Resumo

BAEZ, Alejandro D et al. Análisis sedimentológico de depósitos lacustres y eólicos del cretácico tardío en la localidad Paso Córdoba, cuenca Neuquina. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.4, pp.459-471. ISSN 0004-4822.

The Late Cretaceous sedimentary rocks of the Anacleto and Allen Formations in the area of Paso Córdoba comprise lacustrine and eolian deposits. Lacustrine systems are represented by offshore and shoreface deposits, with associated deltaic systems. Offshore deposits are composed of mudstones with abundant mica content, organic matter, and Corbicula molds. Shoreface facies shows tabular banks of fine-grained sandstones, bioturbated by suspension feeders (Skolithos, Arenicolites) and ornamented burrows (Spongeliomorpha), and subordinately tabular banks with high concentration of fragmented bioclasts produced by storm events. The deltaic systems shows the typical upward-coarsening arrangement, generated by the progradation of medium to fine-grained sandstones of the delta-front, bioturbated by Skolithos and Arenicolites, on the heterolitic deposits of the prodelta. Eolian deposits are represented by dunes and dry and wet interdunes. Dune systems are composed by sets up to 10 m thick, integrated by fine to medium-grained sandstones with large scale planar and tangential cross stratification, which laterally pass to dry interdune deposits with vertebrate traces and root marks. The wet interdune facies form lenticular bodies of small regional extension, composed by heterolitic facies bioturbated by Taenidium, Skolithos, Arenicolites, vertebrate traces and root marks. The analyzed section shows a marked aridity from base to top, where the lacustrine system with the Skolithos and Scoyenia ichnofacies (Anacleto Formation) passes transitionally into a wet interdune system with Skolithos and Scoyenia ichnofacies, and to dunes and dry interdunes with the Entradichnus ichnofacies (Allen Formation).

Palavras-chave : Neuquén Basin; Anacleto Formation; Allen Formation; Lacustrine; Eolian; Bioturbation.

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