Six U–Pb ages between c. 279 and 253 Ma were obtained from the Choiyoi magmatism in Argentine Frontal Cordillera.
Three stages of magmatism are identified in the evolution of the Late Paleozoic to Triassic, southwestern Gondwana margin.
These stages are named pre-Choiyoi, Choiyoi (286–247 Ma) and post-Choiyoi magmatism, and their characteristics are given.
The Paganzo basin registers only the pre-Choiyoi magmatism, and the Sauce Grande basin only the Choiyoi magmatism.
The Paraná and Karoo basins register both the pre-Choiyoi and Choiyoi magmatism.