Geology of Paraguay

[1] East of Paraguay River Precambrian and Early Paleozoic crystalline basement crop out mainly in the heights of Caapucú and Apa.

The geological processes that have shaped Paraguay's bedrock and sedimentary basins are diverse including rifting, marine sedimentation, metamorphism, eruption of flood basalts and alkaline potassic volcanism.

Caapucú High (formerly called Precámbrico Sur and Saliente del Pilar) is the Northwesternmost outcrop of Río de la Plata Craton.

[1] The basin developed during the Paleozoic and the Mesozoic with a sedimentary record comprising rocks from the Ordovician right up to the Cretaceous, thus spanning the time interval between 460 and 66 million years.

The Chaco region that makes up the northwestern half (~60%) of Paraguay is a modern foreland basin[7] that extends into Argentina and Bolivia where it borders the Andean thrust front.

Cretaceous volcanism did also leave small units of sodic alkaline rocks in Misiones Department in southern Paraguay.

Approximate location of Mesoproterozoic (older than 1.3 Ga) cratons in South America and Africa
Serranías de Paraguarí in Paraguarí Department are made of Silurian sandstone of the Misiones Formation and alkaline intrusives of Early Cretaceous age.