Carbon and nitrogen of sediment core CRP-2A (Table 1)

Because Early Oligocene sediment included significant amounts of coal detritus, TOC values are higher in Early Oligocene rocks than in younger rocks. TOC values are highest in the fine-grained rocks deposited as part of the highstand systems tract (HST) and TOC values decrease from the bottom to the top of the HST.

The TOC:TN ratios observed in the CRP-2/2A core typically exceed 10, and are strong evidence that the preserved organic matter comprises a mixture of detrital coal and aquatic organic matter. Solvent-soluble organic matter comprises autochthonous bitumen derived from aquatic organic matter, allochthonous bitumen derived from deeper sedimentary rocks, and recycled bitumen derived from coal detritus.