PRELIMINARY REPORT ON PALEOSOLS IN THE DEER CREEK LIMESTONE FORMATION, LATE PENNSYLVANIAN, EASTERN KANSAS: EVALUATING CYCLOTHEM PALEOCLIMATIC AND PALEOHYDROLOGIC CHANGES

Evidence of subaerial exposure is used extensively to define unconformable surfaces. Previous research on subaerial exposures and paleosols has been conducted on cyclothems in the North American midcontinent; however, detailed studies of paleosol development or ichnology are uncommon. The objectives of this study are to test if transgressions are characterized by seasonally wet conditions and if regressions are characterized by arid or semiarid conditions during the Late Pennsylvanian (Virgilian), as recorded by paleosols and/or unconformities. The Upper Pennsylvanian Deer Creek Limestone Formation (DCL) in eastern Kansas (KS) was focus of this study using outcrop and geochemical analyses. During the Virgilian the DCL was deposited near-equatorial on a broad low-relief shelf and now outcrops from west-central Iowa to southern Oklahoma and contains the basal Ozawkie Limestone (OLM), Oskaloosa Shale (OSM), Rock Bluff Limestone (RBL), Larsh-Burroak Shale (LBS), and uppermost Ervine Creek Limestone (ECL) members. The Tecumseh Shale and Calhoun Shale formations bound the DCL. Paleosols, rhizoliths, and lithology were described from twelve measured sections in Douglas, Jefferson, Osage, and Shawnee counties in eastern KS. The OLM is a packstone, composed of micritic clasts, forams, crinoid stems, rugose corals, gastropods, and brachiopods. The OSM is a calcareous siltstone composed of angular blocky peds. The RBL is a thin wackestone, composed of marine shells similar to the OLM. The LBS consists of a basal fissile black shale bed and capped by a siltstone. The ECL is a wackestone with crinoid stems, forams, brachiopods, rhizoliths, and autoclastic breccia. Previously the DCL was interpreted as being deposited in a single cyclothem; however, there is evidence of two or more transgression and regression events, as the OLM in parts of the study area contain a thin shale bed. The upper OLM contains Skolithos and at the top of the bed abundant rhizoliths, caliche nodules, laminated crust, and autoclastic breccia. The lower OLM contains few rhizoliths and micritic clasts throughout. The RBL and LBS lack any subaerial exposure features. The ECL subaerial exposure features are not as extensive as in the OLM, suggesting shorter exposure time. These results will aid localized paleoclimate trends in the Late Pennsylvanian.