info:eu-repo/semantics/article
New U–Pb zircon age for the Pennsylvanian in Argentina: Implications in palynostratigraphy and regional stratigraphy
Fecha
2019-06Registro en:
Cesari, Silvia Nelida; Limarino, Carlos Oscar; Spalletti, Luis Antonio; Colombo Piñol, Ferran; Perez Loinaze, Valeria Susana; et al.; New U–Pb zircon age for the Pennsylvanian in Argentina: Implications in palynostratigraphy and regional stratigraphy; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 92; 6-2019; 400-416
0895-9811
CONICET Digital
CONICET
Autor
Cesari, Silvia Nelida
Limarino, Carlos Oscar
Spalletti, Luis Antonio
Colombo Piñol, Ferran
Perez Loinaze, Valeria Susana
Ciccioli, Patricia Lucia
Friedman, Richard
Resumen
A continuous Pennsylvanian succession belonging to the Agua Colorada and De La Cuesta formations is exposed in the Las Angosturas area (Catamarca Province) of the Paganzo Basin. Glacial, postglacial, fluvial and shallow marine deposits are identified and referred to seven stratigraphic stages. The Agua Colorada Formation provides a persistent record of palynological assemblages in the first five stages, which are assigned to the Subzones A and B of the Raistrickia densa/Convolutispora muriornata Biozone. These palynofloras span the late Serpukhovian-Bashkirian interval. The first isotopic age for the basal section of the De La Cuesta Formation was obtained from shallow marine deposits. Zircons from a tuff intercalated with mudstones and sandstones in the marine interval were analyzed by the CA-TIMS technique providing an age of 311.89 ± 0.21 Ma, based on the weighted average of 206 Pb/ 238 U dates. This new age is compared with previous isotopic ages obtained from different successions in the Paganzo Basin, resulting in the youngest known radiometric date, for the Moscovian transgression. Indeed, a late Moscovian age is already known by isotopic dating of the reddish fluvial deposits of the lower section of the Patquía Formation, which overlies the marine transgression in the Huaco area (San Juan Province). The record of this marine flooding surface in reddish strata at Las Angosturas area provides a cautionary note on considering the appearance of red beds as indicators of the onset of continental conditions in the Paganzo Basin.