Quaternary continental deposits in the northeast Buenos Aires province

Abstract

Geological and paleontological features of the continental units cropping out at this area of the Pampean region are described. These features suggest that the continental (fluvial, eolian and weathering) processes have had a major influence in the development of the different geoforms, lithological units, and fossil components. The continental deposits mostly developed and widely distributed in the area are those composed of loess and loessoid silts grouped as the Pampeano Formation. This mainly eolian unit, has been reworked in some cases by water and gravitational processes, and affected by weathering, and also involves fluvial and lacustrine facies. Because of its homogeneity, its differentiation has been often based on non-lithological aspects, being arbitrary, and making difficult the correlation with other exposures, especially regarding its horizontal discontinuity, and when little thickness is exposed. Consequently, it is considered that the name of Pampeano Formation for all these sediments is more appropriate to reflect the characteristics of the unit. Other units cropping out in the area are also described, such as the La Postrera Formation, the channelled deposits of the Luján Formation and the modern alluvium, the geosols Puesto Callejón Viejo and La Pelada, and the mixed or littoral units of the Pilar and Campana formations.