Paleosol (organic matter and pedogenic carbonates) and paleontological delta C-13 records applied to the paleoecology of late Pleistocene-Holocene in Mexico

摘要

Stable isotopes of carbon (delta C-13) 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 delta C-13 values of paleosols of Sonora is -19.8 to -16.95 parts per thousand in organic matter, and shows little difference between paleosols and Holocene soils; delta C-13 values of pedogenic carbonates are -6.4 to -4.52 parts per thousand. In San Luis Potosi, the delta C-13 values of paleosol are -12.16 parts per thousand in organic matter. In Puebla, they vary from -24.6 parts per thousand in paleosols to -15.16 parts per thousand in the modern surface soil, pointing to contrasting vegetation change. The delta C-13 values in fossils range from -10.7 to -1.2 parts per thousand in SLP; of -2.73 and -2.93 parts per thousand in Puebla; and -6.5 to -1.3 parts per thousand in State of Mexico.