The 1:5,000,000 map of Argentina contains several important inaccuracies. The main ones are found in extra-Andean Patagonia where the Mesozoic vulcanites are plotted as Precambrian, and the true Precambrian areas are left blank with a question mark. Other notable errors are found in the southern hills of Buenos Aires where the Upper Paleozoic rocks are plotted as Miocene-Pliocene, in the Sierra de Pie de Palo, northeast of San Juan city, where the Precambrian rocks are shown as Cretaceous intrusives, and in the northern half of the “Cordillera” de Famatina where the Paleozoic rocks are marked Jurassic volcanics. The geologic literature of Argentina is very extensive, and the country is fairly well known in all major respects. The present summary is based mainly on the writer’s personal work in the country, supplemented by a long-standing acquaintance with the pertinent literature. Plate 1 shows three geologic sections across Argentina.
PRECAMBRIAN (epC and pCi)
No unquestionable early Precambrian rocks are known in Argentina; most, if not all, are of late Precambrian age. These are extensively exposed in two main areas: the Pampean Ranges of central Argentina and their continuation in the Eastern Cordilleras of Salta and Jujuy and the Patagonian massif of Rio Negro and Chubut. In addition, Precambrian rocks also crop out in the Precordillera and Frontal Cordillera of western Argentina, in the hills of Buenos Aires province, in the Patagonian Cordillera, in a few places along the coast of Santa Cruz, and in Cape Meredith on the Falkland Islands.