Primer registro de palinomorfos de edad pérmica en la Formación Río Francia (Paleozoico Superior, San Juan, Argentina)

Abstract

First record of Permian age palynomorphs in the Río Francia Formation (Upper Paleozoic, San Juan, Argentina). The palynological content of the middle and upper section of the Río Francia Formation (Paganzo Basin) is here presented. Two palynological associations referable to DM Biozone (Raistrickia densa-Convolutispora muriornata), dominated by trilete spores and scarce monosaccate pollen grains, were obtained from carbonaceous levels of the middle section of the unit. An association dominated by the bisaccate, monosaccate, striated pollen grains and scarce trilete spores, that between their components outstand the presence of Vittatina costabilis Wilson emend. Tschudy & Kosanke, V. subsaccata Samoilovich emend. Jansonius, V. minima Jansonius, Striatopodocarpites cancellatus (Balme & Hennelly) Hart, S. phaleratus (Balme & Hennelly) Hart, Kraeuselisporites punctatus Jansonius, Barakarites rotatus (Balme & Hennelly) Bhardwaj & Tiwari, Tuberisaccites varius Lele & Makada, Polarisaccites bilaterales Ybert & Marques-Toigo, and regularly preserved grains referable to the genera Lueckisporites, Weylandites, Klausipollenites and Minutosaccus; belong to carbonaceous shales of the upper part of the formation; that would allow to suggest a Cisuralian-Guadalupian age for this association, equivalent to LW Biozone (Lueckisporites-Weylandites), more likely. Río Francia Formation age is considered, from it palynological content, Pennsylvanian-Cisuralian/Guadalupian.