RESUMO
Mammal faunas collected from the Uquía Formation at Chucalezna and Esquina Blanca in Jujuy Province, northwest Argentina, are calibrated by potassium-argon age determinations and paleomagnetic polarity data. The sediments range in age from 2.5 million years old to perhaps as young as 1.5 million years, from late Pliocene through early Pleistocene, and correspond in time to late Blancan and early Irvingtonian land mammal age faunas in North America.
RESUMO
An average age of 9.41 million years was obtained from radioisotope (potassium-argon) age determinations of three glass concentrates of a tuff from the upper part of the marine Rionegrense at Punta Cracker in Golfo Nuevo, Argentina. This age correlates with the Tortonian marine stage of Europe and the Chasicoan Land Mammal Age of South America.