High-precision late Aptian Pb/U age for the Punta del Barco Formation (Baquero Group), Santa Cruz Province, Argentina

The Baquero Group holds a rich fossil flora including macrofloristic and palynological remains that characterize the Early Cretaceous vegetation of Argentina. The age of the upper part of the Group, known as Punta del Barco Formation, has been a topic of several discussions in the past. The type locality of this stratigraphic unit exposes fossiliferous tuffs together with muddy tuffs and tuffaceous sandstones beds. However, there have been no reliable age constraints for the fossil assemblages. Pb-206/U-238 analyses of zircon crystals yielded an age of 114.67 +/- 0.18 Ma. This age control makes possible an improved analysis and comparison of the floras in the southern region. (C) 2011 Elsevier Ltd. All rights reserved.