The role of pedogenesis in palaeosols of Mexico basin and its implication in the paleoenvironmental reconstruction

摘要

Most of the paleoenvironmental information for the Basin of Mexico comes from sedimentary proxies, which unfortunately are incomplete for the terminal Pleistocene and the Holocene. In this paper, we present a temporal and spatial reconstruction of past soil cover in the south and north of the Basin of Mexico, during the MIS 2 and 1 (Marine Isotope Stage 2 and 1). Palaeosol profiles were selected from three locations (Cuicuilco, Copilco, and Avon) in the south basin, and compared with soils studied in the Teotihuacan valley, Pachuca, and Texcoco at north of the basin. The results show that the Pleistocene soil cover is more homogeneous, dominated by the presence of Luvisol type soils with secondary carbonates, dated to around 20,000 cal yr BP. During the Holocene, the soil distribution changes, with Andosols developing in the south while Vertisols and Calcisols form in the north. The new soil distribution reflects differing climate conditions during the Holocene, conditions which characterize the basin today. The Andosol cover in south basin, however, represents the result of short term pedogenesis; Andosols are considered high quality soils that were attractive to settlers and were a factor in the development of sedentary villages.