Iguazú / Iguaçu waterfalls

The Iguazú/Iguaçu waterfalls constitute a set of 275 falls with an average height of 75 meters distributed along a front of almost 2,700 meters. These discharge an average of 1,800,000 l/s into the narrow and deep canyon of the Iguazú river (Salamuni et al., 1998). The “Garganta del Diablo” (Devil’s Throat), the most important fall, is the culmination of this canyon that begins in the Paraná river, on the border between Argentina, Brazil and Paraguay, 18 km downstream from the falls. Fissural basaltic volcanic rocks that spread over the surface some 125 to 115 Ma ago (Lower Cretaceous) dominate the region (Ardolino and Miranda, 2008). These lava flows covered an area of 1,200,000 km2 and accumulated thicknesses of up to 1,500 meters, constituting the largest basaltic lava flow recorded on the planet’s continental crust. Its origin is synchronous with the fragmentation of Gondwana, for which these rocks are also recognized in the western sector of Africa, an intercontinental group known as the Parana-Etendeka volcanic province (Llambías, 2023). In South America, these lavas are known as the Serra Geral Formation. The region is a high, flat plateau that is crossed and incised by several rivers. The channel of some of them, like part of the Paran and the final section of the Iguazu are probably structurally controlled (Ardolino and Miranda, 2008).