Análisis sedimentológico de la formación La Invernada, pleistoceno tardío-holoceno, pedemonte de las Sierras de Comechingones: Provincia de Córdoba, Argentina

this work is aimed at analyzing the sedimentology and paleoenviroment of the late pleistoceneearly holocene deposits outcropping along several creeks which drain the eastern foothills of the southern sierra de comechingones. to investigate the vertical and spatial relationships between fluvial and aeolian deposits, 18 detailed vertical sections were logged and complemented with several architectural panels and discontinuity surface tracing along 30 km in a nnw-sse trend (fig. 1). the facies analysis was accompanied by mineralogical characterization of the sand-sized grain fraction (0.062 mm) and the fossil register. the climatic factors were considered to define the paleoenviromental model. the succession studied is part of la invernada fm (cantú, 1992), presents a maximum thickness of 15 m and overlie discordantly over older quaternary sediments assigned to either pampeano fm (frenguelli, 1955) or conchancharava fm (cantú, 1992). bones and isolated fossil pieces indicating lujanense mammal age were found within the studied sediments. these fossils belong to the pampeano and central domain, and most of them were interpreted to belong to browsers and grazers. the mineral constituents within the sand fraction are uniform in all deposits studied. however, in considering individual minerals, the observation of differences in the advance of weathering and morphometric properties suggest that at least two populations of minerals coexist within every sample. the light minerals, including quartz, alkali feldspar, plagioclase, and volcanogenic components (volcanic fragments) make up most of each sample (up to 98 %). whereas heavy minerals usually appear in low concentration, they show a wide spectrum given by combinations of pyroxenes, amphiboles, micas, lithoclast, garnet, apatite, turmaline, oxides, epidotes, and olivines. mineral constituents reveal the existence of three sources of clastic sediments: crystalline basement rocks (sierras pampeanas), acid volcanic rocks, an