Changes

After establishing the NL oils as a single type, Clayton and Koncz<ref name=ch08r6 /> determined the source potential for the available sedimentary section using 26 core samples and attempted to correlate the NL oils to each of the possible sources. Just as the first screening step for the oil–oil correlation involved δ¹³C values of the aliphatic and aromatic hydrocarbons, the first screening step for the oil–source rock correlation effort involved comparing δ¹³C of the whole oils and bitumens from the source candidates. Their results indicate that two potential sources [the Upper Triassic Kössen Marl and the Sarmatian (middle Miocene) shales] have very similar δ¹³C values. When these carbon isotope data are combined with oleanane–hopane ratios and C₂₇–C₂₉ sterane distributions, cluster analysis comparison supports a dominantly Upper Triassic source for the NL oils, with possibly a minor contribution from the Sarmatian (middle Miocene) shales.

After establishing the NL oils as a single type, Clayton and Koncz<ref name=ch08r6 /> determined the source potential for the available sedimentary section using 26 core samples and attempted to correlate the NL oils to each of the possible sources. Just as the first screening step for the oil–oil correlation involved δ¹³C values of the aliphatic and aromatic hydrocarbons, the first screening step for the oil–source rock correlation effort involved comparing δ¹³C of the whole oils and bitumens from the source candidates. Their results indicate that two potential sources [the Upper Triassic Kössen Marl and the Sarmatian (middle Miocene) shales] have very similar δ¹³C values. When these carbon isotope data are combined with oleanane–hopane ratios and C₂₇–C₂₉ sterane distributions, cluster analysis comparison supports a dominantly Upper Triassic source for the NL oils, with possibly a minor contribution from the Sarmatian (middle Miocene) shales.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-52.png|Figure 2]] shows isotope data used to support [[oil–oil and oil–source rock correlation]]s for the NL oils of the Zala basin. The Sofer plot (left) distinguishes the NL oils from the Szil and Szen types, since the NL oils are significantly lighter isotopically. The data on the right (including data compiled by <ref name=ch08r27>Koncz, I., 1990, The origin of the oil at the Nagylengyel and nearby fields [in Hungarian]: Általános Földtani Szemk, vol. 25, p. 55–82.</ref> show that only the Upper Triassic and Sarmatian (middle Miocene) units are isotopically similar to the NL oils.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-52.png|Figure 2]] shows isotope data used to support [[oil–oil and oil–source rock correlation]]s for the NL oils of the Zala basin. The Sofer plot (left) distinguishes the NL oils from the Szil and Szen types, since the NL oils are significantly lighter isotopically. The data on the right (including data compiled by Koncz<ref name=ch08r27>Koncz, I., 1990, The origin of the oil at the Nagylengyel and nearby fields [in Hungarian]: Általános Földtani Szemk, vol. 25, p. 55–82.</ref> show that only the Upper Triassic and Sarmatian (middle Miocene) units are isotopically similar to the NL oils.

==Using geological data to refine the correlation==

==Using geological data to refine the correlation==