1 The Origin of Continental Carbonates in Andean Salars: 2 A Multi-Tracer Geochemical Approach in Laguna Pastos Grandes (Bolivia) 3 E. Muller1, E. C. Gaucher2, C. Durlet3, J.S. Moquet1, M. Moreira1, V. Rouchon4, P. 4 Louvat1, G. Bardoux1, S. Noirez4, C. Bougeault3, E. Vennin3, E. Gérard1, M. Chavez5, A. 5 Virgone2, M. Ader1 6 1Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France 7 2Total CSTJF, Avenue Larribau, 64018 Pau Cedex, France 8 3Biogéosciences, UMR 6282 CNRS, 6 boulevard Gabriel, Université Bourgogne 9 Franche-Comté, 21000 Dijon, France 10 4IFP Energies Nouvelles, 1-4 Avenue de Bois Préau, 92852, Rueil-Malmaison Cedex, 11 France 12 5Total E&P, 40 Calle Las Violetas, Edificio Arcus, Santa Cruz de la Sierra, Bolivia 13 Corresponding author: Elodie Muller (
[email protected]) 14 15 This article has been accepted in Geochimica et Cosmochimica Acta. 16 Abstract 17 In continental volcanic settings, abundant carbonate precipitation can occur with 18 atypical facies compared to marine settings. The (bio-)chemical processes responsible for 19 their development and early diagenesis are typically complex and not fully understood. In 20 the Bolivian Altiplano, Laguna Pastos Grandes hosts a 40-km2 carbonate platform with a 21 great diversity of facies and provides an ideal natural laboratory to understand the processes 22 responsible for the precipitation of carbonates in a continental province dominated by 23 volcanism. In order to trace the origin of both water and solutes in the lagoon, the major 24 element and stable isotope compositions (δ2H-δ18O, δ37Cl, δ7Li, δ11B and 87Sr/86Sr) of the 25 spring and stream waters were characterized, as well as the stable isotope compositions 26 (δ13C, δ15N) and noble gas isotope ratios of hydrothermal gases associated with spring 27 waters.