Changes

==Biodegradation limitations==

==Biodegradation limitations==

[[file:oiloil-and-oilsource-rock-correlations_fig8-20.png|300px|thumb|{{figure number|16}}(left) Gas chromatograms of three oils from a common source in central Myanmar. A waxy oil (top) is sequentially converted into an extremely biodegraded remnant oil (bottom). (right) Whole-oil gas chromatograms of three oils from the offshore Mackenzie Delta, northwestern Canada, showing a modest decrease in the pristane–phytane ratio, apparently as the result of minor biodegradation. From Curiale et al.;<ref name=ch08r12>Curiale, J., A., 1994, [http://archives.datapages.com/data/specpubs/methodo2/data/a077/a077/0001/0250/0251.htm Correlation of oils and source rocks—a conceptual and historical perspective], in Magoon, L., B., Dow, W., G., eds., The [[Petroleum system]]—From Source to Trap: [http://store.aapg.org/detail.aspx?id=1022 AAPG Memoir 60], p. 251–260.</ref> and Curiale<ref name=ch08r9>Curiale, J., A., 1991, The petroleum geochemistry of Canadian Beaufort Tertiary “non-marine” oils: Chemical Geology, vol. 93, p. 21–45., 10., 1016/0009-2541(91)90062-V</ref> reprinted with permission from Elsevier.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-20.png|400px|thumb|{{figure number|16}}(left) Gas chromatograms of three oils from a common source in central Myanmar. A waxy oil (top) is sequentially converted into an extremely biodegraded remnant oil (bottom). (right) Whole-oil gas chromatograms of three oils from the offshore Mackenzie Delta, northwestern Canada, showing a modest decrease in the pristane–phytane ratio, apparently as the result of minor biodegradation. From Curiale et al.;<ref name=ch08r12>Curiale, J., A., 1994, [http://archives.datapages.com/data/specpubs/methodo2/data/a077/a077/0001/0250/0251.htm Correlation of oils and source rocks—a conceptual and historical perspective], in Magoon, L., B., Dow, W., G., eds., The [[Petroleum system]]—From Source to Trap: [http://store.aapg.org/detail.aspx?id=1022 AAPG Memoir 60], p. 251–260.</ref> and Curiale<ref name=ch08r9>Curiale, J., A., 1991, The petroleum geochemistry of Canadian Beaufort Tertiary “non-marine” oils: Chemical Geology, vol. 93, p. 21–45., 10., 1016/0009-2541(91)90062-V</ref> reprinted with permission from Elsevier.]]

Biodegradation can severely alter gas chromatograms. In the earliest stages of biodegradation, ''n''-alkanes are removed selectively, leading to significant loss of information.

Biodegradation can severely alter gas chromatograms. In the earliest stages of biodegradation, ''n''-alkanes are removed selectively, leading to significant loss of information.