Neogene volcanic rocks and granitoid plutons are among the most important geological components of western Turkey. Although they are voluminous north of the Gediz Graben, they are very scarce to the south, where volcanic rocks occur as isolated small exposures in a small number of localities. The Kiraz Basin of the Kucuk Menderes Graben is a key locality, in which Tertiary volcanic rocks crop out at three locations. These rocks have been chemically analysed and dated (Ar-39-Ar-40 whole rock and biotite analyses) in order to understand their tectonic setting of emplacement and its relation to the wider structure of western Anatolia. Whole rock and biotite Ar-39-Ar-40 ages vary between 13.9 +/- 0.2 Ma and 14.6 +/- 0.2 Ma.