engleski

An occurence of Badenian rhyolitic volcanoclastic rocks from middle parts of Mt. Dilj (Eastern Croatia)

A polyphase volcanism which took place during the Badennian in the area of the present Mt. Dilj as well as in surrounding Slavonija had given rise to changes in palaeoecological environment and thus essentialy contolled the growth of biolithite bodies. During the comparatively calm interval of sedimentation, carbonate rocks with corals as reef-forming elements under very favourable environment were deposited. By contrast, the growth of reef is ceased by intermittent volcanic phases which give rise to the influx of pyroclastic material. A bed of slightly consolidated monomictic gravel in the lower parts of the lithostratigraphic column Zdenci has been studied in detail. All analysed fragments of gravel and insoluble residium of bioclastic limestone have rhyolitic composition. Rhyolitic verietes as follows have been determined: crystallovitrophyric and vitrocrystal rhyolitic tuff, spherulitic rhyolite, aphyric alkali-feldspar rhyolite and slightly porphyritic alkali-feldspar rhyolite.

Badenian; bioclastic limestone; volcanism; alkali-feldspar; rhyolite; rhyolitic tuff

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