Nunn E.V., Price G.D., Hart M.B., Page K.N., Leng M.J. (2009) Isotopic signals from Callovian - Kimmeridgian (Middle Upper Jurassic) belemnites and bulk organic carbon, Staffin Bay, Isle of Skye, Scotland // Journal of the Geological Society. V.166. P.633-664.
The stable isotope data presented here significantly extend and expand upon previous isotopic
investigations of the Middle to Late Jurassic interval. The belemnite samples collected from the Staffin Bay
and Staffin Shale formations from the Isle of Skye, Scotland, yielded oxygen isotope values consistent with Callovian–Kimmeridgian palaeotemperatures of 6.7–20.6 8C. The carbon isotope data comprise one of the first moderately high-resolution investigations of the relationship between terrestrial 13Corg (predominantly fossil wood debris) and marine 13Ccarb (belemnites) as derived from a geologically coeval record. The Staffin Bay data reveal a broad Early to Mid-Oxfordian positive carbon isotope excursion. The excursion maximum occurs in the cordatum Zone (British Boreal ammonite zonation), although high values persist into the tenuiserratum Zone. The correspondence between the marine and terrestrial records indicates a strong coupling of the ocean–atmosphere system and suggests that the total exchangeable carbon reservoir would have been affected at this time. The Mid-Oxfordian negative carbon isotope excursions identified in published Tethyan records and commonly attributed to methane release are not recorded in the Staffin Bay data, which may suggest that the Tethyan excursions do not represent fluctuations in the global carbon reservoir and that the fidelity of the methane hypothesis should be re-evaluated (addition explanations of absence of such an excursion in Staffin Bay may be connected with a) not precise correlation between Tethyan and Boreal Middle Oxfordian, because Tethyan TOC record received from ammonite-poor sections and b) with sampling gap near to densiplicatum/tenuiserratum boundary ).