Análisis paleoambiental de la formación mata amarilla a partir de su malacofauna, Cuenca Austral, Patagonia, Argentina

Abstract

Paleoenvironmental analysis from Mata Amarilla Fm malacofauna, Austral Basin, Patagonia Argentina. We present here a paleoenvironmental model for the Lower Upper Cretacic Mata Amarilla Fm lower section, in the Austral Basin. This work is made from detailed sedimentologic logs, facies analysis and the study of its paleontological and taphonomical associations. The unit is composed of alternating white sands and mudstones, with bioclastic accumulations intercalated in the lower section. The depositional environment for the Mata Amarilla Fm is a lagoon limited by shallow marine bars. The fine sedimentation is sporadically interrupted by storm events represented by coquines, bioclastic sands and valve pavements with an heterogeneous and allochtonous malacofauna association. Some areas of the lagoon become exposed allowing the development of vegetation on the susbstrate and the generation of pedogenetic processes. Lately, an advanced regression stage occurs when a fluvial system invades the lagoon area representing the begginig of the Mata Amarilla Fm Upper Section deposition.