MAJOR ELEMENT AND ISOTOPE GEOCHEMISTRY FROM LATE QUATERNARY PALEOSOLS IN SOUTHWESTERN KANSAS: ASSESSING CLIMATE AND PARENT MATERIAL CHANGE
Several indices derived from geochemical data were examined to assess the impact of climate and parent material on weathering. Preliminary data indicate that the most intense chemical weathering occurred during late MIS 5. Qualitative paleoclimatic conditions were inferred from stable C and O isotopes, which are supported by quantitative reconstructions of mean annual precipitation (MAP) and temperature (MAT) from major element geochemical data. Results suggest 1) relatively frequent shifts in temperature (5.3–9.1°C), precipitation (350–700 mm/yr) and potentially meteoric moisture sources during late MIS 5, 2) relatively cool (7.6°C) and dry (~550 mm/yr) conditions during MIS 4 with some evidence for fluctuations in temperature, seasonality, and/or meteoric water sources, 3) increased temperature (9.1°C) and aridity (~450 mm/yr) during MIS 3, 4) likely cool conditions during MIS 2 with sufficient effective precipitation to support C4 plant communities, and 5) relatively warm and dry climatic conditions during MIS 1. A significant shift in the isotopic signal and abundance of immobile elements was observed at ~3 m depth in both cores. This shift is interpreted to represent a change in parent material from locally derived eolian sands to more distally derived eolian silts at ca. 29 ka.