Late Pleistocene climatic change in the French Jura (Gigny) recorded in the delta(18)O of phosphate from ungulate tooth enamel
Résumé
Oxygen isotope compositions of phosphate in tooth enamel from large mammals (i.e. horse and red deer) were measured to quantify past mean annual air temperatures and seasonal variations between 145 ka and 33 ka in eastern France. The method is based on interdependent relationships between the delta(18)O of apatite phosphate, environmental waters and air temperatures. Horse (Equus caballus germanicus) and red deer (Cervus elaphus) remains have delta(18)O values that range from 14.2%. to 17.2%., indicating mean air temperatures between 7 degrees C and 13 degrees C. Oxygen isotope time series obtained from two of the six horse teeth show a sinusoidal-like signal that could have been forced by temperature variations of seasonal origin. Intra-tooth oxygen isotope variations reveal that at 145 ka, winters were colder (-7 +/- 2 degrees C) than at present (3 +/- 1 degrees C) while summer temperatures were similar. Winter temperatures mark a well-developed West-East thermal gradient in France of about -9 degrees C, much stronger than the -4 degrees C difference recorded presently. Negative winter temperatures were likely responsible for the extent and duration of the snow cover, thus limiting the food resources available for large ungulates with repercussions for Neanderthal predators. (C) 2011 University of Washington.