Revisiting Glauconite Geochronology: Lessons Learned from In Situ Radiometric Dating of a Glauconite-Rich Cretaceous Shelfal Sequence

Esther Scheiblhofer, Ulrike Moser*, Stefan Lӧhr, Markus Wilmsen, Juraj Farkaš, Daniela Gallhofer, Alice Matsdotter Bäckström, Thomas Zack, Andre Baldermann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The scarcity of well-preserved and directly dateable sedimentary sequences is a major impediment to inferring the Earth’s paleo-environmental evolution. The authigenic mineral glau-conite can potentially provide absolute stratigraphic ages for sedimentary sequences and constraints on paleo-depositional conditions. This requires improved approaches for measuring and interpreting glauconite formation ages. Here, glauconite from a Cretaceous shelfal sequence (Langenstein, northern Germany) was characterized using petrographical, geochemical (EMP), andmineralogical (XRD) screening methods before in situ Rb-Sr dating via LA-ICP-MS/MS. The obtained glauconite ages (~101 to 97 Ma) partly overlap with the depositional age of the Langenstein sequence (±3 Ma), but without the expected stratigraphic age progression, which we attribute to detrital and diagenetic illitic phase impurities inside the glauconites. Using a novel age deconvolu-tion approach, which combines the new Rb-Sr dataset with published K-Ar ages, we recalculate the glauconite bulk ages to obtain stratigraphically significant ‘pure’ glauconite ages (~100 to 96 Ma). Thus, our results show that pristine ages can be preserved in mineralogically complex glauconite grains even under burial diagenetic conditions (T < 65 °C; <1500 m depth), confirming that glauco-nite could be a suitable archive for paleo-environmental reconstructions and direct sediment dating.

Original languageEnglish
Article number818
Issue number7
Publication statusPublished - Jul 2022


  • diagenesis
  • glauconite
  • illitization
  • in situ Rb-Sr geochronology
  • radiometric dating

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geology

Fields of Expertise

  • Advanced Materials Science


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