Fig. 6: Average adjusted composition of fluids from low-temperature basalt alteration (Clt), calculated using Eq. 2.

a Ca2+ component of Clt based on a range of compositions for groundwater discharging from passive margins (Cs). The x axis (Groundwater composition) indicates the fraction of CaCl2 brines in two-component mixing between the clastic-derived and CaCl2 brine archetypes. b K+, Mg2+, and Na+ components of Clt for the conditions in a. c Ca2+ component of Clt for Qlt ranging from 0.5 to 2.0 × 1013 m3 yr−1 (ref. 11). d K+, Mg2+, and Na+ components of Clt for the conditions in c. Source data are provided as a Source Data file.