Fossil pollen records indicate that Patagonian desertification was not solely a consequence of Andean uplift

PALAZZESI, L; BARREDA, V.D.; CUITIÑO, J.I.; GULER, M.V.; TELLERÍA, M.C.; VENTURA SANTOS, R.

NATURE COMMUNICATIONS

Macmillan Publishers Limited.

Año: 2014 vol. 5 p. 1 - 8

2041-1723

The Patagonian steppe?a massive rain-shadow on the lee side of the southern Andes?is assumed to have evolved B15?12 Myr as a consequence of the southern Andean uplift. However, fossil evidence supporting this assumption is limited. Here we quantitatively estimate climatic conditions and plant richness for the interval B10?6 Myr based on the study and bioclimatic analysis of terrestrially derived spore?pollen assemblages preserved in well-constrained Patagonian marine deposits. Our analyses indicate a mesothermal climate, with mean temperatures of the coldest quarter between 11.4 !C and 16.9 !C (presently B3.5 !C) and annual precipitation rarely below 661mm (presently B200 mm). Rarefied richness reveals a significantly more diverse flora during the late Miocene than today at the same latitude but comparable with that approximately 2,000 km further northeast at mid-latitudes on the Brazilian coast. We infer that the Patagonian desertification was not solely a consequence of the Andean uplift as previously insinuated.