Stable Carbon and Oxygen Isotopes as Environmental Indicators of the Late Pleistocene in El Arenoso, Sonora, Northwest Mexico

Abstract

The paleoenvironment conditions that existed in the Late Pleistocene at the archaeological-paleontological site of El Arenoso, Sonora, NW Mexico, were inferred using the carbon and oxygen stable isotopes from one bison, one mammoth, and thirteen horses as well as the pedological characteristics and the carbon isotopes of calcium carbonates from paleosoil. The values δ 13 C of the bison (-1.4‰), the horses (-2.8‰), and the mammoth (-4.3‰) show that these animals fed mainly on C 4 plants and carbon isotopic values from profile horizons of locality 4Bgk (-3.4‰), 3Ck (-3.4‰), and 2Bgk2 (-5.7‰) indicated the presence of C 3 /C 4 vegetation mixed in El Arenoso. The oxygen isotopic ratios of the bison (-4.3‰), the horses (-2.6‰), and the mammoth (-5.1‰) show that these animals inhabited an arid environment, consistent with the results from the analyses of paleosols.