Paleoenvironmental Reconstruction of the Destacamento Río Salado Member, Canal de Las Escobas Formation (Middle Holocene), Northeastern Buenos Aires, Argentina: Sedimentological and Paleontological Evidence

The paleoenvironment of the type section of the Destacamento Rio Salado Member, (Canal de las Escobas Formation, Middle Holocene, northeastern Buenos Aires province, Argentina) is described from sedimentological and paleontological points of view. Two lithofacies association were recognized: muddy lithofacies association includes lenticular, planar lamination and homogeneous sedimentary structures, and represents subaqueous decantation of clay in intertidal-subtidal depositional environments; the heterolithic lithofacies association includes wavy, hummocky, flaser, and cross-lamination lithofacies, suggesting periodic increases of fine sand input in an environment with variable tidal energy. Paleontological content includes: Ophiomorpha nodosa, Thalassinoides suevicus and Maiakarichnus isp., dominate in ichnofauna along the stratigraphic column; Oblongichnus isp. is produced by the infaunal bivalve Solen tehuelchus, confirming a shallow littoral environment. Molluskan shell concentrations includes parautochthonous-allochthonous components in beds, lenses, pouches and pods and suggesting variation in water energy; borings in carbonate fragments and bioclasts indicates that they were exposed to the surface prior to final burial. A complete fur seal skeleton indicates that it was rapidly buried after death, indicating the presence of sedimentation rhythmicity. Micropaleontological evidence confirms the interpretation based on lithofacies analyses. The integrated analysis of the sedimentological and faunal composition suggest marine dominant provenance with minor fluvial components.