Climatic conditions during interglacial and glacial phases in Argentine Pampas based on stable isotope analysis of fossil mammals

Abstract

Profound climatic changes, related to the alternation of glacial and interglacial periods, took place during the Pleistocene. We have evaluated the variability of mean annual precipitation (MAP) and mean annual temperature (MAT) in the Argentine Pampas (La Pampa and Buenos Aires Provinces) during three phases: Last Interglacial (LIG, ~125,000 calBP); Last Glacial Maximum (LGM, 28,170-19,849 calBP) and post-Last Glacial Maximum (post-LGM, 17,281-11,500 calBP). The estimation of these parameters was based on tooth enamel δ13C and δ18O isotopic data of equids and cervids from nine fossil sites. During the LIG, we calculated a MAT of 15.9°C but MAP could not be estimated. In the LGM, a MAT of 14.8°C and a MAP of 552 mm were calculated. During the post-LGM, we calculated a MAT value range from 14.6 to 17.0°C and MAP from 480 to 1,229 mm. Variability of post-LGM localities parameters may be due to the alternation of warm (e.g. Bølling-Allerød) and cold (e.g. Younger Dryas) events. Changes identified seem to be controlled by alterations in atmospheric circulation. Thanks to current atmospheric circulation models and theestimated MAT and MAP of each phase, we propose differential atmospheric scenarios that explain such climatic changes across the Late Pleistocene.