Microbially induced sedimentary structures (MISS) allow re-assessing late Holocene lake level fluctuations in Lago Cardiel, Southern Patagonia (Argentina) – Geomorphological and archeological implications

Lake-level fluctuations in closed basins provide valuable insights into past climates across multiple temporal scales. Microbially induced sedimentary structures (MISS) contribute significantly to high-resolution paleoenvironmental reconstructions. Lago Cardiel, a key site for paleoenvironmental studies in Patagonia, has been extensively studied since the late 1980s. This study refines late Holocene lake-level fluctuations using a multiproxy approach, including stratigraphic, paleontological, and archaeological data within a robust chronological framework. For the first time, MISS have been identified as a result of recent lake-level drops. Four MISS levels (L1–L4) were documented in a northern bay near the archaeological site Patito Destapado, at elevations of 288–295 m a.s.l., interbedded with sand and gravel. Gastropods (Lymnaeidae and Chilinidae) from levels L1 and L3 were radiocarbon-dated to 2087 ± 21 and 3327 ± 26 years BP, respectively. L2 (289 m a.s.l.) corresponds to the PD site, dated to 3015 ± 31–3436 ± 35 years BP. These findings link archaeological site reoccupations with recurrent low lake levels during the Late Holocene. The presence of MISS marks extended low-water periods, which created more accessible landscapes for human activity and settlement.