Wiek bezwzględny (K-Ar) granitoidów strzelińskich

Abstract

ABSOLUTE AGE OF K-Ar GRANITOIDS FROM STRZELIN (LOWER SILESIA)

Summary

K-Ar method has been used to determine absolute age of 21 rock samples from Strzelin and Żulova granitoids. The results obtained demonstrate that the granitoids constitute, as far as their age is concerned, two different massifs. The age of the Żulova granitoids amounts to 306 million years and that of the Strzelin granitoids – 280 million years. The Strzelin granitoids reveal at least two granitization phases of late Aariscanage. The first phase – developed at the Carboniferous-Permian boundary – 280 million years, the second phase, the age of which may hardly be determined – probably 257-270 million years. To the first phase belong more acid granitoids characterized by a distinct metasomatic nature, to the second one – those, which are more basic and which resemble diorites, disclosing a marked intrusive character.