High-resolution late Maastrichtian–early Danian oceanic ⁸⁷Sr/⁸⁶Sr record: Implications for Cretaceous-Tertiary boundary events Available to Purchase

A high-resolution late Maastrichtian–early Danian seawater ⁸⁷Sr/⁸⁶Sr reference curve is constructed from two Cretaceous-Tertiary boundary (K-T boundary) sections: Bidart (France) and El Kef (Tunisia). The ⁸⁷Sr/⁸⁶Sr curve shows maxima at 0.3–0.4 Ma before the K-T boundary and at the K-T boundary. The first maximum could mark the onset of a major outflow of the Deccan Traps. The second maximum, a rapid 0.000 06 ⁸⁷Sr/⁸⁶Sr, shift, extends from ∼3–4 m below to ∼1 m above the K-T boundary. This profile probably results from diagenetic smoothing of an originally sharp K-T boundary ⁸⁷Sr/⁸⁶Sr anomaly, rather than from a gradual process. The sharp shift could result from (1) the vaporization of the Chicxulub target rocks, (2) global wildfires, and (3) acid-rain leaching of soils and sialic surface rocks. Of these three possibilities, only Sr release by soil leaching combined with increased rainfall associated with the K-T event appears to be sufficiently large to produce the observed K-T ⁸⁷Sr/⁸⁶Sr anomaly.