Paleocurrent Analysis of the Piedras de Afilar Formation (Neoproterozoic, Uruguay)

A detailed paleocurrent analysis was carried out in the outcrop area of the Piedras de Afilar Formation, which is a sedimentary succession corresponding to a shallow marine platform. With the aim of analyzing paleocurrents and their importance in basin analysis, a survey at the outcrop level was carried out. Paleocurrents measured in interference ripple marks suggest a NW-SE paleo-shoreline. Flute cast paleocurrents with directions towards NE and measured paleocurrents in Cuchilla Alta, in planar cross-stratification and trough cross-stratification (bimodal to oblique patterns to the NE and SE), suggest a provenance from the west. A rotation in the paleocurrent direction due to deformation was observed, which required a systematic correction. Considering this, a regional drag fold is interpreted as a sinistral shear sense indicator for the Sarandí del Yi Shear Zone reactivation. Regionally, the Arroyo del Soldado Group presents paleocurrent directions mainly to the east, similar to the Piedras de Afilar Formation. This suggests a provenance from the west for the mentioned Neoproterozoic units, which is confirmed by the detrital zircon ages, with Mesoproterozoic ages, interpreted as a provenance from a proto-Andean belt of the Río de la Plata Craton, counterpart of the Grenvillian in Laurentia.