Paleoenviromental evolution of the Cenozoic foreland basin to intermontane basins in the Eastern Cordillera, North-Western Argentina

Abstract

The stratigraphic and sedimentological characteristics of the Cenozoic deposits are very important aspects to investigate the tecto-sedimentary evolution of the Andean foreland basin to intermontane hinterland basins in north-western Argentina. These deposits lie in an unconformity or paraconformity relationship over the Salta Group (Cretaceous-Paleocene) or older deposits. During the middle Eocene-Pleistocene, the changes in the sedimentary paleoenvironment and its evolution are the direct result of tectonic effects, a change in base level and accommodation space. This study provides the results of the integrated analysis of the middle-upper Eocene to Plio-Pleistocene basins in the Eastern Cordillera, in north-western Argentina. These basins that have been generated in the Central Andes region in north-western Argentina during the Cenozoic tectonic convergence, we divided in four sequences in the evolution from middle to upper Eocene to Plio-Pleistocene. They present fluvial deposits of different topographic slopes, with development of ephemeral fluvial systems associated with dune fields, meandering fluvial systems in arid climates, interlaced sandy-gravelly fluvial systems, sinuous sandygravelly fluvial systems of intermediate to high sinuosity, with the development of lagoons and swamps of tropical climate during ~10 to ~5 Ma, and the change to arid - semiarid claimed condition from ~5 to ~2.5 Ma. The sedimentary record of the Plio-Pleistocene hinterland basin in the Eastern Cordillera and the adjacent Andean Puna Plateau in the Central Andes of NW Argentina constitutes geological archive that provide spatiotemporal insights into geological evolution and associated surface uplift. These basins, probably connected at their onset during the middle Eocene, are characterized by different subsidence histories, differences in sedimentary paleoenvironment evolution, variations in topographic slopes, changes in provenance and paleocurrents, resulting in differences in tecto-sedimentary history.