Wiek izochronowy Rb/Sr granitu karkonoskiego z kamieniołomu Szklarska Poręba Huta oraz oznaczenie stosunku inicjalnego 87Sr/86Sr w tymże granicie

Abstract

ISOCHRONOUS AGE RB/SR OF KARKONOSZE GRANITE FROM THE QUARRY SZKLARSKA PORĘBA HUTA AND SIGNIFICANCE OF INITIAL RATIO 87SR/86SR IN THIS GRANITE Summary The intrusion of the Karkonosze Mts magma took place 328 my at the turn of Lower and Upper Carboniferous. It is possible that intrusive processes began earlier and were of pulsatory character. The Karkonosze Mts Massif exhibits some features of "S" type granite, originated in the continental crust. The low initial 87Sr /86Sr ratio (0.7064) is explained both by admixing of mantle material into the magma and by poverty of premagmatic rocks in Rb. First attempt was undertaken in order to divide the Lower Silesian granites into "I" and "S" classes. The distribution of "I" type granites coincides roughly with the strike of the axis of the fan structures arrangement in the Variscides. This line is probably an old suture after a closed basin.