Early Miocene pyroclastic rocks of the Bükkalja lgnimbrite Field (North Hungary) - A preliminary stratigraphic report

Abstract

This preliminary report provides a detailed description of several stratigraphie sequenees of the Early Miocene Bükkalja Ignimbrite Field, summarizing the main volcanosedimentological eharacters. Many volcanological features suggest that most of the deposits can be classified as high volume pyroclastie flows (ignimbrite). Two major ignimbritie units have been distinguished, which may belong to two different stages of the vo1canism and form a SW-NE orientated belt. The first (lower) unit is eharaeterized predominantly by non-welded ignimbrites, whereas the second (upper) unit, usually found south of the first unit, shows variable degrees of welding. Hydrovolcanic deposits also occur in different stratigraphie horizons. The final phases of volcanism could have been contemporancous with lacustrine sedimentation