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 (Ar-40/Ar-39 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 Ar-40/Ar-39 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.