In western part of the CEIM (Central-East Iranian Microcontinent) (Bayazeh area, Isfahan province, Iran), a series of Paleozoic basaltic rocks, occur. Major minerals of these basalts are olivine, clinopyroxene (diopside, augite), plagioclase (albite), sanidine, amphibole (kaersutite), phlogopite, ilmenite and magnetite. Secondary minerals include epidote, pumpellyite, albite, calcite and chlorite. Olivine and clinopyroxene are as phenocryst, while feldspars are restricted to groundmass. Chemical composition of clinopyroxenes indicates crystallization during ascending of magma. Geochemical analysis of whole rock samples shows that these rocks are characterized by low SiO2 (43.21-48.45 wt %), high TiO2 (1.81-3.00 wt %) and P2O5 (0.18-0.34 wt %). Petrography, chemistry of clinopyroxenes and whole rock analyses reveal an alkaline nature of these basalts. They are enriched in alkalis (Na2O + K2O = 4.1-7.7 wt %), LILE, HFSE and LREE. The Bayazeh alkali-basalts present strong enrichment in LREE relative to HREE (La/Lu ratio = 77.6-119.6) and were dominantly derived from partial melting of a metasomatized asthenospheric garnet-amphibole lherzolite. Field relationships reveal that junction of faults in west of the Bayazeh prepared a suitable path for ascending of magma from deep regions to surface and intra-plate continental magmatism. The Paleo-Tethys subduction from lower to upper Paleozoic is too enough for mantle enrichment in volatiles and basaltic alkaline magmatisrn in upper Paleozoic of Bayazeh area. © 2011 Pleiades Publishing, Ltd.