Zmiany wtórne w porfirach okolic Wałbrzycha

Andrzej Paulo

Abstract


SECONDARY ALTERATIONS IN PORPHYRIES OF THE WAŁBRZYCH REGION

Summary

In the Upper Carboniferous porphyry intrusions occurring in the Wałbrzych trough (Lower Silesia), silicification, diockitization, dolomitization and sericitization zones have been ascertained. Altered rocks contain small amounts of ore minerals. The present author has made a study on the secondary alterations and reconstructed the succession of alteration processes to draw conclusions as to the physical and chemical conditions, and the course of these processes, suggesting hydrothermal, metasomatic origin of these alterations. Both secondary quartz and dickite are residual products that have originated due to hydrolysis of feldspars and removal of alkalis during hydrothermal processes. Silicification and dickitization preceded dolomitization. This is an evidence of a change in pH of solutions, from acid (pH about 4), to basic (pH about 9). Later, katagenetic processes were responsible for migration of substances and for repeated concentration of dickite in the form of veinlets.

 


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