Paleotropical Climate and Vegetation Linkages to Southern Gondwanan Glaciation: Extending the Early Permian Record into the Late Mississippian

The longest-lived icehouse of the past half billion years, the Late Paleozoic Ice Age (LPIA) came to a close in the Early Permian, transitioning into an ice-free warm period that was sustained arguably until the onset of our current glacial state ~34 million years ago. For the final stage of the LPIA, integration of newly developed paleo-high-latitude glacigenic and paleotropical marine and terrestrial records document covariance between repeated shifts in inferred paleoprecipitation, pCO₂, paleotropical SSTs, and extent of Gondwanan glaciation consistent with CO₂-forcing of climate. Here we present new results from several basins across paleotropical Euramerica (Appalachian Basin, USA; Donets Basin, Ukraine; Paganzo Basin, northwest Argentina) that extend the apparent CO₂-climate-glaciation link down into the Carboniferous. Integration of soil carbonate δ¹³C and δ¹⁸O, fossil plant matter δ¹³C and δ¹⁵N, paleosol morphologies, and lithologic trends from late Mississippian through Pennsylvanian paralic to fully terrestrial successions delineates discrete intervals (2 to 4 Myr) of decreased effective moisture and increased seasonality likely associated with elevated atmospheric pCO₂. Drier intervals are intercalated with those characterized by humid climate paleosol morphologies and lithologies, significantly lower pedogenic and meteoric calcite δ¹⁸O values, and estimated present-day pCO₂. Two inferred ‘drier' intervals (late Mississippian and latest Moscovian through Kasimovian) – possibly greenhouse gas-forced - coincide with periods of normal marine and fluvio-deltaic sedimentation, or long-lived pedogenesis in high-latitude southern Gondwana, indicating drier periods coincided with periods of glacial minima or possibly ice-free conditions. Integration of our proxy records with tropical paleobotanical records reveals repeated major restructuring of flora in-step with climate and pCO₂ shifts. Notably, major floral shifts documented across the middle-late Pennsylvanian boundary and Permo-Carboniferous transition are coincident with mineral isotopic and sedimentologic evidence for increased aridity and seasonality; abrupt shifts in fossil plant isotope values record the impact of these climate transitions on tropical flora.