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Aus ungarischer Sicht

A Middle Miocene, ~8 m thick pyroclastic succession, reported from the Bükk Foreland Volcanic Area (BFVA) in Northern Hungary (Central Europe) specified here as the Jató Member, was produced by silicic phreatomagmatism (Phreatoplinian sensu lato). Two well-preserved outcrops ~8 km apart and inferred to be within ~10–50 km from source represent the discontinuously exposed, layered, paleosol-bounded, phreatomagmatic JatóMember. They show an identical phenocrystal assemblage of feldspar, biotite and amphibole without weathered zones or signs of erosion, that suggest deposition in one eruption phase lasting hours to months. The succession contains three subunits: 1) subunit A, 1.8 m thick, a series of well-sorted fine to coarse ash or lapilli tuff layers with constant thickness; 2) subunit B, 2.1 m thick, a series of normal-graded layers with an upper fine-grained zone containing abundant ash aggregates with a coarser-grained core and distinctively finer-grained outer rim; 3) subunit C, 4.5 m thick, a massive, poorly to well-sorted coarse ash with gas escape structures and ash aggregates at its base. The upward change of these lithofacies implies an initially sustained dry fallout-dominated deposition of ash and pumice lapilli resulting in subunit A. Subsequently, multiple wet and dilute Pyroclastic Density Currents (PDCs) dispersed subunits B and C. The general abundance of PDC-related ash aggregates in the middle-upper part of the succession (particularly in subunit B), and the transformation of a fall-dominated to a collapsing depositional regime producing wet dilute PDCs, imply the increasing influence of water during the eruption (Phreatoplinian sensu lato). The presence of water is related to an epicontinental sea duringMiddle to LateMiocene in the Carpatho-Pannonian region. The transition from an initial dry magmatic phase generated fallout activity followed by the emplacement of wet PDCs' rich in ash aggregates, when external water infiltrated from a surrounding lake or sea water entered the vent. ; ÚNKP-16-3 New National Excellence Program of the Ministry of Human Capacities and the National Talent Program – Young Talents of the Nation (NTPNFTÖ- 18-B-0130). Thisworkwas supported by theHungarian Scientific Research Fund project nos. K105245, K115472, K128625, K131894, K128122 and by the European Union and the State of Hungary, cofinanced by the European Regional Development Fund in the project of GINOP - 2.3.2 - 15 - 2016 - 00009 ICER. KN's contribution and field work were possible by the fund available under the Erasmus+ International Credit Mobility, - ELTE –Massey University Research Cooperation Program. Balázs Bradák acknowledges the financial support of project BU235P18 (Junta de Castilla y León, Spain) and the European Regional Development Fund (ERD).