They wrote that groundwater fluctuations appear to be the major factor controlling ELD deposition. They noted that the ELDs inside the craters would likely have originated by fluid up-welling through the fissure ridges and the mounds, and that lead to evaporite precipitation. The presence of spring and playa deposits points to the possible presence of a hydrological cycle, driving groundwater upwelling on Mars at surface temperatures above freezing, according to lead researcher Monica Pondrelli from Italy-based International Research School of Planetary Science.
Pondrelli and colleagues wrote that such conditions in a similar Earth environment would have been conducive for microbial colonization.
As a basis for their research, Pondrelli and colleagues produced a detailed geological map of the Firsoff crater area.
The new map includes crater count dating, a survey of the stratigraphic relations, and analysis of the depositional geometries and compositional constraints. They noted that this ELD unit consists of sulphates and shows other characteristics typical of evaporites such as polygonal pattern and indications of dissolution.