The Playa Hermosa Formation, Playa Verde Basin, Uruguay.

PAZOS, PABLO; RAPALINI, AUGUSTO E.; SANCHEZ BETTUCCI, LEDA; TOFALO, OFELIA R.

Geological society Memoir No.36 "The Geological Record of Neoproterozoic Glaciations"

The Geological Society

Lugar: Bath; Año: 2011; p. 547 - 554

Abstract The Playa Hermosa Formation is a volcano-sedimentary unit outcropping in the extreme south of the Dom Feliciano Belt in Uruguay. This unit was traditionally interpreted as not influenced by glacial processes until the interpretation of a glacial-related origin for the deposits in the lower part of the unit was suggested.  The stratigraphic position of the unit is subject of debate as well as its correlation with other Neoproterozoic units of Uruguay, Argentina and southern Brasil. Coeval sedimentation and volcanism provided the best constraints for its age suggesting circa 580 Ma for the contemporaneous magmatism using 39Ar/40Ar in hornblende, which is the best estimate for its sedimentation age. Preliminary paleomagnetic data from these sediments suggest a primary remanence for this unit and provide a mean geomagnetic pole consistent with the proposed apparent polar wander path for the Rio de la Plata craton. Although in need of confirmation, these data suggest that deposition of these glacigenic sediments may have occurred at low to intermediate latitudes. Future  research needs to be focused on absolute dating, reliable paleomagnetics and on a more accurate  interpretation of the geology and sedimentology of this and other Neoproterozoic units of the Rio de la Plata craton that are suitable for chemostratigraphy techniques and biostratigraphic approaches (e.g Arroyo del Soldado Group)