Palaeoecology and sedimentology of Carboniferous glacial and post-glacial successions in the Paganzo and Río Blanco basins of northwestern Argentina

Abstract

AbstractRecent studies show that Late Palaeozoic Ice Age (LPIA) climate change broadly affected marine invertebrate faunas: glaciations decreased origination and extinction and long-term gradual global warming during the final deglaciation altered palaeocommunity composition. Carboniferous stratigraphy and palaeoecology in the Paganzo and Río Blanco basins of southwestern Gondwana (present-day Argentina) were studied in ordered to further determine how palaeocommunities were influenced by glacial and post-glacial processes during the LPIA. In the Paganzo Basin, the Guandacol Formation consisted of an ice-proximal to very ice-distal glaciomarine succession, while the Tupe Formation represented continental fluvial lowstand sedimentation interrupted by periodic marine incursions (estuary setting). In the Río Blanco Basin, the Río del Peñon Formation represents a shallowing-upwards coastal marine facies under the influence of wave and storm activity. Diversity and abundance data from northwestern Argentina reflects that ice-proximal environments proved physiologically stressful to organisms, limiting colonization to only opportunistic fauna. Following glaciation, the fauna of northwestern Argentina diversified and became increasingly ecologically complex during two marine transgressions in the Río Blanco Basin. It is interpreted that palaeocommunity establishment, composition and diversification in western Argentina during the LPIA was mostly dependent upon localized environmental conditions and palaeogeographic location.