Correlation of ignimbrites in the central Anatolian volcanic province using zircon and plagioclase ages and zircon compositions

Episodes of high eruptive fluxes (>10(-3) km(3)/year) in continental environments are associated with magmatism related to subduction, post-orogenic collapse, intra-plate hot spots, or rifting. During such episodes, voluminous ignimbrite deposits are produced which cover landscapes over 10(4)-10(5) km(2). In such sequences, brief eruptive recurrence and chemical similarity limit the applicability of geochronological and geochemical correlation methods. Here, we present complementary geochronological data (40Ar/39Ar plagioclase eruption and Pb-206/U-238 zircon crystallization ages) for ignimbrites from the Miocene-Holocene Central Anatolian Volcanic Province (CAVP). In addition, we successfully employed zircon geochemistry (trace elements, oxygen isotopes) as an alteration-resistant indicator to correlate rhyodacitic to rhyolitic ignimbrites whose eruption age differences are too brief to be resolved by 40Ar/39Ar geochronology. By applying this method, we dismiss previous correlations between stratigraphic members (i.e., Sofular and Gordeles, Sofular and Sanmadentepe), but demonstrate close relationships for other CAVP ignimbrites (i.e., Kayak units 1 to 4; Cemilkoy ignimbrite and overlying fallout deposits). Our chronostratigraphy reveals two previously unrecognized eruptive pulses at -9-8 Ma and 7-5 Ma which are characterized by increasing magmatic temperatures (-75-100 degrees C within each cycle). Despite a long-term (10 Ma) eruptive productivity that is about one order of magnitude smaller than in other magmatically active continental plateaus, the CAVP achieved high eruptive fluxes during brief (1-2 Ma) intervals. (C) 2011 Elsevier B.V. All rights reserved.