Facies stacking and lateral variability of travertines from the Quaternary Vega Botijuela, Salar de Antofalla Basin, Argentina

ABSTRACT Travertines are non‐marine sedimentary rocks, which are typically hydrothermal in origin and characterized by high depositional rates. Despite great advances in the understanding of the geomorphological, petrological and geochemical aspects of travertines, the recognition of these rocks in the geological record is not an easy task due to the multiple parameters involved in their formation, the variable potential of preservation and the lack of a facies model with application to the geological record. This study applies classic sedimentological and stratigraphic methods, looking for vertical and lateral facies distribution at the Vega Botijuela, Salar de Antofalla, Argentina. Travertines are geomorphologically compartmentalized into proximal, intermediate and distal zones, with spring waters in the proximal zone and mixed carbonate–siliciclastic sedimentation observed towards the distal zone. The presented data corroborate previous assumptions that these systems are dominantly progradational to aggradational. Vertical facies stacking is typically coarsening‐upward, with a dominance of carbonate mudstone interbedded with grainstone, rudstone and boundstone. Distinct facies associations are observed in the Vega Botijuela and are defined here as dome, fissure ridge, gently and steeply inclined slopes, stepped slope and terminal, according to morphological criteria applied elsewhere. Biotic and abiotic travertine precipitation occurs along the geomorphological zones and is related directly to different slope gradients. Throughout the depositional history of travertines, the carbonate facies occur interbedded with siliciclastic deposits from the Salar de Antofalla, generating local facies heterogeneity in the marginal areas of the basin. This is one of the first attempts to establish vertical stacking patterns to characterize facies associations, adding important insights towards the building of a travertine facies model. In this context, these findings can be applied to recognize travertines of the geological record developed in extensional sedimentary basin margins under arid climatic conditions.