During Earth's history, geosphere-biosphere interactions were often determined by
momentary, catastrophic changes such as large explosive volcanic eruptions. The Miocene
ignimbrite flare-up in the Pannonian Basin, which is located along a complex convergent
plate boundary between Europe and Africa, provides a superb example of this interaction.
In North Hungary, the famous Ipolytarnoc Fossil Site, often referred to as "ancient
Pompeii", records a snapshot of rich Early Miocene life buried under thick ignimbrite
cover. Here, we use a multi-technique approach to constrain the successive phases
of a catastrophic silicic eruption (VEI >= 7) dated at 17.2 Ma. An event-scale reconstruction
shows that the initial PDC phase was phreatomagmatic, affecting >= 1500 km(2) and
causing the destruction of an interfingering terrestrial-intertidal environment at
Ipolytarnoc. This was followed by pumice fall, and finally the emplacement of up to
40 m-thick ignimbrite that completely buried the site. However, unlike the seemingly
similar AD 79 Vesuvius eruption that buried Pompeii by hot pyroclastic density currents,
the presence of fallen but uncharred tree trunks, branches, and intact leaves in the
basal pyroclastic deposits at Ipolytarnoc as well as rock paleomagnetic properties
indicate a low-temperature pyroclastic event, that superbly preserved the coastal
habitat, including unique fossil tracks.
