Fig. 3: Drip water trace element concentrations compared to PCarbP evolution lines.

a Ca vs Mg, b Ca vs Ba, c Ca vs Sr, d Ca vs U, all error bars are 1 RSD. Blue datapoints are affected by PCP, green data points are affected PAP. The continuous and dashed lines correspond to the evolution of the drip water composition as a consequence of PCP and PAP. The 2 standard errors of the slopes of the trendlines in e (Sr vs Ca) and f (U vs Ca) are 0.032 and 0.28. We use calcite D_Mg, and D_Sr from ref. ⁶, taking into account the effect of high calcite Mg/Ca ratios on calcite D_Sr, and temperature on calcite D_Mg. Calcite D_Ba and D_U are from ref. ²². The aragonite D_Sr and D_U values are from this study, 1.31 and 1.76, respectively. Since there is a switch from PCP to PAP in the epikarst/aquifer or at the cave ceiling and initial concentrations may not be constant, we select the drip water element composition of the sample with the highest Ca concentration for the group with Ca < 0.65 mmol/L as a starting point for the PAP model. The approach used to model the evolution of the drip water composition is described in the methods section. In b the red dashed ellipse indicates drip water samples affected by PAP with SI_Ar > 0.38. The data can be found in Tables S2 and S3.