EGU21-4806
https://doi.org/10.5194/egusphere-egu21-4806
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cyclostratigraphy of a type-Maastrichtian chalk record, based on high-resolution geochemical analysis of the Gulpen Formation, NE Belgium 

Jarno Huygh1, Johan Vellekoop1,2, Matthias Sinnesael3, Pim Kaskes1, John Jagt4, and Philippe Claeys1
Jarno Huygh et al.
  • 1Department of Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, 1050 Brussels, Belgium (jarno.johan.huygh@vub.be)
  • 2Department of Earth and Environmental Sciences, Division of Geology, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium
  • 3Department of Earth Sciences, Mountjoy Site, Durham University, Durham DH1 3LE, United Kingdom
  • 4Natuurhistorisch Museum Maastricht, 6211 KJ Maastricht, the Netherlands

Cyclostratigraphic studies on carbonate successions have proved invaluable for understanding palaeoclimate and for constructing improved, high-resolution age models of the Late Cretaceous. Whereas carbonate strata from the type-Maastrichtian from the Netherlands and Belgium have provided a wealth of palaeontological data, so far, dating of these deposits has relied mainly on biostratigraphy and preliminary attempts at cyclostratigraphy. The existing basic cyclostratigraphic framework is based principally on apparent cyclic variations in bioclast composition and suggested Milankovitch-paced flint cycles. Until now, these strata have not yet been examined using a cyclostratigraphic approach based on high-resolution multi-proxy geochemical data sets. Within the scope of the Maastrichtian Geoheritage Project, we attempt to construct an improved astrochronological age model for Maastrichtian chalk deposits of the Gulpen Formation.

We have carried out a high-resolution elemental composition analysis of the Lower to Middle Maastrichtian chalk succession exposed at the Hallembaye (Kreco) quarry, NE Belgium. Approximately 460 chalk samples were collected every 5 cm over a 23-metre-thick stratigraphic interval and analysed as homogenised powders using micro X-ray fluorescence. This extensive elemental data set is used to evaluate (regular) changes in palaeoenvironmental conditions over time. Additionally, stratigraphic comparison of variations in elemental concentrations in the chalk with the occurrence of flint layers provides insights into potential diagenetic alterations. 

Preliminary results display promising trends with potential for the development of a cyclostratigraphic age model for the Gulpen Formation. Significant correlation between the main matrix elements calcium and silica might suggest a relationship between silica-depleted chalk and occurring flint layers throughout the chalk succession. Additionally, observed rhythmic variations in elements including - but not limited to - titanium, aluminium and potassium might exemplify changing palaeoenvironmental conditions. This improved astrochronological age model can be compared with age-equivalent astrochronologies and will, in combination with ongoing carbon isotope stratigraphy work, enable a better dating of the geological and biological records from the type-Maastrichtian. 

How to cite: Huygh, J., Vellekoop, J., Sinnesael, M., Kaskes, P., Jagt, J., and Claeys, P.: Cyclostratigraphy of a type-Maastrichtian chalk record, based on high-resolution geochemical analysis of the Gulpen Formation, NE Belgium , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4806, https://doi.org/10.5194/egusphere-egu21-4806, 2021.

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