Oxygen isotope palaeotemperatures from the Tertiary period in the North Sea area

Abstract

THE understanding of global temperature conditions during the Tertiary period has greatly increased in the past decade owing to the successful oxygen isotope investigations of the numerous deep sea cores now available. Little attention has been paid, however, to applying the method to material from shelf sea areas, where the temperature-induced 18O-record in carbonate shells are generally believed to be superimposed by 18O-variations in water composition and by postdepositional alterations. This is unfortunate, as oxygen isotope data from coastal areas provide the best way of comparing traditional palaeoclimatological methods with the oxygen isotope procedure. The present study, which deals with the oxygen isotope composition of shell material from the Tertiary North Sea area, was initiated to overcome this lack of data. Here the oxygen isotope results are interpreted as palaeotemperatures and the first isotopic palaeotemperature curve for the Tertiary period in NW Europe is given.