RECONSTRUCTING THE LATE MISSISSIPPIAN PALEOCLIMATE: STRATIGRAPHY AND XRD ANALYSIS OF THE PENNINGTON FORMATION, SPARTA, TENNESSEE

The Late Mississippian (early Carboniferous) is an important time for paleoclimate reconstructions because it is thought to be an icehouse Earth that experienced eustatic sea level changes similar to those experienced today. While there has been a wealth of research done in the western equatorial Pangea for the Late Carboniferous and Permian, this study of the Pennington Formation, Tennessee, offers an opportunity to study less focused upon terrestrial early Carboniferous paleoenvironments from central equatorial Pangea (5-10° North), as well as the effects of diagenesis on paleoenvironmental proxies employed for paleosol research. New fieldwork on an outcrop outside Sparta, TN shows interbedded limestone and mudstone layers including four paleosol profiles that have been described and analyzed for the principle clay mineral components. The paleosols preserve typical vertic features including slickensides, mukkara and wedge-shaped peds as well as low chroma color and are thus Gleyed Vertisols. The gleyed nature of these paleosols is likely a product of incipient burial diagenesis associated with seawaters, given the stratigraphic relationships observed. The presence of Vertisols intercalated between limestones suggests a persistent influence of glacioeustacy in conjunction with highly seasonal climates during base-level lowstands and soil development which gave rise to pedoturbation and the characteristic suite of vertic morphologies seen in outcrop. This is in contrast to sites from the upper Pennsylvanian which also contain evidence for eustatic sea level change but are suggestive of more ever-wet conditions and recorded by the common occurrence of thick coal layers atop mineral-dominated paleosol profiles.