Ostracods from upper Yacoraite Formation (Danian), Salta Basin, Western Argentina: Taxonomy and paleoenvironmental indicators of climatic signals in lacustrine deposits.

This paper presents the first study of nonmarine ostracods recovered from the Danian of the upper Yacoraite Formation (Balbuena IV sequence) Salta Basin. Six species were identified: Ilyocypris triebeli , Ilyocypris argentiniensis , Neuquenocypris (Alleniella)? sp. 1; Neuquenocypris (Alleniella)? sp. 2; Penthesilenula sp. and four indeterminate species. The ostracod fauna shows fluctuations in abundance, diversity, and preservation associated with different phases of the paleolake evolution. This distribution, clearly delineated by the depositional facies, corroborates previous geochemical analyses and high-resolution sequence stratigraphy developed for the section. In general, the most abundant occurrences of ostracods coincide with high-frequency transgressive tracts of the lake system, which form long-term wettest interval of the upper Yacoraite Formation. • First study with ostracods for the Balbuena IV sequence of the Yacoraite Formation, Salta Basin, Argentina. • Six nonmarine ostracods species are identified. • Temporal distribution of ostracods is in agreement with U/Pb radiometric dating. • Ostracod abundance is correlated with the climatic fluctuations of the dry and wet periods of the paleolake. [ABSTRACT FROM AUTHOR]