Hencz, Mátyás, Biró, Tamás, Németh, Károly, Szakács, Alexandru, Portnyagin, Maxim , Cseri, Zoltán, Pécskay, Zoltán, Szabó, Csaba, Müller, Samuel and Karátson, Dávid (2024) Lithostratigraphy of the ignimbrite-dominated Miocene Bükk Foreland Volcanic Area (Central Europe). Journal of Volcanology and Geothermal Research, 445 . Art.Nr. 107960. DOI 10.1016/j.jvolgeores.2023.107960.

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Abstract

Highlights

• An event-scale, complete lithostratigraphic column for the Miocene BFVA was created through extensive field volcanology.
• Field volcanology was supplemented by volcanic glass geochemistry to separate the eruptions.
• An example is presented how to undertake lithostratigraphy-based classification in poorly preserved, deeply eroded volcanic terrains.
• In the ancient BFVA landscape, sea cover during eruptions and terrestrial deposition is evident.

Abstract

This study documents the volcanic evolution of the Miocene silicic Bükk Foreland Volcanic Area (BFVA), Northern Hungary (Central Europe) at an event-scale. The BFVA is a deeply eroded and dissected volcanic field dominated by multiple, several 10-m thick, valley-filling silicic ignimbrite units, which are chemically and texturally very similar to each other. Hence, establishing lateral correlation is a real challenge due to the sporadic and small-scale outcrops and lack of stratotypes. Detailed field observations allowed us to identify eleven lithological members including fourteen eruption events and establish a nearly complete lithostratigraphic correlation between fifteen outcrops across the BFVA. Primary pyroclastic material of each member was sampled, and volcanic glass was geochemically analyzed for major and trace element composition. The geochemical results confirm the field-based classification of the members and enable the correlation of distinct outcrops. The major and trace element composition of the glassy pyroclasts of each member of the BFVA served as basis to create a field-wide chemical reference database for regional correlational studies. Here, a new lithostratigraphic classification scheme (consisting of one lithostratigraphic formation and eleven members) is presented, which reflects the challenges unraveling the stratigraphy of ancient volcanic terrains. The field-based event-scale lithostratigraphy of the BFVA suggests a wet, partly sea-covered depositional environment in the close vicinity of the eruption centers providing favorable conditions to ‘fuel’ silicic explosive phreatomagmatism. On the contrary, paleosol horizons formed after almost each major eruption event or sequence suggests an overall near-coast terrestrial environment for the BFVA, where the emplacement of the pyroclastic material occurred.

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