The Tudeshk area in southeastern part of Nain, Central Iran is located in Urmiyeh- Dokhtar magmatic belt and is a part of Kajan 1:100000 map of GSI.  The stratigraphic sequence is composed of Mesozoic and Cenozoic strata, consisting of Cretaceous limestone, Tertiary volcanic rocks (Lavas and pyroclastics) and also Quaternary deposits.
     The Neogene section is indicated by Upper Red Formation (URF), and a dacitic (Ng ^d), unit. The rock type variations in Neogene volcanics along with the geochemical and petrographic evidences indicate a kind of sodic character. Mixing and fractional crystallization in magmas, are important, phenomena which has been resulted in this study.
    Along with the above processes, the associated basic rocks have been strongly altered, caused by fluid pressures, high temperatures and the nature of late fumarolic fluids. This area has been subjected to a fault and fracture system with a NW-SW trend, indicates that the area has passed a brittle type tectonic regime, which follows the main trend of Urmiyeh-Dokhtar magmatic belt. This kind of extensional tectonic regime controlled the emplacement of igneous rocks The geochemical characteristics of basalts in Tudashak area (drown as spider diagrams in special cases) has been compared with the basaltic rock-types in other places of the world as: Parana (South America), Rio Grande (North America), Deccan (India) and Ethiopia. All of analysis results plot in subalkaline field of diagram, indicating contamination with amphibolitic gneisses of sialic crust during the initial stages of ascending. similarity with the Tudashak Neogene basalts show a considerable similarity with the Rio Grande Basalts and form this point of view. It could be deduced that the partial melting of a depleted mantle is responsible for the formation of these basalts, and has a similarity to the steans Basalts of North America Basin and Range