CALIZAS ESTROMATOLÍTICAS Y OOLÍTICAS Y DEFINICIÓN DE LA FORMACIÓN ARROYO DE LA PEDRERA VENDIANO URUGUAY

Abstract (English)

The Arroyo de la Pedrera Formation is defined as a new Vendian lithostratigraphic unit of Uruguay. The depositional systems are raade up of: (a) a shallow siliciclastic shelf formed by orthoquarzites and mudstones, grouped in the Cerros San Francisco Member; and (b) peritidal carbonates, which define the Cerro Victoria Member, whose depositional systems extends from the shallow subtidal to the supratidal. They are recognized by oolites, stromatolitic associations and scarce trace fossils. An intermitent subaerial exposition is recognized by tepee-structures, balite pseudomorphs and other features. The sediments are arranged in a shallowing - upward sequence, interrupted by tempestites, developed on a stable shelf, located on the margin of the Rio de la Plata Craton. The age of the formation is inferred by stratigraphic relationships and trace fossils. Deposition took place in a warm water environment, implying low paleolatitudes.