Climatic and vegetational changes inferred from Cenozoic Southern Southamerica paleoflora.

Abstract

A reconstruction of the continental climate of southern South America, based on physiognomic analyses of fifteen taphofloras, coming mainly from Chile and Argentina, is presented here. Based on the climate estimates and the phytogeographical composition of the Cenozoic paleofloras analyzed, the succession of four new Paleofloras is proposed: Gondwanic; Subtropical Gondwanic; Mixed and Subtropical Neogene Paleoflora. The results indicate that these paleofloras are, at least, related with three major paleoclimatic scenarios: 1- Paleocene/Eocene, warm and humid tropical conditions, associated with both Gondwanic and Subtropic Gondwanic Paleofloras; 2- a climate shift towards temperate-drier conditions at the end of the Eocene and early Oligocene, related with the cold global event of the Eocene-Oligocene boundary (as a consequence of the onset of Antarctic glaciation). Time where Mixed Paleofloras dominated, and 3- finally, a warm and humid event again occurred during the Miocene, during this time, mean annual temperature was 6-9°C warmer than for the previous period. This warm event is related with the mid Miocene climatic optimum and it is characterized by the development of Neogene Subtropical Paleoflora.