Late Quaternary glacial chronology on Nevado Illimani, Bolivia, and the implications for paleoclimatic reconstructions across the Andes

¹⁰Be terrestrial cosmogenic nuclide surface exposure ages from moraines on Nevado Illimani, Cordillera Real, Bolivia suggest that glaciers retreated from moraines during the periods 15.5-13.0 ka, 10.0-8.5 ka, and 3.5-2.0 ka. Late glacial moraines at Illimani are associated with an ELA depression of 400-600 m, which is consistent with other local reconstructions of late glacial ELAs in the Eastern Cordillera of the central Andes. A comparison of late glacial ELAs between the Eastern Cordillera and Western Cordillera indicates a marked change toward flattening of the east-to-west regional ELA gradient. This flattening is consistent with increased precipitation from the Pacific during the late glacial period.