INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Maastrichtian and Danian palynologic records in northwestern Argentina. Biostratigraphic indicators
LLORENS, M.; NARVAEZ, PAULA L.; PEREZ LOINAZE, V.S.
Salvador de Bahia
Congreso; XIV International Palynological Congress and X International Organisation of Palaeobotany Conference; 2016
The Salta Group contains Lower Cretaceous to Paleogene sediments that filled a rift basin developed in northwestern Argentina. The studied palynomorph samples correspond to Maastrichtian and Danian levels from the Yacoraite and Olmedo/Tunal formations respectively. The Yacoraite Formation outcropping at the Tonco river valley (southwestern Salta province), yields a palynoflora containing continental elements represented by angiosperms (52.5%), monilophytes (25.9%), gymnosperms (11.3%; mainly Gnetalean species), bryophytes (2.6%), fungi (2.9%) and algae (4.8%). Taxa like Aquilapollenites magnus and silastephanoporites brasiliensis allow assigning a Maastrichtian age for this association. These pollen grains have also been recorded in associations from Bolivia and Brazil but they do not appear in other Maastrichtian associations from central or southern Argentina (e.g. Jagüel, La Irene, Monte Chico, or Ciénaga del Río Huaco formations). On the other hand, the stratigraphicallyequivalents Olmedo and Tunal formations overly the Yacoraite Formation in different parts of the basin. The samples yielding palynomorphs come from the El Chorro creek (Salta province) and Garabatal localities (Jujuy province). These associations are also characterized by having high percentages of angiosperms (5-(47)-81%; with dominance of the Ulmaceae pollen Verrustephanoporites simplex), monilophyte and bryophyte spores (1-46%), gymnosperms (0.5-6%), and also a high representation of the chlorococcalean green algae Pediastrum spp. (16-92%). The Danian assemblages are included in the Mtchedlishvilia saltenia palynozone characterized by the presence of Mtchedlishvilia saltenia pollen grains associated with Pandaniidites texus and Gemmatricolpites subsphaericus, and they belong to the Ulmaceae phytogeographic province as the Danian Pedro Luro and Salamanca/Bororó formations fromsouthern Argentina. The Maastrichtian and Danian palynologic records presented here are a contribution to future studies of the vegetation changes through the Cretaceous-Paleogene in northern Argentina, and the phytogeographic context.