Determination of an age model based on the analysis of the δ 18O cyclicity in a tropical glacier

Oxygen isotopes δ18O from a 13 m ice core derived from the Antisana volcano ice cap (0° 28′S, 78° 08′W), Ecuador, were analyzed to generate an age model based on isotopic fluctuations. The inferred age model spans c. 3.6 years, from 1993 to mid-1996, and corresponds to 3.6 cycles of isotopic fluctuations driven by seasonal change in precipitation in western Amazonia. A logarithmic transformation (LT) was performed on the ice core density data to remove the compression effect of accumulated snow affecting the temporal fluctuation of the isotopic signal. A wavelet analysis run on the decompressed isotope signal (LT) showed periodicities of 80, 40, and 20 corresponding to 12, 6, and 3 months, respectively. The results were compared against the isotopic record from the Chimborazo ice core data to validate its temporal match with a hydrological year. The LT isotopic signal showed a significant correlation with the Chimborazo isotopic data (r = 0.69 and p-value