Bioestratigrafía basada en quistes de dinoflagelados de la Formación Cabo Peña (Eoceno terminal- Oligoceno temprano), Tierra del Fuego, Argentina

Abstract

In this paper we describe the lithostratigraphy and biostratigraphy of the Cabo Peña Formation in its type area of northern Tierra del Fuego. The Cabo Peña Formation consists mainly of siltstones passing upwards into silty sandstones.These are overlain by conglomeratic sandstones at Cabo Peñas and by coarse-grained sandstones at Cerro Águila. Abundant and diverse assemblages of dinoflagellate cysts (dinocysts) characterize both sections, allowing age and paleoenvironmental interpretations to be made.Selected dinoflagellate cyst events indicate a latest Eocene age for the lowermost part and an age no younger than early Oligocene near the top of the Cabo Peña Formation in both sections. Assemblages from the lower part of the formation are dominated by Nematosphaeropsis lemniscata and Impagidinium spp., suggesting an oceanic to outer neritic environment.In the upper part of the two sections, palynological residues are dominated by pollen and terrestrial spores, and the dinocyst assemblages reflect a neritic rather than fully oceanic environment.Gelatia inflata, Deflandrea spp. indicate cool surface waters rich in dissolved nutrients.