Palynostratigraphy and paleoenvironments of Early Jurassic strata (Nestares Formation) in northern Patagonia, Argentina. Part 1. Terrestrial species

ZAVATTIERI, A.M. & VOLKHEIMER, W.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2003 vol. 40 p. 545 - 558

0002-7014

A palynological analysis is presented of the Early Jurassic Nestares Formation at its type locality, on both sides of the Limay river, Alicura dam, at Neququen nad Rio Negro provinces boundary, northern Patagonia, Argentina. In this first part the terrestrial species (spores and pollen grains) of the microflora are listed, illustrated and, in some cases, commented on. The geological context is reviewed and different paleoenvironmental interpretations, one as a paralic sequence and another as an anastomosing fluvial systems, both based on earliest sedimentological studies, are considered. The microflora is compared with the known record of the megaflora and the botanical affinities of the components of the microflora are proposed. Thirty nine of the species of the miospores illustrated and listed are recorded for the first time in the Early Jurassic of Argentina. The terrestrial taxonomic diversity is represented by 48 species of Bryophyte and Pteridophyte spores and 23 of Gymnospermous pollen grains, versus five species of Pteridophytes and 17 Gymnosperm species known from the megaflora; thus the microfloristic biodiverty record is larger than the megafloristic one.