Abstract

ROJO, Leandro David  and  ZAVATTIERI, Ana María. Microfloristic study of the Potrerillos and Cacheuta Formations (Triassic) southern Cacheuta hill, Mendoza, Argentina. Part 1. Ameghiniana [online]. 2005, vol.42, n.1, pp.3-20. ISSN 1851-8044.

At two outcropping sections, south of the Cacheuta hill, Mendoza province, in the Triassic clastic sediments of the Potrerillos and Cacheuta formations, 85 species of spores, pollen grains and chlorococcales algae were identified. In this first part the geologic context is briefly considered and the continental fluvial/lacustrine paleoenvironmental interpretation for both units is based on earlier sedimentologic study. The stratigraphic position of the classic plant levels and previously known microfossil flora from the "Minas de Petroleo", Cacheuta hill, is analized and relocated. In this first contribution thirty eight species of bryophyte and pteridophyte spores from both palynofloras are listed and illustrated, from which those species registered for the first time for both formations and for the Triassic of Argentina and those of chronostratigraphic importance are described systematicaly. Ten species belonging to the genera Anapiculatisporites , Antulsporites , Clavatisporites , Densoisporites , Foveosporites , Matonisporites , Neoraistrickia , Raistrickia , Rugulatisporites and Uvaesporites are new records for the Triassic of the Cuyo Basin. The known botanical affinities of the miospores are presented and compared with the local megaflora species. The taxonomic diversity is represented by 38 species of spores versus 13 species of bryophyte and pteridophyte plant remains known from the megaflora, thus the microfloristic biodiversity is larger than the megafloristic one.

Keywords : Palynology; Potrerillos and Cacheuta Formations; Triassic; Mendoza; Argentina.