Acigöl rhyolite field, central Anatolia (part II): geochemical and isotopic (Sr–Nd–Pb, [delta]18O) constraints on volcanism involving two high-silica rhyolite suites - Siebel, Wolfgang; Schmitt, Axel Karl; Danišik, Martin; Aydin, Faruk (Contributions to mineralogy and petrology, 2011)