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001-es BibID:BIBFORM080863
Első szerző:Karátson Dávid (földrajz-biológia tanár)
Cím:The latest explosive eruptions of Ciomadul (Csomád) volcano, East Carpathians : A tephrostratigraphic approach for the 51-29 ka BP time interval / D. Karátson, S. Wulf, D. Veres, E. K. Magyari, R. Gertisser, A. Timar-Gabor, Á. Novothny, T. Telbisz, Z. Szalai, V. Anechitei-Deacu, O. Appelt, M. Bormann, Cs. Jánosi, K. Hubay, F. Schäbitz
Dátum:2016
ISSN:0377-0273
Megjegyzések:The most recent, mainly explosive eruptions of Ciomadul, the youngest volcano in the Carpatho-Pannonian Region, have been constrained by detailed field volcanological studies, major element pumice glass geochemistry, luminescence and radiocarbon dating, and a critical evaluation of available geochronological data. These investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of Ciomadul's twin craters (St. Ana and Moho₀s) that received tephra deposition during the last eruptions of the volcano. Our analysis shows that significant explosive activity, collectively called EPPA (Early Phreatomagmatic and Plinian Activity), started at Ciomadul in or around the present-day Moho₀s, the older crater, at ?51 ka BP. These eruptions resulted in a thick succession of pyroclastic-fall deposits found in both proximal and medial/distal localities around the volcano, characterized by highly silicic (rhyolitic) glass chemical compositions (ca. 75.2?79.8 wt.% SiO2). The EPPA stage was terminated by a subplinian/plinian eruption at ?43 ka BP, producing pumiceous pyroclasticfall and -flow deposits of similar glass composition, probably from a "Proto-St. Ana" vent located at or around the younger crater hosting the present-day Lake St. Ana. After a quiescent period with a proposed lava dome growth in the St. Ana crater, a new explosive stage began, defined as MPA (Middle Plinian Activity). In particular, a significant two-phase eruption occurred at ~31.5 ka BP, producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of Sf. Ana, and followed by pumiceous fallout from a plinian eruption column. Related pyroclastic deposits show a characteristic, less evolved rhyolitic glass composition (ca. 70.2? 74.5 wt.% SiO2) and occur both in proximal and medial/distal localities up to 21 km from source. The MPA eruptions, that may have pre-shaped a crater similar to, but possibly smaller than, the present-day St. Ana crater, was followed by a so far unknown, but likewise violent last eruptive stage from the same vent, creating the final morphology of the crater. This stage, referred to as LSPA (Latest St. Ana Phreatomagmatic Activity), produced pyroclastic-fall deposits of more evolved rhyolitic glass composition (ca. 72.8?78.8 wt.% SiO2) compared to that of the previous MPA stage. According to radiocarbon age constraints on bulk sediment, charcoal and organic matter from lacustrine sediments recovered from both craters, the last of these phreatomagmatic eruptions ? that draped the landscape toward the east and southeast of the volcano ? occurred at ~29.6 ka BP, some 2000 years later than the previously suggested last eruption of Ciomadul.
Tárgyszavak:Természettudományok Földtudományok idegen nyelvű folyóiratközlemény külföldi lapban
Ciomadul
Tephrostratigraphy
Quaternary
Carpathians
Radiometric chronology
Megjelenés:Journal Of Volcanology And Geothermal Research. - 319 (2016), p. 29-51. -
További szerzők:Wulf, Sabine Veres Dániel Magyari Enikő (1973-) (biológus) Gertisser, R. Timar-Gabor A. Novothny, Á. Telbisz Tamás Szalai Zita Anechitei-Deacu, V. Appelt, O. Bormann, Marc Jánosi Csaba Hubay Katalin (1985-) (biológus, környezetkutató) Schäbitz, Frank
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