Stratigraphy and age of the Cappadocia ignimbrites, Turkey: reconciling field constraints with paleontologic, radiochronologic, geochemical and paleomagnetic data

The issues faced in this study apply to other ignimbrite provinces in the world. For instance, ignimbrite eruption frequency in Cappadocia is higher than the resolution of many published K-Ar ages. Furthermore, different K-Ar ages have led to the description of individual and distinct ignimbrites that fieldwork and geochemical data allow to merge into a single ignimbrite. Argon loss from pumice samples leading to radiometric “rejuvenation” provides a likely explanation for most stratigraphic discrepancies. Cappadocia is the only documented ignimbrite field in which the chronostratigraphy of vertebrate remains provides better constraints on some ignimbrite ages than scattered K-Ar dates. We further argue that K-Ar dates from the Cappadocia area are too imprecise to establish a reliable magnetostratigraphic scheme for the ignimbrite succession, with the exception of the ∼2.8 Ma Valibaba Tepe ignimbrite.