Abstarct: The present study focused on the basaltic lava flows from the Oligo-Miocene siliciclastic-evaporites sedimentary succession which coverd large parts of the northern edge of Central Iran, about 300 kilometers long from Sabzevar to Shahroud. These lava flows along with pyroclastic units observed as interbeded with the Oligo-Miocene sedimentary units. Previous researchers assigned these lava flows to Quaternary But the study of exact stratigraphic evidence of this area show Oligocene-Miocene age for them. These basaltic rocks (with olivine basalt to basalt in composition) show porphyritic, glomeroporphyritic and trachytic textures and composed of olivine, clinopyroxene and plagioclase phenocrysts in a glassy to microlitic ground mass. baxsed on mineral chemistry, pyroxene, plagioclase and olivine compositions are diopside to augite with (Wo40.46-50.76 En34.99-50.68 Fs5.85-16.42), andesine to bytownite (An23–An73) and hyalosiderite to forsterite (Fo68 – Fo91),respectively.The results of clinopyroxene thermobarometry shows that basalt-hosted clinopyroxene crystallized at pressures range from 2 to 10 kbar with the average of 8 kbar and temperatures range from 1100 to 1280ºC, corresponding to the middle crust (ca. 20 Km). While olivine– thermometry yields a temperature range from 1200 –1300 ℃. baxsed on the combination of clinopyroxene, primary magma of basalts have alkaline nature. The rocks display initial 87Sr/86Sr and 143Nd/144Nd ratios of 0.7037 to 0.7039 and 0.512770 to 0.0512841, respectively. These initial ratios indicate a mantle source with slight crust contamination. On the basis of geochemical data, the parental magma of these rocks has sodic- alkaline affinity, enriched in LILEs and LREEs and depleted in HREEs, with negative anomalies in HFSEs. The basalts show the geochemical characteristics of the basaltic magmas originated from partial melting of adjusted enriched garnet lherzolite mantle source beneath the continental areas of extensional back-arc basins.On the basis of geochemical data, the parental magma of these rocks has sodic- alkaline affinity, enriched in LILEs and LREEs and depleted in HREEs, with negative anomalies in HFSEs. The basalts show the geochemical characteristics of the basaltic magmas originated from partial melting of adjusted enriched garnet lherzolite mantle source beneath the continental areas of extensional back-arc basins. Geochemical studies show magma forming of these rocks have been formed from 1- 10% partial melting of an enriched modified garnet lherzolitic mantle source in 90-100 km depths and reflect role of fractional crystallization as the main process in magma evolution. In addition to the Oligo-Miocene basalts, the Jurassic basic magmatism in the study area is seen as dyke in Reza abad. Magma forming of these rocks have calc – alkaline nature and enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and also depleted in heavy rare earth elements (HREE). The mentioned magmas, originated from 5 to 30% partial melting of the spinel peridotitic (below the central Iran) and garnet lherzolithic (below the Eastern Alborz) mantle plumes in an immature extensional back arc basin tectonic setting due to oblique subduction of neothetyan oceanic lithosphere beneath the central Iran structural zone at late Triassic to middle Jurassic time, and were ascending to upper levels of continental crust by fault and fracture systems and emplaced in shallow sedimentary basins of these zones in different ways. This basin formed in the behind of the upper Triassic – Lower Jurassic magmatic arc of central Iran and due to initiation of extensional movements in the continental crust of central Iran and Alborz. Thermobarometry of diabaxse dyke determines a temperature of 1100-1200 °C and pressures 1 – 10 Kbar with a density in 4-8 Kbar.