Sulfur isotope records around Livello Bonarelli (northern Apennines, Italy) black shale at the Cenomanian-Turonian boundary

;
• Kawamura, K.
;
• Kajiwara, Y.
;
• Wada, E.
;
• Okada, M.
;
• Kanamatsu, T.
;
• Taira, A.

Abstract

Sulfur isotope ratios for carbonate-hosted sulfate show a rapid increase (+6‰ to +9‰/m.y.) across the Livello Bonarelli black shale (Marche-Umbrian Apennines of Italy), which was deposited at the Cenomanian-Turonian boundary in the middle Cretaceous (93.5 Ma). The increase suggests that rates of pyrite burial increased substantially over the event, resulting in a decrease of 9% 27% in the oceanic reservoir of SO₄^2-. The enhanced pyrite burial may have significantly increased the flux of oxygen to the atmosphere (9 27 × 10¹⁸ mol/m.y.). Furthermore, removal of the large amount of iron associated with this process might have had a profound effect on iron cycle.