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Cambrian–Ordovician Boundary beds at Tônismägi, Tallinn, North Estonia

Published online by Cambridge University Press:  01 May 2009

D. Kaljo
Affiliation:
Institute of Geology, Academy of Sciences of the Estonian S.S.R., Estonia pst. 7, Tallinn, 200101, U.S.S.R.
H. Heinsalu
Affiliation:
Institute of Geology, Academy of Sciences of the Estonian S.S.R., Estonia pst. 7, Tallinn, 200101, U.S.S.R.
K. Mens
Affiliation:
Institute of Geology, Academy of Sciences of the Estonian S.S.R., Estonia pst. 7, Tallinn, 200101, U.S.S.R.
I. Puura
Affiliation:
Institute of Geology, Academy of Sciences of the Estonian S.S.R., Estonia pst. 7, Tallinn, 200101, U.S.S.R.
V. Viira
Affiliation:
Institute of Geology, Academy of Sciences of the Estonian S.S.R., Estonia pst. 7, Tallinn, 200101, U.S.S.R.

Abstract

The Cambrian–Ordovician Boundary beds at the Tônismägi section in Tallinn, North Estonia, are represented by siltstones and sandstones with interlayers of clay and kerogenous argillites. In this section, three conodont zones – Cordylodus proavus, C. intermedius and C. rotundatus-angulatus – were established. Graptolites of the Rhabdinopora flabelliforme group were found in the upper part of the C. proavus Zone. This section demonstrates that in suitable facies, species of Rhabdinopora may appear earlier than usually considered.

Type
Articles
Copyright
Copyright © Cambridge University Press 1988

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References

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