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| Titel |
First physical volcanological description of a Miocene, silicic, phreatomagmatic fall complex in the Carpatho-Pannonian Region (CPR) |
| VerfasserIn |
Tamás Biró, Mátyás Hencz, Dávid Karátson, Emö Márton, Balázs Bradák-Hayashi, Zoltán Szalai |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142935
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| Publikation (Nr.) |
 EGU/EGU2017-6616.pdf |
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| Zusammenfassung |
| The study reports the basic physical volcanological and stratigraphical features of
a hitherto unrecognized silicic phreatomagmatic fall succession from the Bükk
Foreland Volcanic Area (Hungary), known as part of the extensive Miocene ignimbrite
volcanism of the northern CPR. The complex have been identified at two sites, in the
vicinity of Bogács and Tibolddaróc villages. Tens of mm to several dm thick layers
make up the 20 m thick entire succession. The complex could be subdivided into
three eruption cycles by two, intercalated well-developed paleosoil horizons, which
indicate longer repose periods. The eruption cycles consist of several individual
eruptive events. The volcano-sedimentological field approach was completed by
granulometrical and low field anisotropy of magnetic susceptibility (AMS) studies.
Combined dry sieving and laser diffraction particle size analysis were performed to
get information on median grain size (MdΦ) and sorting (σΦ) of friable layers.
AMS was used to infer the emplacement processes. Based on the following features
the succession is proposed to record a large-scale, silicic, phreatomagmatic fall
activity: i) Presence of very fine ash and abundant ash aggregates, ii) General poor
sorting, and often bimodal grain-size distributions; ii) Extremely weak magnetic
fabric compared to dilute, thin pyroclastic density current deposits. On the basis of
comparison of the recorded grain size characteristics with data from other silicic
phretomagmatic fall deposits worldwide, several units in the succession can be
considered as phreatoplinian fall deposit (sensu lato), described for the first time in the
CPR. |
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