| Carbon isotope ratios are commonly measured on whole oils, kerogens, and whole extracts (bitumens) from rocks. In many cases they are also measured on the C<sub>15+</sub> saturate and aromatic fractions and are often displayed on a Sofer.<ref name=ch08r50>Sofer, Z., 1984, Stable carbon isotope compositions of crude oils: application to source depositional environments and petroleum alteration: AAPG Bulletin, vol. 68, p. 31–49.</ref> diagram (e.g., the figure on the right, below). Less commonly, carbon isotope ratios are measured on the distillate and/or chromatographic fractions. For oil-[[source rock]] correlations, isotope ratios can also be measured on kerogen. Results of isotope analyses are often presented in a socalled Galimov diagram (left, below). Carbon isotope ratios can be characteristic of geologic age and environment (e.g., <ref name=ch08r4>Chung, H., M., Rooney, M., A., Toon, M., B., Claypool, G., E., 1992, Carbon isotopic composition of marine crude oils: AAPG Bulletin, vol. 76, p. 1000–1007.</ref><ref name=ch08r5>Chung, H., M., Rooney, M., A., Toon, M., B., Claypool, G., E., Rooney, M., A., Squires, R., M., 1994, Source characteristics of marine oils as indicated by carbon isotopic ratios of volatile hydrocarbons: AAPG Bulletin, vol. 78, p. 396–408.</ref> | | Carbon isotope ratios are commonly measured on whole oils, kerogens, and whole extracts (bitumens) from rocks. In many cases they are also measured on the C<sub>15+</sub> saturate and aromatic fractions and are often displayed on a Sofer.<ref name=ch08r50>Sofer, Z., 1984, Stable carbon isotope compositions of crude oils: application to source depositional environments and petroleum alteration: AAPG Bulletin, vol. 68, p. 31–49.</ref> diagram (e.g., the figure on the right, below). Less commonly, carbon isotope ratios are measured on the distillate and/or chromatographic fractions. For oil-[[source rock]] correlations, isotope ratios can also be measured on kerogen. Results of isotope analyses are often presented in a socalled Galimov diagram (left, below). Carbon isotope ratios can be characteristic of geologic age and environment (e.g., <ref name=ch08r4>Chung, H., M., Rooney, M., A., Toon, M., B., Claypool, G., E., 1992, Carbon isotopic composition of marine crude oils: AAPG Bulletin, vol. 76, p. 1000–1007.</ref><ref name=ch08r5>Chung, H., M., Rooney, M., A., Toon, M., B., Claypool, G., E., Rooney, M., A., Squires, R., M., 1994, Source characteristics of marine oils as indicated by carbon isotopic ratios of volatile hydrocarbons: AAPG Bulletin, vol. 78, p. 396–408.</ref> |