western Chaco and Eastern Chaco, and in Paraguay it contains four sub-basins: Pirizal, Pilar, Carandaity and Curupaity.
Geology: The Chaco Basin is mainly an alluvial, river-fed basin with layers of fine sand and clay deposited from the Paleogene to today. Deeper rocks include Paleozoic formations such as Sachayoj (Middle–Late Carboniferous), Charata (Late Carboniferous), and Chacabuco (Early Permian). The Neogene cover includes formations like Paraná (Late Miocene) and the Chaco Formation (Late Pleistocene), with the Fortín Tres Pozos Formation found in Formosa Province.
Hydrology: The basin is drained by the Paraguay and Paraná rivers.
Age: Sediments span from the Paleozoic to the Holocene.
This page was last edited on 3 February 2026, at 11:02 (CET).