Paleosol (organic matter and pedogenic carbonates) and paleontological δ13C records applied to the paleoecology of late Pleistocene–Holocene in Mexico

• Published in: Quaternary international 2016-10, Vol.418, p.147-164
• Main Authors: Cruz-y-Cruz, T., Pérez-Crespo, V.A., Pustovoytov, K., Sedov, S., Morales-Puente, P., Tovar-Liceaga, R.E., Arroyo-Cabrales, J., Terrazas-Mata, A., Sánchez-Miranda, G.
• Format: Article
• Language: English
• Subjects: Holocene; Late Pleistocene; Paleoenvironment; Paleosols; Pleistocene megafauna; Stable carbon isotopes
• ISSN: 1040-6182; 1873-4553
• DOI: 10.1016/j.quaint.2015.12.093

Stable isotopes of carbon (δ13C) in terrestrial geological materials (paleosol humus and carbonates) as well as fossil bones (collagen and tooth enamel) are established as highly specific records on paleoenvironmental characteristics. It was assumed that comparing the results of different types of materials on regional or local scales provides more accurate and reliable reconstructions and even opens new aspects of interpretation. This was tested by the comparison of the data obtained from the late Pleistocene paleosols and/or remains of Pleistocene megafauna in various locations in Northwestern Mexico: Sonora (paleosols formed in MIS3, MIS2 and MIS1); Central-Northern Mexico: San Luis Potosi (teeth, corresponding to MIS2 and MIS1); and Central-Southern Mexico: Puebla (paleosols corresponding to MIS3 and MIS2, and teeth associated with these paleosols), and State of Mexico (teeth, corresponding to MIS2). The results of isotopic studies are complemented with other paleoenvironmental proxies. The δ13C values of paleosols of Sonora is −19.8 to −16.95‰ in organic matter, and shows little difference between paleosols and Holocene soils; δ13C values of pedogenic carbonates are −6.4 to −4.52‰. In San Luis Potosí, the δ13C values of paleosol are −12.16‰ in organic matter. In Puebla, they vary from −24.6‰ in paleosols to −15.16‰ in the modern surface soil, pointing to contrasting vegetation change. The δ13C values in fossils range from −10.7 to 1.2‰ in SLP; of −2.73 and −2.93‰ in Puebla; and −6.5 to −1.3‰ in State of Mexico. The δ13C values of paleosols and analysis of megafauna in Northwest and Central-Northern Mexico matched each other, indicating mixed C3–C4 vegetation; while for Central-Southern Mexico, paleosols indicated predominance of C3 plants and megafauna indicated mixed C3–C4 composition. In general, the results indicate that in northern Mexico environmental conditions were slightly wetter than at present, while for the central area there was a large change in the environmental conditions of high humidity in MIS3 and MIS2, with a trend to drier climates in MIS1.