Re-Os geochronology and fingerprinting of United Kingdom Atlantic margin oil: Temporal implications for regional petroleum systems

We demonstrate that the Re-Os system can be used to understand the temporal evolution of a petroleum system as well as aid in the identification of source units. Traditional geochemical methods (high-performance liquid chromatography, carbon isotope, gas chromatography, and biomarker analysis) indicate that the main source of 18 oils analyzed for Re-Os geochronology from the United Kingdom Atlantic margin (Clair, Schiehallion, Cuillin, and Foinaven fields) is Late Jurassic marine shales. This is supported by the Os isotopic composition (Os-187/Os-188) of the Late Jurassic source (similar to 0.9-2.4) at the timing of oil generation being similar to that of the oil (68 Ma; 0.92-1.12), indicating that the Re-Os system can potentially be used to fingerprint the source of an oil. The Re-Os data for the 18 oils yield an age (68 +/- 13 Ma) that agrees with both the relative (basin models) and absolute (Ar-Ar geochronology) timing of oil generation, indicating that that Re-Os oil geochronology records oil generation events.