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Employment of Non-Traditional Techniques to Improve Stratigraphic Correlation in the Ogallala Formation and their Applications for Future Groundwater Management

Russell Harlow, Luis Gonzales, Greg Ludvigson, and Michael Petronis

Stratigraphic investigation of the High Plains Succession (HPS) in western Kansas (Neogene Ogallala Formation and overlying, undifferentiated units) has been deficient due to lack of outcrops, regional marker beds, and its unconsolidated nature. These obstructions are significant because they have limited the reliability of stratigraphic correlations in the High Plains aquifer, the most important regional aquifer in the United States for agricultural production. Without reliable stratigraphic correlations, the characterization of hydrogeologic properties of aquifer materials and predictive models for the management of remaining groundwater resources have significant uncertainties. Due to the highly variable lithologic nature of the HPS, non-traditional stratigraphic analysis offers the promise of improved correlations; these approaches include paleoclimatology, geochemistry, and alluvial sequence stratigraphy. With state-of-the-art rotary-vibratory and hydraulic piston coring technology, we have recovered the first-ever intact drill core (HP1A) of the HPS in Haskell County of southwestern Kansas for such analysis. Chemostratigraphic results show a systematic relationship between bulk sedimentary organic matter (SOM) δ13C and pedogenic carbonate δ13C and δ18O related to biomass changes and paleoclimate variability; additionally, the fine-scale chemostratigraphic structure offers prospects for future regional correlations. HP1A sedimentary facies associations and fluvial aggradational cycle (FAC) stacking patterns reveal ten FAC-sets and two complete fluvial sequence. FAC-set boundaries and fluvial sequence boundaries have the potential to be regionally correlatable datums. Five additional cores are planned and, together, their high-resolution paleoclimatic and depositional interpretations may prove useful for future regional correlations and allow for improved stratigraphic correlation in the Ogallala Formation and inform hydrogeologic modeling. 

AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013