Holocene Paleoenvironmental Reconstruction at 47° S (Patagonia, Argentina) from Sedimentary Sequences (Fens and Lagoon) and Archaeological Sites: A Regional Synthesis

Abstract

At 47◦ S in Argentine Patagonia, the interaction between the Southern Westerly Winds(SWW) and the Andean barrier generates a steep climatic gradient, providing an idealsetting to evaluate Holocene vegetation responses. This study focuses on the extra-Andean sector, where new pollen records from La Tapera (LTap) and Cisne 7 provideinsights into steppe vegetation dynamics under dry conditions. These sequences are contrastedwith previously studied records further west (LF, ZB, CMN1, CMN2, and COCU)to assess west–east gradients in vegetation change and moisture availability throughoutthe Holocene. Western records indicate that the Early Holocene was dominated bygrass–dwarf-shrub steppe under arid conditions, followed by increased humidity around7600 cal yr BP that promoted the development of forest–steppe ecotonal environments. TheMiddle Holocene was characterised by aridity, reflected in shrub dominance and reducedforest signals, whereas the Late Holocene included a humid pulse between ~1750 and1000 cal yr BP, followed by renewed aridity over the last millennium. In contrast, easternrecords show persistent shrub–dwarf-shrub steppes since ~4700 cal yr BP, with vegetationchanges expressed mainly as shifts in the relative dominance of shrubs and dwarf–shrubsrather than floristic replacements. Archaeological sites corroborated and complemented thecontinuous records, strengthening the reconstruction of environmental variability acrossdifferent temporal windows. Overall, this west–east comparison highlights the differentialsensitivity of ecosystems to SWW fluctuations, reinforcing their role as an important forcingof hydrological balance and vegetation dynamics in mid-latitude Patagonia.