The early Katian (Late Ordovician) reefs near Saku, northern Estonia and the age of the Saku Member, Vasalemma Formation

Research output: Contribution to journalArticle


Reefs developed simultaneously during the latest Sandbian/earliest Katian global Guttenberg Isotopic Carbon Excursion (GICE) in several places across Baltoscandia. Latest Sandbian/earliest Katian patch reefs are also described from the Vasalemma Formation of northern Estonia. The Saku Member of the Vasalemma Formation was previously considered as a proximal facies related to the reefs. However, the Saku Member clearly post-dates the GICE interval and ranges from the latest Keila to Rakvere in terms of regional stages. Some small reefs occur in direct proximity to the stratotype of the Saku Member. New delta C-13 data from the stratotype section and the adjacent reefs indicate that these reefs developed before the deposition of the Saku Member during the GICE interval. The chemostratigraphic data support the hypothesis of a short-time Baltoscandian reef growth event that terminated during the GICE interval.


  • Bjorn Kroger
  • Linda Hints
  • Oliver Lehnert
  • Peep Mannik
  • Michael Joachimski
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Geology


  • carbon isotopes, GICE excursion, Kope excursion, Ordovician reefs, Oandu, Stage, Estonia
Original languageEnglish
Pages (from-to)271-276
JournalEstonian Journal of Earth Sciences
Issue number4
Publication statusPublished - 2014
Publication categoryResearch