Tufy i otoczaki skał wylewnych w profilu górnego karbonu okolic Świerzawy
Abstract
Tuffs and eruptive rock pebbles in the Upper Carboniferous near Świerzawa
Abstract
In the profile of the series previously regarded as the Middle or Lower Rotliegende, recently referred to the Westphalian and Stephanian, tuffs and tuffites, also pebbles of eruptive rocks, occur among clastic deposits. This indicates the continuation of volcanic activities throughout the sedimentation of the above series, contrary to the currently held views that they started after the termination of the sedimentation. A short microscopic description is given here of the character of the tuffs and tuffites, also of thin sections of the pebbles from eruptive rocks. It has been observed that the composition of the tuffs corresponds to eruptions of an acid nature, while the eruptives which were the parents rocks of pebbles did not contain quartz phenocrysts. These pebbles had been transported from only one (poor lithological differentiation) and rather distant source (good roundnes). In the writer's opinion the tuffs represent the primary preliminary phases of eruption in the vicinity of Świerzawa while the pebbles have been brought from source areas.