Estimates of pCO2 in deep time provide fundamental constraints on ancient atmospheric conditions, yet can include considerable uncertainty because of variability related to distinct carbon sources. To better constrain the role of different OM sources on pCO2 estimates derived from pedogenic carbonate, Myers et al. use a range of sources of organic matter to estimate the concentration of carbon dioxide in the atmosphere in both modern and Jurassic soils. The results indicate that the pedogenic carbonate CO2 paleobarometer is sensitive to variation in stable carbon isotope composition of soil-respired CO2. Additionally, organic matter occluded in pedogenic calcite produces reasonable pCO2 estimates.
Effects of different organic-matter sources on estimates of atmospheric and soil pCO2 using pedogenic carbonate by Timothy S. Myers, Neil J. Tabor, Louis L. Jacobs, and Robert Bussert