Modern analogues for Miocene to Pleistocene alkali basaltic phreatomagmatic fields
in the Pannonian Basin: "Soft-substrate" to "combined" aquifer controlled phreatomagmatism
in intraplate volcanic fields
The Pannonian Basin (Central Europe) hosts numerous alkali basaltic volcanic fields
in an area similar to 200 000 km2. These volcanic fields were formed in
an approximate time span of 8 million years producing smallvolume volcanoes typically
considered to be monogenetic. Polycyclic monogenetic volcanic complexes are also common
in each field however. The original morphology of volcanic landforms, especially phreatomagmatic
volcanoes, is commonly modified. by erosion, commonly aided by tectonic uplift. The
phreatomagmatic volcanoes eroded to the level of their sub-surface architecture expose
crater to conduit filling as well as diatreme facies of pyroclastic rock assemblages.
Uncertainties due to the strong erosion influenced by tectonic uplifts, fast and broad
climatic changes, vegetation cover variations, and rapidly changing fluvio-lacustrine
events in the past 8 million years in the Pannonian Basin have created a need to reconstruct
and visualise the paleoenvironment into which the monogenetic volcanoes erupted. Here
phreatomagmatic volcanic fields of the Miocene to Pleistocene western Hungarian alkali
basaltic province have been selected and compared with modern phreatomagmatic fields.
It has been concluded that the Auckland Volcanic Field (AVF) in New Zealand could
be viewed as a prime modern analogue for the western Hungarian phreatomagmatic fields
by sharing similarities in their pyroclastic successions textures such as pyroclast
morphology, type, juvenile particle ratio to accidental lithics. Beside the AVF two
other, morphologically more modified volcanic fields (Pali Aike, Argentina and Jeju,
Korea) show similar features to the western Hungarian examples, highlighting issues
such as preservation potential of pyroclastic successions of phreatomagmatic volcanoes.