Sedimentary aspects and paleoenvironmental evolution of a rift basin: Salta Group (Cretaceous-Paleogene), northwestern Argentina

R, M.; CECILIA EUGENIA DEL PAPA; I, S.

International Journal of Earth Sciences

Springer-Verlag

Año: 2005 vol. 94 p. 94 - 113

1437-3254

The Salta rift history was related with the evolution of the Central Andes and, due to its geographic location, with the activity of the Pacific margin. Sedimentation occurred from Neocomian to Paleogene, the deposits reach a thickness of 5,000 meters. The paleoenvironmental analysis reveals an evolutionary history controlled by tectonic and climatic changes. Isolated grabens characterized the synrift stage, differential subsidence provoked distinct environments of the southern and northern subbasins. In the southern area, alluvial-fan, fluvial-fan and lacustrine deposits prevailed, and in the northern area eolian and fluvial environments dominated. During the Maastrichtian, two major factors controlled the basin fill: the decrease in tectonic subsidence and the South American sea level rise. An extensive and shallow Atlantic marine ingression installed a carbonate system coincident with mainly humid conditions until the Danian. Until the Middle Eocene, the fluvial and lacustrine environmental evolution of the sag basin was specially controlled by the alternation of temperate with dry and humid periods. The paleontological records reflect these climatic changes and show their relationship to the sedimentation regime. Diversity, characteristics and preservation are in agreement with the interpreted environments.