Evaporite Environments on Earth as a Potential Mars Analogue

Sulfates have been identified on Mars and in particular jarosite and gypsum. It has been proposed that the sulfates were deposited as evaporites in enclosed standing bodies of water. Gypsum is deposited in both Permian and modern Australian acidic evaporite environments. Gypsum is also found in Storrs Lake, an alkaline evaporite and minimal amounts are associated with the Dead Sea salts which is mildly acidic lake. Gypsum can be associated with calcium carbonate, but it is dependent on the ions in solution and particularly HCO3.

We will compare several different evaporite basins and discuss the relation of calcium sulfate, specifically gypsum, and its integral relation with salts. All evaporite bodies on Earth contain microbes even though their mineralized form is not always evident. Microbes have also been identified in halite water inclusions and in some cases the microbes appear to have been present for millions of years.

The existence of water on Mars would be critical for the support of microbes. The NASA Phoenix mission is presently investigating the existence of water in the form of ice at the martian north pole.