Changes

==Further evidence shows oils are similar==

==Further evidence shows oils are similar==

[[file:oiloil-and-oilsource-rock-correlations_fig8-47.png|thumb|{{figure number|2}}From Hughes et al.<ref name=ch08r20 />); reprinted with permission from Norwegian Geological Society.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-47.png|thumb|300px|{{figure number|2}}(top) Ternary diagram showing the distribution of ααα-20R-steranes by carbon number. (bottom) mass chromatograms for a typical Ekofisk and Eldfisk oil. From Hughes et al.<ref name=ch08r20 />); reprinted with permission from Norwegian Geological Society.]]

Examination of correlation parameters that are more specifically source distinctive, however, suggests that the variations within the set of oils are actually minor. The distribution of C₂₇-C₂₉ regular steranes shows that most of the oils cluster rather tightly, with approximately equal concentrations of each homolog ([[:file:oiloil-and-oilsource-rock-correlations_fig8-47.png|Figure 2]]). Furthermore, Hughes et al.<ref name=ch08r20 />) report that δ¹³C values for the oils range from –28.7 ‰ to –26.8 ‰, with 28 of the 30 oils falling in the –28.3 ‰ to –27.1 ‰ range. Finally, terpane distributions show that many of the oils are very similar to one another ([[:file:oiloil-and-oilsource-rock-correlations_fig8-47.png|Figure 2]], bottom).

Examination of correlation parameters that are more specifically source distinctive, however, suggests that the variations within the set of oils are actually minor. The distribution of C₂₇-C₂₉ regular steranes shows that most of the oils cluster rather tightly, with approximately equal concentrations of each homolog ([[:file:oiloil-and-oilsource-rock-correlations_fig8-47.png|Figure 2]]). Furthermore, Hughes et al.<ref name=ch08r20 />) report that δ¹³C values for the oils range from –28.7 ‰ to –26.8 ‰, with 28 of the 30 oils falling in the –28.3 ‰ to –27.1 ‰ range. Finally, terpane distributions show that many of the oils are very similar to one another ([[:file:oiloil-and-oilsource-rock-correlations_fig8-47.png|Figure 2]], bottom).