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| Titel |
Violent Explosive Eruptions in the Ararat Valley, Armenia and Associated
Volcanic Hazards |
| VerfasserIn |
Khachatur Meliksetian, Ivan Savov, Charles Connor, Hripsime Gevorgyan, Laura Connor, Gevorg Navasardyan, Davit Manucharyan, Ruben Jrbashyan, Yura Ghukasyan |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121765
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| Publikation (Nr.) |
 EGU/EGU2016-608.pdf |
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| Zusammenfassung |
| The Anatolian-Armenian-Iranian volcanically active orogenic plateau is located in the
collision zone between the Arabian and Eurasian plates. The majority of regional geodynamic
and petrologic models of collision-related magmatism use the model proposed by Keskin
(2003), where volcanism is driven by Neo-Tethyan slab break-off, however an updated
model by Neill et al. (2015) and Skolbeltsyn et al.(2014) comprise break-off of two
slabs.
One of the significant (and understudied) features of the regionally extensive collision
zone volcanism is the diversity of eruption styles and also the presence of large number of
highly explosive (Plinian) eruptions with VEI≥5 during the Middle-Upper Pleistocene.
Geological records of the Ararat depression include several generations of thick low aspect
ratio Quaternary ignimbrites erupted from Aragats volcano, as well as up to 3 m thick ash and
pumice fall deposit from the Holocene-historically active Ararat volcano. The Ararat tephra
fall deposit is studied at 12 newly discovered outcrops covering an area ∼1000 km2. It is
noteworthy, that the Ararat tephra deposits are loose and unwelded and observed only in
cross-sections in small depressions or in areas where they were rapidly covered by younger,
colluvium deposits, presumably of Holocene age. Therefore, the spatial extent of the
explosive deposits of Ararat is much bigger but not well preserved due to rapid
erosion.
Whole rock elemental, isotope (Sr, Nd) and mineral chemistry data demonstrate
significant difference in the magma sources of the large Aragats and Ararat stratovolcanoes.
Lavas and pyroclastic products of Aragats are high K calc-alkaline, and nearly always
deprived from H2O rich phases such as amphibole. In contrasts lavas and pyroclastic
products from Ararat are medium K calc-alkaline and volatile-rich (>4.6 wt% H2O and
amphibole bearing) magmas. Here we shall attempt to reveal possible geochemical triggers of
explosive eruptions in these volcanoes and assess volcanic hazards for the region of Ararat
valley based on numerical simulations. Our work is important as Ararat Valley host the
capital city of Yerevan (population ∼ 1.4 million) and also the currently operating Armenian
Nuclear Power Plant at Metsamor.
References
Keskin,2003. GRL 30, 1–4; Neill et al., 2015 Chemical Geology, 403, p. 24-41;
Skolbeltsyn et al. 2014. Tectonics 33, 207–221. |
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