Middle Permian Telodiagenetic Processes in Neoproterozoic Sequences, Tandilia System, Argentina

Abstract

In the Tandilia Basin, Buenos Aires Province, Argentina, we study the genesis of mud beds and pipes in the Loma Negra Formation (Iimestones), Sierras Bayas area, together with the emplacement of alunite and aluminum phosphate sulfate (APS) minerals in the Las Aguilas Formatioo, Barker area.All these features are related to basin ioversioo, uplift, erosion, and injection or expulsion, or infiltration of fluids and oxidation reactions in the exhumed rocks during a telodiagenetic stage.On the basis of K-Ar dating of alunite in tbe Las Aguilas Formation (claystones) givíng an age of 254 ± 7 Ma (middle Permiau), these processes are considered to be linked to a major geological event which affected these Neoproterozoic Iithostratigraphic units: the folding of the Ventania System, located 150 km to the SW of the study area.