Lower Cretaceous Palynological Associations from central and northern Argentina. Similarities and differences based on quantitative studies

PAULA LILIANA NÁRVAEZ; NATALIA MEGO; MERCEDES B. PRÁMPARO

Otro; 1° Reunión Virtual de Comunicaciones de la Asociación Paleontológica Argentina; 2020

Asociación Paleontológica Argentina

LOWER CRETACEOUS PALYNOLOGICAL ASSOCIATIONS FROM CENTRAL AND NORTHERNARGENTINA: SIMILARITIES AND DIFFERENCES BASED ON QUANTITATIVE STUDIESPAuLA L. nARVÁEz1, nATALiA MEGo1, AnD MERCEDES B. PRÁMPARo11instituto Argentino de nivología Glaciología y Ciencias Ambientales, CCT-ConiCET-Mendoza. Av. Adrián Ruiz Leal s/n, Parque Gral. San Martín,5500 Mendoza, Argentina. pnarvaez@mendoza-conicet.gob.ar; nmego@mendoza-conicet.gob.ar; mprampar@mendoza-conicet.gob.arPalynofloras from the Lagarcito Formation (LF), Albian, San Luis Basin, and the La yesera Formation (LyF), Albian??Cenomanian, Salta Basin, are compared to understand trends in the distribution of plants during the Cretaceous in theregion. The studied localities are Sierra de Guayaguas, San Juan Province (LF) and Valle de Pucará, Salta Province (LyF). inboth assemblages, gymnosperm pollen prevails (reaching 75% in LF and 90% in LyF). Classopollis spp., bisaccates/trisaccates,inaperturates, Cycadopites pollen type, and Ephedripites pollen type, are present. However, in several samples, theCycadopites pollen type reach half of the total counts in LF, while Classopollis make up almost three-quarters of the totalsum in LyF. Freshwater algae (mainly Botryococcus and Leiosphaeridia) characterize the lacustrine episodes (reaching up to90% in LF and 70% in LyF). Fern and bryophyte spores are important components, ranging from 4 to 64% in both units. inthe LF, psilate and sculptured trilete spores are present in similar percentages (4?20%). Cicatricose spores are scarce, neveroverpassing the 4%. on the contrary, in the LyF, pteridophyte species are mostly represented by cicatricose spores (8?54%)and only 1?5% of other taxa. Aquatic ferns (e.g., Marsileaceae and Salviniaceae) are also present in both associations withpercentages of 3?12%. Classopollis is a frequent to abundant component in early Cretaceous palynofloras from Argentina,decreasing in number towards the Campanian?Maastrichtian. Furthermore, high diversification of cicatricose species(Schizaeaceae/Anemiaceae) is observed during the Aptian?Albian, and aquatic ferns became important elements from theAlbian to the end of the Cretaceous.