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

Abstract

This paper provides 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). Four major types of paleoclimatic 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.

Introduction

The complex paleoclimatic history of the late Paleozoic has captured the attention and imagination of geologists since the end of the XIX century when the existence of glacial deposits began to be reported from distant areas of Gondwana (Blanford et al., 1859, Sutherland, 1870, Keidel, 1916, Du Toit, 1921). The Gondwanic glaciation, which represents the longest duration glacial interval recorded during the Phanerozoic (Frakes et al., 1992), lead to the formation of glacial deposits in much of South America, South Africa, India, Antarctica and Australia and in several basins of the Perigondwanic region (López Gamundí et al., 1992, López Gamundí, 1997, Visser, 1997, Isbell et al., 2003a, Isbell et al., 2003b, Isbell et al., 2008b, Rocha-Campos et al., 2008). The effect of the glacial conditions was not limited to Gondwana, and in fact, glacial and interglacial periods affected sedimentation patterns also in the equatorial region (Veevers and Powell, 1987, Heckel, 1994, Isbell et al., 2003a, Shi and Chen, 2005, Montañez et al., 2007, Rygel et al., 2008).

Although this glacial mega-event took center stage for a long time, the late Paleozoic paleoclimatic evolution was much more complex. As mentioned by Gastaldo et al. (1996) and Isbell et al. (2008a), the late Paleozoic was a unique period in the Earth history in which a long-term transition from icehouse to extreme greenhouse conditions has been preserved on a global-scale. Therefore, the glaciation represents only the icehouse end member of the transition, while warmer postglacial climates followed by increasing drier conditions, and ultimately arid climates (the extreme greenhouse end member) completed the series.

Evidence for the shift from glacial to arid climates, or at least strong seasonality, during the middle and late Permian comes from several different sources including: paleoenvironmental (López Gamundí et al., 1992, Limarino et al., 1997, López Gamundí, 1997, Retallack, 2005, Isbell et al., 2008a, Isbell et al., 2008b, Gulbranson et al., 2010), paleontological (Gastaldo et al., 1996, Rees et al., 2002, Retallack et al., 2006), and stratigraphic studies (Kidder and Worsley, 2004, Limarino and Spalletti, 2006, Retallack et al., 2006, Holz et al., 2008). Moreover, recent researches on the oxygen and carbon isotopic records during the late Paleozoic also suggest a progressive transition from icehouse to extreme greenhouse conditions from the middle Carboniferous to the late Permian (Hyde et al., 2006, Montañez et al., 2007, Grossman et al., 2008).

Extreme greenhouse conditions, reached towards the end of the Permian, coincided with a massive extinction that devastated not only terrestrial but also marine ecosystems (Erwin et al., 2002, Clapham et al., 2009, Metcalfe and Isozaki, 2009). The latest Permian extinction at ≈ 252 Ma was the largest biotic catastrophe of the Phanerozoic, resulting in the disappearance of ≈ 90% of skelenotized marine species and ≈ 70% of terrestrial vertebrate species, bringing life close to annihilation (Algeo et al., 2011, Chen and Benton, 2012; and references provided therein). The most accepted explanation to this end-Permian biotic crisis includes huge volumes of CO₂ during the eruption of basaltic lava of the Siberian traps, which led to rapid global warming and the short-term production of acid rain devastating land ecosystems. Terrestrial–marine teleconnections contributed to the marine biotic collapse where increased CO₂ concentration, anoxia, euxinia (anoxic and sulfidic conditions), and hypercapnia (CO₂ poisoning), among other potential triggers, were recorded (Algeo et al., 2011, Chen and Benton, 2012). Nevertheless, sanctuary or sanctuaries located in the Gondwanan polar or subpolar regions life to survive the end-Permian mass extinction and contribute to the recovery and restoration of marine Triassic ecosystems (Waterhouse and Shi, 2010).

The aim of this review is to examine and evaluate the icehouse–extreme greenhouse paleoclimatic evolution of the late Paleozoic basins in southern South America in the light of recent stratigraphic information. For these purposes the paleoenvironmental, paleontological, paleogeographical and geochronological information available at present is discussed and placed in a conceptual model of paleoclimatic evolution for the late Mississippian to the end of the Permian.

For this study, we have restricted our observations to South American basins included in the classical late Paleozoic Gondwanic realm located to the South of the Guaporé Craton (presently, south to 12° south latitude, Fig. 1). Patagonia has been excluded due to its imprecise paleogeographic location as it is considered to be an allochthonous terrane (Ramos, 1984, Ramos, 2008) or a parautochthonous crustal block that collide with South America during the late Carboniferous–early Permian.