A Neoproterozoic paleokarstic surface in the upper Villa Mónica Formation, Tandilia System, Argentina: Preliminary constraints on its origin and diagenesis

LUCÍA GÓMEZ PERAL, DANIEL POIRÉ, ALCIDES SIAL, JULIA ARROUY

San Pablo

Congreso; 6° Latin American Congress of Sedimentology; 2013

An uplift registered on top of the formation is related to period of intense erosion and weathering with generation of a karstic surface over the dolostones as a telodiagenetic surface. This important unconformity was situated, from palaeomagnetic studies, in 595 Ma and is characterized by dedolomitization, intense dissolution and precipitation if iron oxides, chert and calcite. Siliceous cementation and replacement was assumed for subaerial exposure, when pH dropped, and was associated to sea-level fall of uncertain relation with glaciation. This surface constitutes the contact between Villa Mónica and Colombo Formations, representing an extent period of erosion, and called as "Piedra Amarilla surface?.