Paleoclimatic and paleoenvironmental changes in the Lagunas de Vilama lake System (Argentinean Altiplano-Puna Plateau, 22°S): The Medieval Climatic Anomaly and the Little Ice Age in the high Andes

SANTAMANS, CARLA D.; CORDOBA, FRANCISCO E.; GONZALO R. TORRES; ACHIM BRAUER; PAULA VIGNONI; R. TJALLINGII; LILIANA C. LUPO

Bariloche

Congreso; Congreso; International Association of Limnogeology and International Paleolimnology Association Joint Meeting; 2022; 2022

IPA Asociación Internacional de Paleolimnología

The Lagunas de Vilama System (4500 m a.s.l; Central Andes) hosts several shallow lakes, which are very sensitive to climate change. The aim of this research is to analyze the climatic and environmental conditions during the last millennium for this region. To address this, we performed sedimentological, geochemical and palynological analyses of the lacustrine record of Lake Pululos. The geochronological framework was defined by combining 14C and 210Pb ages through a Bayesian analysis, obtaining a high-resolution age-depth model for the last 1300 years. The results indicate a period with extreme droughts (AD 720-895) before the Medieval Climatic Anomaly (MCA), characterized by a saline-hypersaline lake and the development of halophytic plant communities (Amaranthaceae-Chenopodiaceae). During the MCA (AD 895-1110), the record suggests slightly wetter conditions with a saline lake and marsh vegetation. In AD 1110, an abrupt shift to wetter conditions occurred that continued with significant fluctuations until AD 1880. From this period, a wet MCA-LittleIce Age (LIA) transition-stage stands out between AD 1110 and 1270, characterized by high lake-levels with freshwater vegetation and macrophytes (Zanichellia, Potamogeton, Myriophyllum). Afterwards, the LIA was established with a dry-phase (AD 1270-1500) marked by a decrease in lake-levels and the presence freshwater vegetation. This was followed by the establishment of a wet-phase of the LIA between AD 1500 and 1880, characterized by an oligotrophic to eutrophic lake. Between AD 1880 and -2017, the record reflects high lake-levels corresponding to the Current Warm Period. However, from 2009 onwards the record shows a change in climatological and environmental conditions towards a decrease in lake-levels, which would reflect the current negative trend of precipitation in the region.These results provide novel data for the Altiplano-Puna Plateau and highlight the potential of Andean lakes to unravel the mechanisms of past changes in the atmospheric circulation of the Central Andes.