Concepts of way-up are really only applicable to a single evaporite cycle in a closed system. More usually, evaporite systems are semi-open dynamic systems and the phases deposited reflect that dynamism.

When recharge is lowest, more extreme salts are deposited and when recharge is less low, less extreme ones. Recharge must always be limited, or the salts get flushed out.

And, what would the composition of a martian brine be, anyway? Seawater on Earth is a result of 4.5 Ga of aqueous processing of the crust, and a lot of mantle convection, crustal recycling, and atmospheric interaction.

Salts on Mars might start from a rather different perspective...

(nonetheless, thanks for re-posting that diagram, it makes a useful start)