Fig. 3: Potassium isotope fractionation during dissolution and aluminosilicate neoformation.

δ⁴¹K_rw versus K/Na* ratios, where Na* = [Na⁺] – [Cl⁻]. The curves indicate modeled silicate dissolution (batch or Rayleigh fractionation) followed by aluminosilicate neoformation (Rayleigh fractionation), with potential fractionation factors based on Li et al. (2021)³³. The loess K/Na* ratio is calculated from Sauzeat et al. (2015) and Huang et al. (2020)^11,36. The labeled bars show the proportion of remaining K⁺ relative to the conservative Na⁺. The pink and brown shadings show the feasible zones from Rayleigh and batch dissolution, respectively.