EGU21-10368, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Climate Variability reconstructed from La Cueva Chica speleothems for the last 13 ka BP: implications for Megafauna in Southern Patagonia, Chile.

Carole Nehme1,8, Dominique Todisco1, Sebastian Breitenbach2, Isabelle Couchoud3, Igor Girault1, Fabiana Martin4, Luis Borrerro5, John Hellstrom6, Rik TJallingi7, and Philippe Claeys8
Carole Nehme et al.
  • 1University of Rouen Normandy, IDEES 6266 CNRS, Geography, Mont Saint Aignan, France (
  • 2Faculty of Engineering and Environment, Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, United-Kingdom.
  • 3Environnements, Dynamiques et Territoires de la Montagne, UMR 5204 CNRS, Université Savoie Mont-Blanc, France
  • 4Centro de Estudios del Hombre Austral, Instituto de la Patagonia, Universidad de Magallanes, Punta Arenas, Chile
  • 5Departamento de Investigaciones Prehistoricas y Arqueológicas (CONICET), Universidad de Buenos Aires, Argentina
  • 6School of Earth Sciences, The University of Melbourne, Australia
  • 7GFZ German Research Centre for Geosciences, 14473, Potsdam, Germany
  • 8Analytical, Environmental and Geo- Chemistry, Vrije Universiteit Brussel, Belgium.

Investigating palaeoclimate records is of major importance for evaluating the impact of past forcing factors on the evolution of ecosystems, megafauna and human dispersal, especially in Southern Patagonia where few records are available. We report on a 40 cm long flowstone core S6, and fragments of flowstone and a stalagmite from Cueva Chica. The samples were radiometrically dated (U-Th & 14C) to construct age-depth models for the proxy profiles (δ13C, δ18O, and chemical composition). The speleothem proxy data are further informed by both petrographic analysis of the flowstone, and monitoring data. The main objectives of this work are to: i) reconstruct past climate variations using geochemical analyses conducted on the speleothems, and ii) assess the palaeoclimatic context of megafauna extinction in the area. The flowstone core S6 grew discontinuously from ~13 ka to ~1 ka with several possible hiatuses at ~10 ka BP, from 5.7 to 3.0 ka BP, and 2.5 to 1.8 ka BP (interpolated ages). Sample S8 grew from 6.8 to 5.8 ka BP and after 1.2 ka BP. Stable isotopes analyzed at sub-centennial resolution show a 3‰ range for δ18O, and more than 14‰ for δ13C, and the isotope ratios covary along the entire record. These changes are likely caused by kinetic fractionation and prior calcite precipitation (PCP), controlled mostly by changes in moisture availability. The sensitivity of the proxies to hydrological changes and PCP is further tested with indicators using μXRF element data. The multiproxy record from Cueva Chica suggests a wet phase from ~13 to 9 ka BP, likely related to strong westerlies in the Southern Hemisphere, preceded by a short dry/cold spell at ~13 ka BP. This early Holocene wet phase was followed by a colder/drier period from 8.5 to 5.8 ka BP, likely related to weaker westerlies, especially during the mid-Holocene. High precipitation and strong westerlies prevailed from 3.0 to 2.5 ka BP and in Medieval times. Our paleoclimate record implies that the presence of extensive megafauna, the development of Nothofagus forest and human arrival, all occurred during a climatically favorable wet/warm period ca. 13 to 9 ka BP, after the Antarctic Cold Reversal. However, the deterioration of the vegetation cover at the Cerro Benitez coinciding with high δ13C values excursions was initiated after ca. 11 ka BP. Previous studies suggest an extinction of major megafauna species (e.g., Mylodon, Smilodon, Panthera onca mesembrina) during this wet/warm period. Such climate-driven changes likely reduced the open ecosystem environment and may have led to local decline of herbivore populations. Later cooling/drying after ca. 9 ka may have contributed to the disappearance of megafauna and other large mamals (e.g., Hippidion Saldiasi).

How to cite: Nehme, C., Todisco, D., Breitenbach, S., Couchoud, I., Girault, I., Martin, F., Borrerro, L., Hellstrom, J., TJallingi, R., and Claeys, P.: Climate Variability reconstructed from La Cueva Chica speleothems for the last 13 ka BP: implications for Megafauna in Southern Patagonia, Chile., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10368,, 2021.


Display file