Geochemistry of basaltic rocks of Meshkin- Rasht Abad area (North of Zanjan)

The Meshkin-Rasht Abad area is a small part of the western Alborz-Azarbaijan magmatic belt (AAMB). Field investigations reveal that andesitic-basalt rocks are the dominant rock units of the area with high-K calc-alkaline to shoshonitic affinities. On the basis of geochemical features all rocks are enriched in light rare earth elements (LREE), large ion lithophile elements (LILE) and have positive anomalies of Pb, U and Cs and Ti, Sr and Nb negative anomalies. These volcanic rocks have the criteria of active continental margin arcs on tectonomagmatic discrimination diagrams. Geochemical data, including low amounts of Cr, Ni, V, and Zr/Nb ratio suggest the enriched mantle source (lithospheric mantle) for the rocks under study. Moreover, the diagrams of the ratio of highly incompatible elements indicate the effect of slab-derived fluids on the magma generation. The Ce/Pb low value as well as various geochemical diagrams demonstrate that the magma is possibly contaminated by continental derived-crustal materials.