GEOCHEMICAL CHARACTERISTICS OF THE LAVA DOMES IN YATAGAN VILLAGE AND SAĞLIK TOWN, FROM ERENLERDAGI (KONYA, CENTRAL TURKEY) VOLCANITES

Extensive Late Miocene to Pliocene Erenlerdagi volcanism produced lava domes, nue´e ardentes and ignimbrite deposits in west and southwest of the Konya. The domes may contain various enclaves, which range in size from a few cm to a few meters, and in shape cornered to spherical. The volcanic rocks are made up of plagioclase (15-45%), brown amphibole (3-15%), brown biotite (5-10 %), quartz (0-5%), sanidine (0-5%), clinopyroxene (0-5 %), epidote (0-8%), opaque iron ore (3-20%), and accessory acicular apatite and zircon in a holocrystalline porphyric texture. Geochemical data shows that all samples are high-K calc-alkaline, mostly metaluminous, and rhyodacite to andesite in composition. They are characterized by an enrichment in Large Ion lithophile Elements (e.g. Cs, K), and a depletion in High Field Strength Elements (e.g. Ti, Y). In Harker variation diagrams, SiO2 increases with increasing K2O, Na2O, Rb, Th, U, Nb, Zr contents; and decreasing TiO2, FeOt, MgO, CaO contents, suggesting fractional crystallisation of hornblende (± pyroxene, olivine) and titanite. The REE pattern of the samples shows an enrichment in Light Rare Earth Elements, and a depletion in Heavy Rare Earth Elements, resultant with high [(La/Lu)N= 8.2-18.0] ratios. Existence of slight Eu anomaly (Eu/Eu*: 0.66-0.80 ) may suggest plagioclase fractionation in the samples. Based on field, mineralogical and geochemical data, it has been suggested that the Erenlerdagı volcanics could have formed by chemical mixing of felsic and mafic magmas possibly coupled with fractional crystallisation of hornblende (± pyroxene, olivine), plagioclase and titanite, in relation with the subduction of the African plate underneath the Anatolian plate during Miocene.