REE distribution in tertiary and quaternary volcanic rocks from central and western Anatolia

Elemental abundances of the Rare Earth Elements (REE) La, Ce, Nd, Sm, Eu, Tb, Yb, Lu have been determined by INAA in four Quaternary calc- alkaline volcanic rocks coming from Erciyes Dag (Central Anatolia), in six high- K calc-alkaline rocks, three shoshonites and two alkaline basalts coming from the Oligocene- Miocene volcanic series of western Anatolia. The calc-alkaline rocks show fractionated light REE patterns and unfractionated ·heavy REE patterns. The high-K calc- alkaline and shoshonitic rocks have higher overall abundance of REE in respect to the calc-alkaline samples and show fractionation for both light and heavy REE. The increase of absolute abundance of REE from typical calc- alkaline through high- K calc- alkaline to shoshonitic rocks accompanied •by an increase of fractionation in the heavy REE suggests a source region for both calc- alkaline and K- enriched magmas within an anomalous upper mantle enriched in REE. The observed differences in the LREE, light and heavy REE fractionation can be explained by differences in the degree of melting and by differences in the type of the residual phases in equilibrium with calc- alkaline, high- K calc-alkaline and shoshonitic magmas during the partial melting within the upper mantle.