Magnetostratigraphy of the Cretaceous-Tertiary boundary at Agost (Spain)

J.J Groot,R.B.G De Jonge,C.G Langereis,W.G.H.Z Ten Kate,J Smit

doi:10.1016/0012-821x(89)90155-6

J.J Groot, R.B.G De Jonge + Show 3 more

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https://doi.org/10.1016/0012-821x(89)90155-6

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Abstract

A detailed magnetostratigraphic investigation of the Agost section (Spain) containing the Cretaceous-Tertiary (K/T) boundary is reported. Thermal demagnetization—contrary to alternating field demagnetization—succeeds in revealing the polarity of the characteristic remanent magnetization, although an overlap in blocking temperature spectrum exists with a normal polarity, secondary magnetization component. The K/T boundary occurs at two-thirds from the base of a reversed polarity zone and by comparison with earlier results [1] this polarity zone is correlated to chron C29r. Linear regression of sedimentation rates in other sections with an established magnetostratigraphy and containing the K/T boundary yields an age of 66.45 Ma for this boundary. On the basis of this age and the magnetic reversal ages of the Berggren et al. [13] polarity time scale, new first appearance (FAD) ages around the K/T boundary are suggested for the planktonic species Morozovella trinidadensis (Bolli) (66.04 Ma), Morozovella pseudobulloides (Plummer) (66.34 Ma), Eoglobigerina taurica (Bang) (66.41 Ma) and “Globigerina eugubina” Luterbacher & Premoli Silva (66.43 Ma).

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