Extended Data Fig. 2: Age Model for stalactite 13RM620-B (depicted with both U/Th and stable isotope subsample transects).

a, As in Extended Data Fig. 1a, except the youngest calcite subsampled for δ¹⁸O_c begins 40.25 mm from the tip; a hiatus immediately above this depth results in an abrupt transition into higher-²³²Th calcite (not shown). Dates plotted in blue were excluded from age model construction due to high ²³²Th concentrations, indicating relatively abundant non-radiogenic thorium and requiring larger age corrections with uncertain initial ²³⁰Th/²³²Th values. b,c, As in Extended Data Fig. 1b and c. The consistent, part per billion concentrations of included ages can be contrasted with the variable, higher-²³²Th character of excluded ages irrespective of depth.