Changes

==X-compounds==

==X-compounds==

The figure below shows an example of an unusual group of alkanes called X-compounds. They contain one or more methyl branches near the middle of a long-chain hydrocarbon. These compounds originate from primitive cyanobacteria (blue-green algae) and are diagnostic of Precambrian sources.

[[file:oiloil-and-oilsource-rock-correlations_fig8-9.png|left|thumb|{{figure number|5}}From Klomp;<ref name=ch08r25>Klomp, U., 1986, The chemical structure of a pronounced series of iso-alkanes in south Oman crudes: Organic Geochemistry, vol. 10, p. 807–814., 10., 1016/S0146-6380(86)80017-1</ref> reprinted with permission from Elsevier.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-9.png|thumb|{{figure number|8-9}}From Klomp;<ref name=ch08r25>Klomp, U., 1986, The chemical structure of a pronounced series of iso-alkanes in south Oman crudes: Organic Geochemistry, vol. 10, p. 807–814., 10., 1016/S0146-6380(86)80017-1</ref> reprinted with permission from Elsevier.]]

[[:file:oiloil-and-oilsource-rock-correlations_fig8-9.png|Figure 5]] shows an example of an unusual group of alkanes called X-compounds. They contain one or more methyl branches near the middle of a long-chain hydrocarbon. These compounds originate from primitive cyanobacteria (blue-green algae) and are diagnostic of Precambrian sources.

==Resin-derived terpanes==

==Resin-derived terpanes==