Biogeoarcheological evidence of soil Management in Central Mexico during the late Holocene: A case study from the Cuicuilco site

One of the most significant settlements in the southern Basin of Mexico during the Late Preclassic period was the archaeological site of Cuicuilco, which was inhabited by over 20,000 people. Within this enclosure is La Estela, an andesite monolith positioned on an artificial earthen mound south of the most important building in Cuicuilco. It is currently linked to a 2.50-m-deep pedosediment deposit, on which the second-to-last construction phase of the Great Basement was built. Preliminary studies date its earliest occupation to around 800–600 BCE. This study aims to compare the La Estela infill deposits with the ENAH paleosol, used as a natural reference, to distinguish pedogenetic from anthropogenic signals. The soil samples were analyzed through physical properties, bulk chemical composition, and biogeochemical variables, as a biogeoarchaeological technical framework. The bulk chemical composition delineated discontinuities in both natural soils and La Estela layers. The phosphorus (P) fractionation results confirmed that the La Estela layers are anthropogenic. Unlike natural soils, the profile showed no clear pattern, and the highest concentrations were found in recalcitrant fractions, such as organic phosphorus from hydrochloric acid and sulfuric acid (Po-HCl and H 2 SO 4 ). These results support that P is a key element for identifying ancient settlements and reconstructing past human activities. The analyses conducted in this study suggest that no clear pedogenetic pattern was identified among the variables measured along the La Estela profile, mainly due to the high heterogeneity of the layers. Instead, the profile shows consistently reworked features, reflecting human impact on these deposits.