Late Holocene depositional environments of Lake Coatetelco in Central-Southern Mexico and comparison with cultural transitions at Xochicalco

Abstract

Late Holocene depositional environments of the Lake Coatetelco, with a volcaniclastic watershed, were evaluated with respect to cultural transitions in the nearby archeological site at Xochicalco in order to explore the relationship between hydroclimate and evolution of one of the important Mesoamerican cultures in central-southern Mexico. Several high-energy runoff events between ca. 2576 and 2232 cal yr BP (627–283 BCE) represented unstable watershed in an overall humid hydroclimate during the Pre-Classic Period. More silt and clay of ca. 1258–1006 cal yr BP (665–944 CE) were contemporary with flourishing of religious and political center on the Xochicalco Hills during the Epiclassic Period. Anthropogenic perturbations over this interval led to depositional hiatus and caused alterations in sediment composition and chronology. Deposition of authigenic calcite between ca. 1006 and 854 cal yr BP (944–1096 CE) suggested droughts over earlier part of the Post-Classic Period, and aeolian activity of this interval possibly transported fine sand into the lake. Our observation of dry conditions, coeval with abandonment at Xochicalco, contributes additional data during the demise of a vital pre-Columbian center in Mesoamerica. This arid hydroclimate occurred simultaneously as the ENSO became stronger, and the conditions improved post ca. 854 cal yr BP (>1096 CE) with an unstable paleohydrology during the latter part of the Post-Classic Period.