Does the Río Turbio Formation preserve evidence of an extinct biome?

FERNÁNDEZ, D.; BARREDA, V.D.; PALAZZESI, L; JARAMILLO, C.

Salvador

Congreso; XIV International Palynological Congress ? X International Organisation of Palaeobotany Conference; 2016

XIV International Palynological Congress ? X International Organisation of Palaeobotany Conference

The Rio Turbio Formation (RTF) was accumulated in the Austral Basin, Patagonia, during the early MiddleEocene to the Late Eocene. The RTF preserved a unique paleoflora known as the ?Mixed Paleoflora (MP)?,a flora that by the middle Eocene occupied most of temperate South America. The MP lived under a uniquecombination of climatic parameters including a temperate region with a relatively warm winter, high annualprecipitation, little seasonal variation, representing a climate that has not a modern analogue. The MP had amixture of angiosperms and gymnosperms that combined Neotropical elements, cold-temperate elementsfrom Gondwana?sub-Antarctic in origin?and in situ Chaco forests. Is the MP a biome with no modernanalog? In order to answer this question, we studied 22 palynological samples from nine sections of theEocene in Patagonia. We compared the palynological assemblages with most of the extant biomes temperateSouth America. We used the pollen data from the Latin American Pollen Database and perform a similarityanalysis using the Chao?s similarity index. Preliminary results show that the MP of the upper member ofthe RTF have a greater similarity to the extant Valdivian Forest. In contrast, The MP of the lower member ofthe RTF is not similar to any extant biome. We aim to expand the analysis to include additional GondwananEocene floras of Brazil, Chile, Bolivia, Australia and New Zealand.