New insights through the palynological record of the Lower Cretaceous Lagarcito Formation, Argentina: Paleoenvironmental implications

Abstract

The palynological content of the Lagarcito Formation at the East of the Sierras de Guayaguas, San Juan province, central-western Argentina, is analyzed. The study of the Albian palynoflora of the Lagarcito Formation at the La Yesera section, Sierras de Guayaguas, allowed the identification of 64 fossil taxa from eighteen productive samples. A detailed botanical assignation of the palynomorphs, and the statistical analysis of the palynoflora, was performed in order to characterize the local and regional plant distribution. Differences in the palynofloristic content of the three lacustrine episodes productive in palynomorphs, were discussed. At the base of the section, ferns and bryophyte spores dominate the palynoflora. The second and third lacustrine episode showed a prevalence of gymnosperms mainly represented by the monosulcate Cycadopites-Monosulcites complex. The freshwater algae corresponding to the aquatic community are abundant through the section. The presence of interstratified gypsum towards the top of each lacustrine episode indicates a drastical reduction in the lacustrine system due to high levels of evaporation. The comparison of the studied microflora with the palynoflora recovered from the La Cantera Formation in the same basin gave evidence of more humid conditions up in the stratigraphic column.