USE OF CARBON ISOTOPES IN PALEOSOLS AS AN INDICATOR OF THE P(CO2) OF THE PALEOATMOSPHERE

Measurements of carbon isotopic composition of coexisting paleosol organic matter and carbonate results in improved estimates of the paleo-P(CO2) content of the paleoatmosphere. Measurements from Tertiary paleosols indicate that the levels of CO2 in the early Eocene, middle and late Miocene, and Pliocene were less than 1000 ppmV. Early Cretaceous levels of P(CO2) were significantly higher, of the order of 1500 to 3000 ppmV.