Microstratigraphy and palaeoenvironmental implications of a Late Quaternary high‐altitude lacustrine record in the subtropical Andes

High-mountain lake records in semiarid foreland settings, such as the central Andes of North-western Argentina, are highly restricted and often deprived well-preserved microstratigraphic information to analyze palaeoenvironmental changes their causes, particularly for periods prior Last Glacial Maximum. Laguna La Salada Grande (23°S/65°W, 4063 metres above sea-level) is a closed shallow located at Cordillera Oriental, Argentina with unique depositional record, including geomorphic stratigraphic evidence since Late Pleistocene. In order understand dynamics this mountain lacustrine system different timescales, limnogeological multiproxy analyses together radiocarbon 210Pb-based chronology were applied on massive laminated sediments from Grande. Laminated deposits further analyzed using novel sub-centimetric mineralogical, textural geochemical automated methods (including combination micro-X-ray fluorescence quantitative evaluation minerals by scanning electron microscopy (QEMSCAN®). Thick microfacies beginning sequence record deep organic matter productive palaeolake ca 34 ka (1 = 1000 years before 1950), that changed into fluctuating shallower-palaeolake frequent detrital influxes after ka. Microstratigraphy coarser-grained laminae between 31 25 reveals irregular probably sub-centennial high-energy discharge events, pointing convective atmospheric activity main trigger. After 21 evolved deeper water-level conditions resulting fine-grained limited delivery coarse-grained sediments, followed an abrupt level drop incision. The multi-millennial reconstruction Grande, its correlation other palaeoclimate records, shows close link processes associated South American summer monsoon dynamics. This multifocal research understudied environment provides key knowledge about functioning events−climate interactions lakes semi-arid climates.