Atmospheric pCO2 Reconstruction of Early Cretaceous Terrestrial Deposits in Texas and Oklahoma Using Pedogenic Carbonate and Occluded Organic Matter

Pedogenic carbonate samples collected from three Lower Cretaceous (Aptian–Albian) fossil localities in Texas and Oklahoma were analyzed to develop paleoatmospheric pCO2 estimates by measuring the stable carbon isotopes of pedogenic calcite their co-existing occluded organic matter. Calcite ?13C values ranged ?10.9‰ ?4.4‰ while matter ?27.3‰ ?21.1‰. These isotope measurements combined with temperature (30 °C) soil-respired CO2 concentration (839–6047 ppmV) provided atmospheric ranging 67 ppmV over 1100 ppmV. show a significant increase during late Aptian followed decrease early Albian transition period, roughly correlating OEA1b event. Given lack chronostratigraphic constraints geologic units study area, these data provide further evidence for approximate age as well pertinent paleoclimate insights into greenhouse climate conditions.