The Late Maastrichtian Rørdal Member (Denmark): a remarkable window of climatic, environmental and biotic changes at orbital timescales

A rare climatic cooling event during the Late Maastrichtian period, coinciding with a 405 kyr insolation maximum, is documented in the Rørdal Member of Denmark's Møns Klint Formation. This discovery challenges conventional expectations by linking orbital-scale climate changes to lithological variations, such as chalk–marl cyclicity. The study employs cyclostratigraphic analysis and oxygen isotope data from bulk carbonate, benthic foraminifera, and brachiopods to reveal a prominent cooling trend aligned with eccentricity cycles. However, geochemical and calcareous nannofossil data suggest lower productivity levels, prompting an alternative deposition model involving dense water cascading and sea-level restriction rather than ocean fertilization.

Thibault, N., Lauridsen, B. W., Schovsbo, N. H., Anderskouv, K., Bjerrum, C. J., Korte, C., Martinez, M., Morigi, C., Stemmerik, L., & Ullmann, C. V. (2024). The Late Maastrichtian Rørdal Member (Denmark): a remarkable window of climatic, environmental and biotic changes at orbital timescales. Geological Society, London, Special Publications, 545(1), 399–429. https://doi.org/10.1144/sp545-2023-124