Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 5. 1974. (Budapest, 1974)

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1 / X / Y Fig. 3. The postponement of appearance data fo the Oligocène planktonic Foraminifera. 3. ábra. Az oligocénben megjelenő plankton foraminiferák megjelenési adatainak eltolódása. that in Europe the Globigerina ampliapertura Zone represents the lower, and the Globorotalia opima opima Zone the upper part of the Upper Oligocène. But even at that time on Trinidad - owing to the higher evolution rate - the sediments of the Globigerina ciperoensis ciperoensis and perhaps the Globoratalia kugleri Zones were deposited. Consequently, the Globorotalia opima opima Zone, for example, in Trinidad and in Europe is asynchronous. It is obvious on the basis of the above mentioned facts that there are no species in the Central European Oligocène with synchronous appearance in the tropical and boreal regions. These differences evidently affect the planktonic zonation. The possible solution is that suggested by JENKINS (1973), i.e. according to the climatic belts, different zonation is needed for the tropical - Mediterranean, temperate and - extending the suggestions of JENKINS - to boreal regions. The study of the transitional areas of these regions could make the correlation of the different zonations possible. On the other hand the absolute age determinations of the planktonic foraminifer data cannot be neglected, because without that the biostratigraphy has no real foundation.