Microfossils in the Ordovician erratic boulders from Southwestern Finland

Abstract

Chitinozoans, ostracods and acritarchs found in four glacially transported limestone boulders from the south-western coast of Finland have been studied in order to test the usefulness of these microfossil groups in age determinations. Also rare specimens of conodonts, inarticulated brachiopods and foraminifers were found. Baltic limestone (or Östersjö limestone) was the most problematic, because only fossils with calcitic or phosphatic shells are preserved. It is concluded that the boulders identified correlate with the Uhaku and Rakvere stages of the Middle Ordovician.

Keywords

• microfossils
• sedimentary rocks
• limestone
• erratics
• chitinozoans
• ostracods
• acritarchs
• Ordovician
• Southwestern Finland