TY - JOUR

T1 - RELIABILITY OF CALCAREOUS NANNOFOSSIL LAST CONSISTENT OCCURRENCES IN THE CHALK: AN EXAMPLE FROM THE LATE CRETACEOUS OF DENMARK

AU - Thibault, Nicolas

PY - 2016

Y1 - 2016

N2 - Calcareous nannofossil biostratigraphic results from the Rørdal-1 core (N Jutland, Denmark) have been improved with a greater sample density and compared to the late Campanian–Maastrichtian record from the Stevns-1 borehole (Sjælland, Denmark); the reference for this stratigraphic interval in the Danish Basin. This study supports the idea that a large number of inconsistent, very rare or single occurrences are essentially due to reworking, a very common process in the chalk, and that, even when examined with care, the choice of a reliable last occurrence (LO) is a challenging task. However, using absolute and semi-quantitative abundances, it is possible to establish criteria for defining seven last consistent occurrences (LCO) in the upper Campanian to lower Maastrichtian interval. The reliability of the defined LCOs is demonstrated by the excellent concordance in the correlation of these bio-events and of the carbon isotope records of Stevns-1 and Rørdal-1. The difficulty with applying previous standard nannofossil biozonation schemes for the Boreal realm and the North Sea to the Danish Basin is subsequently pointed out, and the robustness of a recently erected biozonation scheme for the Danish and North German Basins is discussed.

AB - Calcareous nannofossil biostratigraphic results from the Rørdal-1 core (N Jutland, Denmark) have been improved with a greater sample density and compared to the late Campanian–Maastrichtian record from the Stevns-1 borehole (Sjælland, Denmark); the reference for this stratigraphic interval in the Danish Basin. This study supports the idea that a large number of inconsistent, very rare or single occurrences are essentially due to reworking, a very common process in the chalk, and that, even when examined with care, the choice of a reliable last occurrence (LO) is a challenging task. However, using absolute and semi-quantitative abundances, it is possible to establish criteria for defining seven last consistent occurrences (LCO) in the upper Campanian to lower Maastrichtian interval. The reliability of the defined LCOs is demonstrated by the excellent concordance in the correlation of these bio-events and of the carbon isotope records of Stevns-1 and Rørdal-1. The difficulty with applying previous standard nannofossil biozonation schemes for the Boreal realm and the North Sea to the Danish Basin is subsequently pointed out, and the robustness of a recently erected biozonation scheme for the Danish and North German Basins is discussed.

UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=BIOSIS&KeyUT=BIOSIS:PREV201700603452&KeyUID=BIOSIS:PREV201700603452

M3 - Journal article

SP - 299

EP - 306

JO - Bulletin of the New Mexico Museum of Natural History and Science

JF - Bulletin of the New Mexico Museum of Natural History and Science

ER -