Naturalna promieniotwórczość biotytów z granitoidów strzegomskich i strzelińskich

Abstract

NATURAL RADIOACTIVITY OF BIOTITES FROM THE STRZEGOM AND STRZELIN GRANITOIDS

Summary

Long-lasting a b, and g-activity of biotites from the Strzegom and Strzelin granitoids has been measured. Biotite samples taken for examinations come from biotite granites, which are the main rock variety of both massifs. Granites, the composition of which is equel to that of adamelite occuring in the Strzegom region, have been called granites of Kostrza type. Granites disclosing granodiorite composition, concentrated round the Sobótka Mt., have been determined as granites of Chwałków type (S. Kural, T. Morawski, 1968). The measurements of a, b, and g-radioactivity of the minerals examined have been made using scintillation probe with amplifier, adapted to work with a transistor computer. Natural a-activity of the biotite samples has been measured by means of the method of absolute measurements, worked out according to Evans formula (Evans R. D. 1934). For determination of b and g-radioaictivity of biotites relative methods of measurements have been applied.

The examinations demonstrate that the biotites from the granites of Kostrza type are richer in riadioactive elements, as compared with the biotites found in the region of Chwałków. On the other hand, the radioaetivity of biotites from the Strzelin granitoids does not show any regional differentiation.
The biotites from the Strzegom granitoids are considerably more radioactive than the Strzelin biotites. This can distinctly be seen in the case of the intensity of a-radioactivity. The radioactivity within the Strzegom massif area is irregularly distributed, the biotites from the granites of Kostrza type are more radioadive than those of the granites of Chwałków type. Extremal values of radioactivity are noted rather in samples taken within the marginail. zones of the massifs.