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The lower Maastrichtian Hivdskud succession, Møns Klint, Denmark: calcareous nannofossil biostratigraphy, carbon isotope stratigraphy, and bulk and brachiopod oxygen isotopes

Publikation: Forskning - fagfællebedømtTidsskriftartikel

Dokumenter

M.E. Jelby, Nicolas Rudolph Thibault, Finn Surlyk, Clemens Vinzenz Ullmann, Rikke Harlou, Christoph Korte

A new calcareous nannofossil and δ13C stratigraphy is established for the chalk exposed in the lower Maastrichtian Hvidskud succession, Møns Klint, Denmark. It is based on 21 nannofossil samples and analysis of 82 stable isotope samples, allowing correlation with a previously established brachiopod zonation. The succession, which belongs to the brachiopod spinosa-subtilis to pulchellus-pulchellus zones, extends upwards from calcareous nannofossil subzone UC16ii to UC19ii and encompasses δ13C events M1+ to M2+. A new chronostratigraphic and geochronological age model is proposed based on correlation with the cored boreholes Stevns-1 (Denmark) and ODP Site 762C (Indian Ocean). Hvidskud encompasses the 405 kyr eccentricity cycles Ma40513 – Ma40511 within magnetochron C31r. A sedimentation rate of 5.0 cm kyr-1 can be inferred from correlation to geochronological tie-points in ODP 762C, suggesting an age of ~70.9 Ma for the base of the succession and a duration of >680 kyr for the investigated interval. The Hvidskud succession is well-exposed, easily accessible, and the new stratigraphic framework and precise age model suggest that it can be used as a key locality for stratigraphic correlation of the lower Maastrichtian in north-western Europe. Information on palaeo-seawater temperatures can be drawn from oxygen isotope records obtained from bulk rock samples and 24 micromorphic brachiopod specimens (Terebratulina faujasii). The brachiopod data show a clear diagenetic trend but point to an upper range of unaltered values between –0.4 and –0.6‰. Assuming a δ18O value of –1‰ for seawater in a Cretaceous ice-free world, this would indicate bottom water temperatures of 13.6 to 14.3°C of the Danish Chalk Sea (45°N) during the early Maastrichtian cooling.
OriginalsprogEngelsk
TidsskriftBulletin of the Geological Society of Denmark
Vol/bind62
Sider (fra-til)89-104
Antal sider16
ISSN0011-6297
StatusUdgivet - 28 nov. 2014

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