A Case for Replication: Climate of the Last Glacial Period Using Peruvian-Andes Speleothems

The South Asian Summer Monsoon (SASM) intensity fluctuates in accordance with temperature gradients from the Northern Hemisphere shifting from stadial to interstadial conditions, and these shifts are captured in speleothems (calcitic structures formed in karst caves, including stalagmites and stalactites) from the high-altitude Peruvian-Andes. These stalagmite records serve as an important indicator of Southern Hemisphere climate, given that most paleoclimate records have primarily been collected from the Northern Hemisphere, leaving the Southern Hemisphere relatively underinvestigated. This study explores a stalagmite from Antipayarguna Cave (11°16'S, 75°51'W) that is used to attempt to replicate the record of a stalagmite collected in Pacupahuain Cave (11°24'S, 75°82'W) from Kanner et al. (2014), one of the pioneers of Peruvian-Andes speleothem studies. These stalagmites were sampled for δ13C and δ18O stable isotopes and trace metal concentrations (Mg/Ca and Sr/Ca ratios). By coupling both stalagmite records, which span throughout the last glacial period (~15,000 - ~27,000 years BP), these proxies complete a comprehensive record of regional precipitation that influences speleothem formation, including Rayleigh Distillation and the Amount Effect. Higher δ18O values in stalagmites depict more intense rain, and lower δ18O depicts a drier climate and less rainfall, both influenced by the climatic dynamics of the SASM and the InterTropical Convergence Zone (ITCZ). The δ13C and trace metals are dependent upon more local influences, including vegetation type and geologic setting, and constrained to just δ13C, respiration and degassing. The replication of a previous study with this APG stalagmite serves to improve and confirm the results and interpretations of Kanner et al. (2012) and help distinguish local versus regional effects, as it was until now a non-replicated stalagmite study.