Abstract

SANCHEZ, María Cristina  and  MARQUILLAS, Rosa A.. Facies and environments of the Salta Group (Cretaceous-Paleogene) in Tumbaya, Quebrada de Humahuaca, JujuyProvince. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.3, pp.383-391. ISSN 0004-4822.

The red deposits of Salta Group (Cretaceous-Paleogene) which outcrops in the quebrada de Tumbaya, right margin of Quebrada de Humahuaca (province of Jujuy), they are characterized by facies that differs from the typical ones in their places of the Salta Group basin. They are proximal facies, characterized by arid and semi-arid conditions whose accumulation advanced on the N-NW side of the Salto-Jujuy high structure. Salta Group is separated from the underlying Cambrian Meson Group by an erosive discordance. An angular discordance at the top of the Group separates it from the superposed Quaternary deposits. In Tumbaya, the two main units of Salta Group, the synrift and post-rift, are represented. The research and study of sedimentary facies allowed to identify and to characterize the three Subgroups (Pirgua, Balbuena and Santa Bárbara) and to differentiate their formations. The Pirgua Subgroup consists of eolian sandstones; it is not possible to differentiate its three formation units, therefore it is mentioned as Pirgua Formation. The Balbuena Subgroup is subdivided into two formations, Lecho and Yacoraite Formations. The Lecho Formation is characterized by sheet floods facies and the Yacoraite Formation displays transitional, continental and marine litoral-sublitoral carbonatic environmental conditions influenced by tidal currents and storms. The three formations of Santa Barbara Subgroup are present: (Mealla, Maíz Gordo and Lumbrera), which represent a fining-upward fluvial succession with development of multiple paleosoils; there have also been identified sheet floods and floodplain facies.

Keywords : Tumbaya; Salta Group; Cretaceous-Paleogene; Facies; Paleoenvironments.

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