BIOESTRATIGRAFÍA DE POLEN Y ESPORAS DE LA FORMACIÓN CHENQUE, OLIGOCENO TARDÍO? - MIOCENO DE LAS PROVINCIAS DE CHUBUT y SANTA CRUZ, PATAGONIA, ARGENTINA

Viviana D. Barreda

Abstract


"Spore-pollen assemblages recovered from the Chenque Formation were analysed. Four informal biostratigraphic zones were defined, viz. lower zone (A), transition zone (T), middle zone (B) and upper zone (C). A Late Oligocene? - Early to Middle? Miocene age is assigned to the Chenque Formation. The Patagonian spore-pollen assemblages are similar to those of Late Oligocene and mainly Miocene age of New Zealand, Australia and Antarctica. Fossil spore-pollen assemblages of tropical America are less similar. Tree pollen of Podocarpaceae, Fagaceae and Araucariaceae is common; it probably developed in higher or more remote lands than most herbaceous and shrub forms. Chenopodiaceae, Ephedraceae, Restionaceae and Sparganiaceae are frequent and may have lived in a coastal-estuarine-saltmarsh environment. These habitats appear to be better developed in the upper part of the Formation (C zone). Other families such as Compositae, Malvaceae, Gramineae, Polygonaceae, Goodeniaceae, Onagraceae, Anacardiaceae, Escalloniaceae and Gunneraceae are present, but in a lower proportion. These spore-pollen assemblages suggest a humid and temperate to warm temperate climate."

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