Petrogenetic study of Quaternary basaltic rocks from Azerbaijan, NW Iran

The study area is located in northwest of Iran، in the western Alborz-Azerbaijan structural zone. Based on petrography and geochemical studies، the Quaternary basic volcanic rocks of the study area have alkali-olivine basalt and trachy basalt composition and alkalinesubalkaline nature. According to tectonic diagrams، the samples are plotted within-plate continental basalts field. The Quaternary volcanic centers are situated within pull-apart basin structures and are controlled by active faults. The average Ce/Pb and Nb/U ratios of the studied basalts are lower than the value، for average oceanic basalts (OIB and MORB). These ratios are close to the average values of sub-continental lithospheric mantle. According to geochemical characteristics of trace elements and REE patterns، all the analyzed basalt samples have LREE enrichment chondrite-normalized REE patterns، suggesting that they may have been generated by different partial melting degrees (Ahar 3-4%، Maku 1 - 15% and Sarab 5-15%) of a sub-continemtal lithospheric mantle source.