Changes

==Resin-derived terpanes==

==Resin-derived terpanes==

[[file:oiloil-and-oilsource-rock-correlations_fig8-10.png|thumb|{{figure number|6}}. Copyright: Unocal.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-10.png|thumb|{{figure number|6}}Chromatogram of the saturated hydrocarbons from a rock extract showing minor amounts of sesquiterpanes (the cluster of peaks eluting near ''n''-C₁₅) and large amounts of diterpanes (the small cluster of peaks eluting near ''n''-C₂₀). Copyright: Unocal.]]

Sesquiterpanes and diterpanes, derived principally from the resin in terrestrial plants of the Late Cretaceous and Cenozoic, are often abundant in younger samples with terrestrial plant input. In such cases, they usually can be seen (although not interpreted in detail) using gas chromatography. The chromatogram in [[:file:oiloil-and-oilsource-rock-correlations_fig8-10.png|Figure 6]] of the saturated hydrocarbons from a rock extract shows minor amounts of sesquiterpanes (the cluster of peaks eluting near ''n''-C₁₅) and large amounts of diterpanes (the small cluster of peaks eluting near ''n''-C₂₀). Samples containing sesqui- and diterpanes often display other characteristics of terrestrially influenced samples, such as odd-carbon preferences, high wax contents, and high pristane–phytane ratios. To analyze the resin-derived terpanes in detail, however, we should use GC/MS.

Sesquiterpanes and diterpanes, derived principally from the resin in terrestrial plants of the Late Cretaceous and Cenozoic, are often abundant in younger samples with terrestrial plant input. In such cases, they usually can be seen (although not interpreted in detail) using gas chromatography. The chromatogram in [[:file:oiloil-and-oilsource-rock-correlations_fig8-10.png|Figure 6]] of the saturated hydrocarbons from a rock extract shows minor amounts of sesquiterpanes (the cluster of peaks eluting near ''n''-C₁₅) and large amounts of diterpanes (the small cluster of peaks eluting near ''n''-C₂₀). Samples containing sesqui- and diterpanes often display other characteristics of terrestrially influenced samples, such as odd-carbon preferences, high wax contents, and high pristane–phytane ratios. To analyze the resin-derived terpanes in detail, however, we should use GC/MS.