The benthic foraminiferal response to the mid-Maastrichtian event in the NW-European chalk sea of the Maastrichtian type area

  • Iris Vancoppenolle Department of Earth and Environmental Sciences, Division Geology, KU Leuven, Leuven, Belgium https://orcid.org/0000-0003-2112-235X
  • Johan Vellekoop Department of Earth and Environmental Sciences, Division Geology, KU Leuven, Leuven, Belgium; and OD Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
  • Monika Doubrawa Department of Earth and Environmental Sciences, Division Geology, KU Leuven, Leuven, Belgium https://orcid.org/0000-0003-4885-688X
  • Pim Kaskes Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
  • Matthias Sinnesael Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium; and IMCCE, CNRS, Observatoire de Paris, PSL University,Sorbonne Université, Paris, France
  • John W.M. Jagt Natuurhistorisch Museum Maastricht, Maastricht, The Netherlands
  • Philippe Claeys Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
  • Robert P. Speijer Department of Earth and Environmental Sciences, Division Geology, KU Leuven, Leuven, Belgium
Keywords: benthic foraminifera, Cretaceous chalk sea, inoceramid extinction, mid-Maastrichtian event

Abstract

The mid-Maastrichtian carbon isotope event (MME), dated at ∼69 Ma, reflects a perturbation of the global carbon cycle that, in part, correlates with the enigmatic global extinction of ‘true’ (i.e., non-tegulated) inoceramid bivalves. The mechanisms of this extinction event are still debated.

While both the inoceramid extirpation and MME have been recorded in a variety of deep-sea sites, little is known about their expression in epicontinental chalk seas. In order to study the shallow-marine signature of the MME in this epicontinental shelf sea, we have generated quantitative foraminiferal assemblage data for two quarries (Hallembaye, NE Belgium; ENCI, SE Netherlands) in the Maastrichtian type area, complemented by a species-specific benthic δ13C record. In contrast to deep-sea records, no significant changes in benthic foraminiferal assemblages and benthic foraminiferal accumulation rates are observed across the MME in the type-Maastrichtian area. At the Hallembaye quarry, the otherwise rare endobenthic species Cuneus trigona reaches a transient peak abundance of 33.3% at the onset of the MME, likely caused by a local transient change in organic matter flux to the seafloor. Nevertheless, high and near-constant species evenness shows that neither oxygen nor organic matter flux was limited across the extinction level or during the MME. Benthic foraminiferal data from the uppermost part of the studied section, above the MME, indicate a significant increase in food supply to the seafloor. Decreased amounts of terrigenous elements across this interval document a lesser riverine or aeolian influx, which means that the increased benthic productivity is linked to a different origin. Potentially, the continuous precipitation of chalk under nutrient-poor conditions in the Late Cretaceous chalk sea was enabled by efficient nutrient recycling in the water column. In shallower depositional settings, nutrient recycling took place closer to the seafloor, which allowed more organic matter to reach the bottom. These results provide insights in the importance of nutrient cycling for biological productivity in the NW-European chalk sea.

Published
2022-06-08
How to Cite
Vancoppenolle I., Vellekoop J., Doubrawa M., Kaskes P., Sinnesael M., Jagt J. W., Claeys P., & Speijer R. P. (2022). The benthic foraminiferal response to the mid-Maastrichtian event in the NW-European chalk sea of the Maastrichtian type area. Netherlands Journal of Geosciences, 101. https://doi.org/10.1017/njg.2022.10
Section
Original Articles