La megaflora de la Formación Tupe (Carbonífero Superior-Pérmico Inferior), en la Mina La Delfina, San Juan, Argentina*

Resumen

The flora of the Tupe Formation (Upper Carboniferous-Lower Permian), at La Delfina Mine, San Juan, Argentina. Two plant assemblages from three levels of the Tupe Formation at La Delfina mine, north of Cuesta de Huaco in the San Juan Precordillera are described. The first assemblage occurs at the lower part of the Tupe Formation (levels N1 and N2), and is referred to the NBG (Nothorhacopteris argentinica-Botrychiopsis weissiana-Gynkgophyllum diazii) Biozone, that characterizes the Upper Carboniferous of NW Argentina. The second association was obtained from a third level (N7), 55 m approximately above level N2. It is composed by scarce remains referable with doubts to Kraeuselcladus argentinus Archangelsky, which could suggest the presence of the Uppermost Carboniferous Interval megafloristic Biozone. Sixty meters above this level a fossiliferous marine horizon occurs with elements of the Lower Permian, Tivertonia-Streptorhynchus Biozone. Thus, the Tupe Formation, in the area of the San Juan Precordillera, is referred to the Upper Carboniferous -Lower Permian interval, and the fossiliferous section at La Delfina mine is proposed as a potential stratotype for the carboniferous-Permian boundary.