Secondary minerals from salt caves in the Atacama Desert (Chile): a hyperarid and hypersaline environment with potential analogies to the Martian subs.

Over the past 15 years several expeditions by French, American and especially Italian cavershave unveiled over 50 caves in the Cordillera de la Sal (Atacama Desert, Northern Chile).Many of these caves contain a variety of speleothems and minerals, some of which haverarely been observed within karst systems. Most of the secondary deposits in these caves arecomposed of halite, but also other halide, carbonate, sulphate, nitrate, phosphate, and silicateminerals have been found. Among the sixteen cave mineral species recognized, atacamite,darapskite, blödite, leonite, anhydrite, and especially antarcticite are worth mentioning. In oneof the samples an unknown Ca-Sr-bearing chloride mineral has also been discovered, but ithas not been possible to carry out detailed mineralogical analyses. These often-rare mineralshave formed in this region due to the very extreme hyperarid and salt-rich environment. Thisresearch reports the mineralogical results and proposes the genetical mechanisms leading tothe formation of antarcticite, powdery anhydrite, and the paragenesis of the halite-darapskiteblödite.This study also shows that Atacama caves may be excellent analogues to studyweathering processes and subsurface secondary minerals in hyperarid and hypersalineenvironments on Mars.