New insights into the ultrapotassic magmatism through xenoliths from the Eğirdir area, West Anatolia, Turkey

Plutonic xenoliths have been found within a pipe and a related phreatomagmatic leucitite deposit in the Eğirdir lake area, belonging to the Potassic-Ultrapotassic Afyon volcanic Province, West Anatolia. They consist of kamafugite-type, feldspar-bearing syenite, pyroxenite, leucitolite, some small-sized melilitolite and garnet-rich xenoliths, and a carbonatite. A new occurrence of kalsilite is described as either homogeneous acicular crystals or tabular two phases-exsolved crystals in the kamafugite-type and melilitolite xenoliths. Rock textures and compositions indicate cumulates and near-liquid composition rocks corresponding to relatively evolved magmas. All the rocks are strongly silica-undersaturated, Ca-, Mg-, and K-rich, and Al-poor. The fractional crystallization model includes clinopyroxene, apatite, phlogopite, melilite and leucite. Fe-Ti oxides and garnet may be also concerned. The P H2O during crystallization and differentiation is not more than 0.8 GPa. Major elements, trace elements, and REE patterns for xenoliths, which indicate near-liquid compositions, are typical of ultrapotassic series in a post-collisional geodynamic context, as it is the case for the Roman and Central ultrapotassic Italian provinces. The stable isotope 13 C and 18 O values of the calcio-carbonatite plot close to the primary carbonatite field, whereas the carbonates of the feldspar-bearing syenite and the peperite matrix suggest a low-T extensive contamination process. The origin of the carbonatite from kamafugite-type magmas by immiscibility or by fractional crystallization remains questionable; an origin by fractionation-melting of a metasomatized mantle source should be tested in the future.