A paleoclimatic review of southern South America during the late Paleozoic: a record from icehouse to extreme greenhouse conditions

Abstract

This paper proposes a review of the Late Mississippian to Permian paleoclimatic history for southern South America based on lithologic indicators, biostratigraphic information, and chronostratigraphic data. The region is divided into three major types of basins: 1. Eastern intraplate basins (e.g., Paraná Basin), 2.Western retroarc basins (e.g., Paganzo Basin) and 3.Western arc-related basins (e.g., Río Blanco Basin). Fourmajor types of paleo-climatic stages are recognized in these basins: 1. glacial (late Visean-early Bashkirian), 2. terminal glacial (Bashkirian-earliest Cisuralian) 3. postglacial (Cisuralian-early Guadalupian), and 4. semiarid-arid (late Guadalupian-Lopingian). The glacial stage began in the late Visean and continued until the latest Serpukhovian or early Bashkirian in almost all of the basins in southern South America. During the Bashkirian-earliest Cisuralian (terminal glacial stage), glacial deposits disappeared almost completely in the western retroarc basins (e.g., Paganzo Basin) but glaciation persisted in the eastern basins (e.g., Paraná and Sauce Grande Basins). A gradual climatic amelioration (postglacial stage) began to occur during the earliest Permian when glacial deposits completely disappeared across all of South America. During this interval, glacial diamictites were replaced by thick coal beds in the Paraná Basin while north-south climatic belts began to be delineated in the western basins, which were likely controlled by the distribution of mountain belts along the Panthalassan Margin of South America. Towards the late Permian, climatic belts became less evident and semiarid or arid conditions dominated in the southern South America basins. Eolian dunes, playa lake deposits, and mixed eolian-fluvial sequences occur in the Paraná Basin and in the western retroarc basins. Volcanism and volcaniclastic sedimentation dominated along the western margin of South America at that time. The stratigraphic record obtained in southern South America supports a long duration transition from icehouse to extreme greenhouse conditions.