Notice on the major ridges that one side is green while the other is not.
This spot is a little south of the equator, and north is to the right, so it's the side that is more shaded from the sun that is green, as if the heat of the sun makes the water evaporate faster so the cooler side is better.
That happens a lot on earth too!
Seems to me that would make a biological explanation more plausible - if it was just mineral deposits from the water evaporating, there would be less of a difference than if it's due to algae that need the water in liquid form in the soil for a while instead of evaporating quickly.