PUTTING THE PALEO- IN PALEOCLIMATES: CONSTRAINING THE ROLE OF DIAGENESIS IN TERRESTRIAL PERMO-CARBONIFEROUS PALEOCLIMATE RECONSTRUCTIONS

Geologists live by the tenant that “the present is the key to the past” and much has been made about the past being the key to understanding the future of global warming. One time period that has been carefully studied as partially analogous to modern climate change is the Permo-Carboniferous. In particular, recent work reconstructing paleoclimate from paleosols has become commonplace and useful for qualitative and quantitative reconstructions of pCO₂, paleoprecipitation, paleotemperature, and seasonality. However, less work has considered how burial and diagenesis of the soils to create a paleosol has altered primary signatures and what the limitations of paleoclimate reconstruction for this time period may be. Here we present field descriptions, petrographic-, clay mineral-, and light-stable-isotope analyses of pedogenic carbonates from paleosols that span the Permo-Carboniferous transition from Lodève Basin, France, the Illinois Basin, the Pennington Formation of Tennessee, and the Abo and Bursum Formations of New Mexico. Together these basins span equatorial Pangea and show varying degrees of diagenesis. Some basins appear to preserve only qualitative signals of paleoclimate, having experienced wholesale alteration of all primary quantitative (chemical, mineralogical) information while other basins appear to have some degree of resetting of preserved information, but contain a primary signal preserved through the experience of burial diagenesis. We lay out here a strategy useful in assessing and constraining particular effects of diagenesis and what limitations may exist in paleoclimate reconstructions using Permo-Carboniferous-aged paleosols.