US EPA

6875886 

Journal Article 

Mt. Nemrut volcano (Eastern Turkey): Temporal petrological evolution 

Cubukcu, HE; Ulusoy, I; Aydar, E; Ersoy, O; Sen, E; Gourgaud, A; Guillou, H; , 

2012 

1 

Journal of Volcanology and Geothermal Research
ISSN: 0377-0273 

ELSEVIER 

AMSTERDAM 

33-60 

10.1016/j.jvolgeores.2011.08.005 

WOS:000300530600004 

Quaternary active Nemrut volcano is situated 12 km north of the Bitlis-Zagros suture zone, southern margin of continental collision between Arabian and Anatolian plates. The latest activity of the volcano dates back to historic times. Volcanic evolution of the volcano is investigated under two main stages: Pre-caldera and post-caldera separated by paroxysmal caldera forming eruptions not older than 90 ka. The majority of the products are silica oversaturated peralkaline {([Na2O + K2O]/Al2O3) > 1} felsic rocks with rare transitional-to-mildly alkaline basalts and mugearites. A compositional gap (Daly Gap) between 53% and 59% SiO2 is partly filled with benmoreitic enclaves in peralkaline rhyolites. Benmoreitic enclaves display evidence of interminglement between mafic and felsic magmas. Observed mineral assemblages represent typical peralkaline mineralogy with aenigmatite, arfvedsonite-riebeckite, aegirine, fayalite and chevkinite. Geochemical evolution trends and modelling depict that protracted crystal fractionation dominated by feldspar, clinopyroxene, olivine and Fe-Ti oxides and crustal contamination would produce peralkaline rhyolites from the actual mafic compositions taken as parents. Mineralogical and petrographical observations indicate that the magma chamber is zoned compositionally having a crystal rich density layer between mafic and felsic melts. The genesis of Nemrut peralkaline magmatism has been ascribed to the ascension of slightly subduction modified asthenospheric melts into upper crustal high level reservoirs in localized extension in Mus ramp basin. (C) 2011 Elsevier B.V. All rights reserved.