We have demonstrated that cryogenic separation of glauconite and foraminifera from the host rock allows to preserve the integrity of extracted specimens, assures minimal damage and causes no artificial fractionation. The K/Ar dating of two glauconite samples from Cretaceous/Paleogene boundary in the Nasiłów outcrop yields 62.0 and 66.3 Ma. The discrepancy in these dates, much larger than expected from analytical precision, may result from too low %K, which was 5.91 and 5.73, respectively.
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2. Durakiewicz T., Wójtowicz A., Banaś M., Kalicka L., (1997) Isotopic composition of oxygen in Tertiary glauconites dated by K/Ar method, Materials of the “4th Session on Dating of Minerals and Rocks”, 11-12 December 1997, Lublin, 27-40.
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