Episjenity a perspektywy występowania śródgranitowych złóż uranu w masywie Karkonoszy
Abstract
EPISYENITES AND PERSPECTIVES OF OCCURRENCE OF INTERGRANITE URANIUM DEPOSITS IN THE KARKONOSZE MASSIF
Summary
The Karkonosze granite massif (Lower Silesia) is one of the best known massifs petrographically and tectonically. Detailed sampling performed by one of the authors revealed the presence of rocks which - with their granite structure - are characterized by the lack of quartz and marked porosity, or the presence of secondary quartz of specific milky colour. These rocks form small, irregular bodies occurring within normal granite. These bodies a:re clearly younger than the granite since, in some places, they were also formed from aplites cutting the granite. The mineral and chemical composition (Table 1), the mode of occurrrence and conditions of origin of these rocks resemble those of episyenites (that is rocks with syenite composition but formed from normal granite in result of subsequent alterations) from the Central Massif and Vendee areas of France. Three types of episyenites were differentiated: potassium-sodium, potassium and sodium.
Episyenites of the Central Massif and Vendee have great metalogenic importance as about one third of uranium deposits in these important; uranium provinces is connected with these rocks. It was found out that in the Karkonosze area the mineralization points where already in the last century uranium minerals were recorded are connected with episyenites. The presence of episyenites and earlier detected presence of uraninite microgrowths point to the existence of marked analogy between Karkonosze granite and uranium-bearing granite massifs in France, thus indicating the possibility of occurrence of intragranite uranium deposits in the Karkonosze massif.
Summary
The Karkonosze granite massif (Lower Silesia) is one of the best known massifs petrographically and tectonically. Detailed sampling performed by one of the authors revealed the presence of rocks which - with their granite structure - are characterized by the lack of quartz and marked porosity, or the presence of secondary quartz of specific milky colour. These rocks form small, irregular bodies occurring within normal granite. These bodies a:re clearly younger than the granite since, in some places, they were also formed from aplites cutting the granite. The mineral and chemical composition (Table 1), the mode of occurrrence and conditions of origin of these rocks resemble those of episyenites (that is rocks with syenite composition but formed from normal granite in result of subsequent alterations) from the Central Massif and Vendee areas of France. Three types of episyenites were differentiated: potassium-sodium, potassium and sodium.
Episyenites of the Central Massif and Vendee have great metalogenic importance as about one third of uranium deposits in these important; uranium provinces is connected with these rocks. It was found out that in the Karkonosze area the mineralization points where already in the last century uranium minerals were recorded are connected with episyenites. The presence of episyenites and earlier detected presence of uraninite microgrowths point to the existence of marked analogy between Karkonosze granite and uranium-bearing granite massifs in France, thus indicating the possibility of occurrence of intragranite uranium deposits in the Karkonosze massif.