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MC Kina 2024

Mikael Calner

Professor

MC Kina 2024

Insights into the K–Pg extinction aftermath: The Danish Cerithium Limestone Member

Author

  • Tjördis Störling
  • Isaline Demangel
  • Anders Lindskog
  • J. Andersson
  • Mikael Calner
  • Daniel Conley
  • Sylvain Richoz

Summary, in English

The Cretaceous–Palaeogene (K–Pg) mass extinction about 66 Ma ago was one of Earth’s largest mass extinction events. The demise of calcifiers, among others, influenced biogeochemical cycles and changed the conditions for carbonate depo sition in the global ocean. This study addresses the sedimentology and carbonate microfacies of the Cerithium Limestone Member of the Rødvig Formation within the renowned Stevns Klint succession in Denmark. The limestone was deposited in the earliest Danian Stage, immediately after the K–Pg mass extinction. It is a pale yellow, partly cemented unit with a dense network of Thalassinoides burrows and numerous flint nodules. Studies of the thin sections revealed that the Cerithium Limestone Member is more variable than expected from its overall homogeneous appearance at the macroscopic scale. The thin sections and scanning electron mi croscope (SEM) images showed that the highly bioturbated limestone consists of four principal microfacies: a mudstone, a wackestone and two different packstones. The 30 to 120-cm thick Cerithium Limestone Member fills depressions between low-amplitude mounds in the Maastrichtian chalk. The lowermost part constitutes a thin layer of a bryozoan-rich packstone, probably reworked from the crests of the Maastrichtian mounds. The successive part of the member is dominated by wacke stone with mainly foraminifera (planktic and benthic), molluscs and echinoderm debris, and in some areas an abundance of peloids. The foraminifera- and mollusc rich packstone appears in lenses. The mudstone contains few foraminifera and is linked to burrows and syn-sedimentary fractures. SEM observations revealed that the Cerithium Limestone Member corresponds to a dispersed micrite, with small calcite crystals ~1–4 µm in size. The general shape of these calcite crystals suggests precipitation from cyanobacterial activity and, thus, a microbial genesis for the micrite of the Cerithium Limestone Member.

Department/s

  • Lithosphere and Biosphere Science
  • Department of Geology
  • Quaternary Sciences

Publishing year

2024-11-13

Language

English

Pages

175-191

Publication/Series

Bulletin of the Geological Society of Denmark

Volume

73

Document type

Journal article

Publisher

Dansk Geologisk Forening

Topic

  • Geology

Keywords

  • Cerithium Limestone Member
  • microbial micrite
  • Stevns Klint
  • Danian
  • Thin sections
  • Carbonate
  • Microfacies
  • Cretaceous–Palaeogene boundary

Status

Published

ISBN/ISSN/Other

  • ISSN: 0011-6297