Petrogenesis and Tectonic Setting Investigations of Ultramafic- mafic Rocks at the East of Fariman- Torbat- jam Lineament, NE of Iran

There are different interpretations on ultramafic rocks suite which are located at the North of Fariman- Torbat - Jam lineament, NE of Iran. Most authors interpreted these rocks as oceanic crust remnants wheras some authors believe that they are lavas with komatiitic to tholeiitic affinity. Obviously,These diffetent intetpretations have contrary geodynamic implications. Here, on the basis of incompatible trace rocks. Our observations including various immobile trace elements rations and position of rocks in (Nb/Th)N versus to (Nb/La)N, Nb/Th versus Zr/Nb diagrams indicating that they are not comparable to MORB like magmas. Moreover in a clear contrast to MORB most samples are plotted on or upper than Nb line in Zr/Y versus Nb/Y diagram, a geochemical feature that demonstrate their petrogenesis relation to the heterogeneous mantle plume source. The same inference may be bring up by spinels chemistry, as they have high and low contents of TiO2, Al2O3 respectively and set between spinels of plume related magma in the related diagrams. Key words: