The Occurrence of Vitric Tuff in Quaternary Deposits of Gljev in Dalmatia (Southern Croatia)

For the first time in the Dinaric region of Dalmatia vitric tuff has been discovered in the clayey Quaternary deposits. Petrographic, heavy mineral and X-ray analyses revealed fine volcanic ash, illitic material (as an alteration product of glass shards), rare feldspar grains and an abundance of monoclinic pyroxene in the heavy mineral fraction. Pyroclastic quartz grains were not observed. It is postulated that explosive volcanism of basic or neutro-basic character occured and the finest particles were transported over a large distance by wind. From the heavy mineral composition the investigated tuff differs from the underlying and overlying Quaternary clay sediments, as well as from the tuffs found in Neogene deposits of Central Dalmatia.