The pollen record of Zoko Andi 1 archaeological site: contributions for understanding late Holocene paleoenvironments of the southwestern Pampa and northeastern Patagonia (Argentina)

Abstract

Paleoenvironmental proxies have enabled the reconstruction of late Holocene paleoclimatic and paleoenvironmental conditions in the lower basin of the Colorado River (LBCR), within the eastern Pampa–Patagonia transition (Argentina). However, these reconstructions require refinement and testing through new data. Fossil pollen evidence for the last ca. 1500 cal BP was obtained from the Zoko Andi 1 archaeological site, located in the Espinal phytogeographic province within this transitional region. This study aims to present and analyze the pollen record from the site in order to reconstruct local vegetation dynamics and palaeoenvironmental conditions during the late Holocene, and to contribute to the existing knowledge derived from other proxies in the LBCR. Based on the geomorphological characteristics of the sequence, two archaeological components are distinguished: a lower component (ca. 1350 — 1200 cal BP) associated with an abandoned meander environment, and an upper component (since ca. 700 cal BP) related to aeolian deposition. The pollen assemblages indicate that the lower component was dominated by hydrophytic communities associated with wetland conditions under a semiarid climate. After ca. 700 cal BP, halophytic and subsequently psammophytic communities expanded in association with increasing aeolian activity and dune development, suggesting a progressive trend toward greater aridity, particularly during the last ca. 400 cal BP. This decrease in moisture availability during the final late Holocene has also been documented in nearby regions. Results provide new palaeoenvironmental information and contribute to the reconstruction of late Holocene environmental dynamics and climatic variability in the LBCR and adjacent regions of southwestern Pampas and northeastern Patagonia.