"Hairy blobs:" microbial suspects preserved in modern and ancient extremely acid lake evaporites

"Hairy blobs" are unusual clumps of organic bodies and sulfate crystals that have been found in evaporite minerals grown in acid saline lakes. Here, we document modern hairy blobs in halite and gypsum from 5 modern acid saline lakes in southern Western Australia, and Permian hairy blobs trapped in halite from the mid-Permian Opeche Shale in the subsurface of North Dakota. These are among the first microbial remains described from acid saline lake environments. They give clues about the role of microorganisms in the acidity, geochemistry, and mineralogy of these extreme environments. This study also may add to the inventory of life in extreme environments and help predict possible martian life-forms and the method of preservation.     

Modern and ancient extremely acid saline deposits: terrestrial analogs for martian environments?

Extremely acid (pH <1) saline lakes and groundwaters existed in the mid-Permian of the mid-continent of North America. Modern counterparts have been found in acid saline lake systems throughout southern Australia. We compare and contrast the Permian Opeche Shale of North Dakota and Nippewalla Group of Kansas to modern Australian salt lakes in southern Western Australia and in northwest Victoria. With the exception of some minor variations in pH, evaporite mineralogy, and water geochemistry, the Permian and modern systems are similar and characterized by: (1) ephemeral saline continental playas hosted by red siliciclastic sediments, (2) evaporite minerals, including abundant sulfates, (3) Al-Fe-Si-rich waters with low pH values, (4) acidophilic microbes, and (5) paucity of carbonates. The composition of these terrestrial systems is strikingly similar to compositional data returned from the martian surface. Specifically, both Earth and martian systems have high amounts of iron oxides and sulfates, and little, if any, carbonates. We propose that the modern and ancient terrestrial acid saline environments may be good analogs for possible environments on Mars.