Lacustrine Facies in the Upper Cretaceous Balbuena Subgroup (Salta Group): Andina Basin, Argentina

• Autores: R. M. Palma
• Localización: Lake basins through space and time / coord. por Elizabeth H. Gierlowski-Kordesch, K. Kelts, 2000, ISBN 0891810528, págs. 323-328
• Idioma: inglés
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• Resumen

  • The Cretaceous-Early Tertiary Andina Basin in northwestern Argentina was formed during an initial phase of rifting (syn-rift), followed by a long period of thermal subsidence (post-rift). The basin contains at hick continental succession (7500 m) that comprises siliciclastic and carbonate rocks (Table 1). The Cretaceous-lower Tertiary sequence belongs to the Salta Group (Figure 1), which is exposed in vast areas of the Salta and Jujuy provinces, with different recognizable depocenters (Lencinas and Salfity, 1973). The Salta Group is divided into three subgroups (Pirgua, Balbuena, and Santa Barbara; Table 1), which represent different stages in the evolution of the basin (Moreno,1970; Gomez Omil et al., 1989).

    The Pirgua subgroup consists of reddish gray conglomerates ,sandstones, and clay stones, interpreted as alluvial fan and fluvial deposits, which are associated in various outcropping zones with alkaline basalt(Galliski and Viramonte, 1988). The Balbuena subgrouplies conformably above these rocks and contains the Lecho, Yacoraite, and Olmedo Formations. Lithologically, these formations consist of extensive beds of sandstones, interpreted as fluvial and eolian depositswith a mixed carbonate/siliciclastic sequence of aprobable playa-lake complex. Units of the Santa Barbarasubgroup lie conformably above the Balbuenasub group and contain a monotonous succession of sandstones, clay stones, and limestones interpretedas fluvial and lacustrine in origin. The Santa Barbarasub group is assigned to the Paleocene-lower Eocene based on the presence of mammalian fossils (Pascual,1984)