Figure 8.

Clay Compositions on Mg-Al-Fe_tot. The starting compositions are the Portage, Cumberland, and John_Klein amorphous compositions [Vaniman et al., ²⁰¹⁴; Morris et al., ²⁰¹⁴[ and the analogue comparison clays. Saponite and saponitic gel and serpentine from the nakhlites [Hicks et al., ²⁰¹⁴[ and griffithite [Treiman et al., 2014[ are also plotted. For the run compositions, we have plotted a range of mixtures of amorphous, olivine, plagioclase, and whole rock, reacted with GPW fluid at W/R of 1000 (purple color), 100 (green color), and 10 (brown color). The Portage whole rock reacted with CO₂-bearing GPW is also plotted, and the results of clays from runs of Portage whole rock reacted with GPW at Fe³⁺/Fe_tot from 10 to 75% (Figure 4). The Portage 70% amorphous, 20% olivine, and 10% whole rock reactions at W/R 1000 and 100 have compositions close to the saponite from the nakhlites. The Portage 70% olivine, 15% augite, and 15% plagioclase run at W/R 1000 and 100 are closer to Mg-rich serpentine, and this type of olivine-rich run may be analogous to the formation of Mg-rich ridges at Yellowknife Bay. W/R is the ratio of incoming fluid with reacted rock.