WULKANOKLASTY DOLNOKARBOŃSKICH FORMACJI SKALNYCH POMORZA ZACHODNIEGO

Abstract

VOLCANICLASTS OF LOWER CARBONIFEROUS ROCK FORMATIONS IN WESTERN POMERANIA

Abstract. Lower Carboniferous rocks of Western Pomerania are interesting in terms of petrographic composition containing fragments of volcanic rock (called volcaniclasts). This unique volcanic material is abundant in Lower Carboniferous sandstones. However, the volcanic clasts are present in all types of Lower Carboniferous sedimentary rocks of this zone. The paper presents an attempt of classification of clasts in volcanic rocks from the Koszalin-Chojnice zone. The volcaniclasts are divided into three main groups. Clasts were divided mainly according to their structural features. Some clasts have been indentified as parts of holocrystalline - felsitic rocks with the attributes of granophyric, poikilitic and spherolitic structures, and as grains of semi-crystalline rock structures with dendritic development. There are also some clasts showing different structural types combined. Parent rocks for the volcaniclasts were acidic igneous rocks from the quartz porphyry and quartz-free porphyry group (rhyolite-dacite series).