Puquios of the Llamara salt flat 

The Llamara salt flat is made up of salt crusts and smaller amounts of fine sediment. Among the most common salts are sulfates (gypsum, anhydrite), carbonates, nitrates and halides (common salt) that form a superficial crust (Vásquez et al., 2018), associated with deep groundwater, from the Pampa del Tamarugal aquifer. In the Puquios, the chemical analysis of these waters shows that there is a predominance of sulfates and dissolved sodium in them, although in some sectors chlorine or bicarbonate, and magnesium or calcium also predominate, especially towards the southwest of the salt flat (López et al., 2017). Geological and climatic conditions have allowed the development of microbial mats of cyanobacteria and other organisms and of microbial structures like evaporitic domes (stromatolites). Microbial mats are laminated structures, which are controlled by environmental factors such as light, temperature, salinity, dissolved oxygen, and the presence of sulfides. These laminations have different colorations as a result of the development of photosynthetic bacteria that contain photosynthetic pigments and, therefore, different patterns of available light (Farías et al., 2017). The evaporitic domes occur where microorganisms form aggregates occupying the pore spaces inside halite, where microbial interactions occur (Farías et al., 2017).