Carbonate U-Pb dating potential for chronostratigraphy – Insights from the Maastrichtian-Danian lacustrine Yacoraite Fm. (Salta Rift)

U-Pb LA-ICPMS geochronology of depositional carbonates demonstrated to be a potential chronostratigraphic tool for poorly time-framed sedimentary successions. However, not all carbonates are dateable. Evaluating the dating potential requires establishing the age accuracy and precision of various sedimentary and early diagenetic carbonates precipitated from the same system. This is of prime importance to boost future chronostratigraphic studies based on U-Pb LA-ICPMS analyses. The lacustrine Yacoraite Fm. (Maastrichtian-Danian, Salta rift, Argentina) was chosen to assess the dating potential of different co-precipitated carbonates, whose age was constrained by zircon U-Pb dating of interbedded ash layers. Results of analyses on 101 carbonate phases, including ooids microbialites and early cements, are presented. Criteria to discriminate preserved U-Pb depositional ages were proposed to construct a robust depositional age model. Statistical analysis of the preserved depositional ages and their relative uncertainties (2σ_ex) point towards two factors that have partially controlled the carbonate U-Pb dating potential: the mineralogy and carbonate type that in turn reflect the dominant precipitation processes (chemical, induced or mediated by microbial activity), and textures (grain/crystal size and primary pore network). The highest dating potential is displayed by the early calcite cements precipitated via chemical processes and composed of coarse crystals with no micropores. Conversely, ooids and microbialites, especially those composed of dolomite, have lower dating potential. Results from this study provide insights regarding the sequestration of U and Pb in lacustrine carbonates and encourage to preferentially target early diagenetic calcite cements to apply U-Pb LA-ICPMS geochronology for chronostratigraphic studies.