Wiek bezwzględny (K-Ar) granitoidów kłodzko-złotostockich i strefy Niemczy

Abstract

ABSOLUTE AGE OF (K-Ar) GRANITOIDS FROM THE KŁODZKO ZŁOTY STOK AREA AND THE NIEMCZA ZONESummaryBy means of K-Ar method 12 double determinations of absolute age have been made of rock samples taken from the granitoids of the Kłodzko - Złoty Stok area and the Niemcza zone in the Sudetes.The age of the granitoids from the Kłdzko - Złoty Stok area has been determined to be 295–298 million years, this corresponding to the Asturian phase of the upper Carboniferous. Of the same age are the medium-grained granitoids of the Kośmin, type from the Niemcza Zone. At the Carboniferous -Permian boundary, about 280 million years ago, tectonic movements had taken place causing, within the Kłdzko - Złoty Stok granitoids, numerous fractures and displacements, along which hydrothermal activity developed. This period has been documented by a series of samples taken from the tectonic zones. At that period some intrusions of fine-grained granitoids of the Przedborowa type penetrated the Niemcza zone.At the Rotliegendes time, which in the Sudetic region was characterized by violent volcanic activity within the Kłdzko - Złoty Stok granitoids, some portions - particularly the marginal ones – were affected by hydrothermal solutions; this process resulted in a strong serictization of feldspars and in a chloritization of dark: minerals. The average age of the rock samples taken from these portions is thought to be equal to 262 million years and it may precisely be correlated with the volcanic activity period of the Rotliegendes.