Organic carbon losses during burial and thermal maturation of normal marine shales

The percentage of organic carbon lost during the burial diagenesis of normal marine shales (those originally deposited in oxygenated bottom waters) can be estimated by using the ratio of organic carbon (C) to pyrite sulfur (S) and assuming that the mean initial burial value of C/S for such sediments has been approximately constant since the Devonian. Plots of mean C/S vs. vitrinite reflectance (R/sub 0/) for some sedimentary basins of Jurassic and Carboniferous age show a monotonic decrease of C/S with increasing R/sub 0/.macrofossils.