Stable isotope geochemistry of crude oils and of possible source rocks from New Zealand. 2.: Sulfur.
In: Applied Geochemistry (Appl.Geochem.), Jg. 4 (1989) ; Nr. 2, S. 121-130
Zeitschriftenaufsatz / Fach: Chemie
The S isotopic compns. of New Zealand low-S crude oils and components (asphaltenes, absorptive filtration fractions) and source rock components (extd. hydrocarbons, kerogen, pyrite, sulfates) were detd. Oils from the Taranaki Basin have d34S values +3 to +14.permill.; the lower values possibly represent plant assimilation of fresh water sulfate. Higher values, particularly those from the West Coast Basin (around +20.permill.) suggest closed ocean basin conditions (or fast sedimentation rate) whereas neg. d34S values from East Coast Basin suggest open ocean (or low sedimentation rate) conditions. It is suggested that an oil-source rock genetic relation should show as a similarity in d34S values for total oil and source rock ext., kerogen, and pyrite. Shale samples analyzed plot outside the corresponding oil range and cannot be considered possible source rocks. However, coal samples from the Maui-4 well and Nelson outcrops show strong isotopic correlations with the Taranaki oils.