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Fig. 4. Changes in mineral saturation indices (Q/K) at 200- and 400-m depths for selected minerals, for the change in surface infiltration flux scenario. Saturation indices for fracture waters are indicated by square symbols, and matrix water by round symbols. Open black symbols indicate the initial saturation indices, and the red filled symbols indicate the new steady-state saturation indices. The minerals represented in the figure are labeled along the horizontal axis. Values of Q/K <1.0 indicate solutions that are undersaturated with respect to the indicated minerals, and which would dissolve the mineral if present, while values >1.0 indicate supersaturated waters from which the indicated minerals would precipitate. Illite, mordenite, and smectite are strongly supersaturated (Q/K 
>2.0) in matrix and fractures at 200 m, but exhibit more complex relationships at 400 m. Note that Q/K for illite and smectite initially exceeds 2.0 in the matrix at 400 m. Q/K for kaolinite is consistently >>1.0 under all conditions.
