Improved Constraints on Andean Glaciations From the Lake Titicaca Continental Drilling Record

Long sedimentary records from tropical lakes provide crucial archives for reconstructing the timing and extent of tropical alpine glaciations, yet robust chronologies beyond the radiocarbon limit (ca. 50 ka) remain scarce. Here, we refine the ca. 350 kyr chronology for Lake Titicaca (Peru-Bolivia) using radiocarbon dating, optically stimulated luminescence, and zircon combined U-Th and (U-Th)/He ages from volcanic ashes, enhanced by stratigraphic alignment to Lake Jun & iacute;n. New post-infrared infrared stimulated luminescence (pIRIR225) luminescence ages, constrained by sediment-specific water-content corrections, anchor a Bayesian age model extending reliably to similar to 350 ka. The new ages support the major features of the original chronologic framework for the Lake Titicaca drill core but shift ages in some older portions of the sequence. Alignment of magnetic susceptibility records between Titicaca and Jun & iacute;n sediments using dynamic time warping highlights clear regional coherence in Andean glacial maxima corresponding to Marine Isotope Stages 2, 6, and 8. These refined ages revise previous chronologies and underscore the sensitivity of tropical Andean glaciers to large-scale forcings associated with global climate cycles.