etrology and geochemistray of Imam-Zadeh Hashem mafic and ultramafic bodies, southern Guilan province

Mafic and ultramafic plutonic igneous bodies، with small and big outcrops، between Shemshak rock units (Jurassic) are observed in east of Imam Zadeh Hashem، in southern Guilan province. Ultramafic cumulates consist of clinopyroxenite، and plagiofer clinopyroxenite، olivine clinopyroxenite، and mafic rocks، based on mineralogy consist of gabbros، olivine gabbros، biotite gabbros and amphibole gabbros. According to geochemical data، studied rocks have tholeiitic nature and in the tectonic setting diagrams، display arc characteristic. The chondrite normalized REE patterns show low enrichment in LREEs relative to HREEs. The negative Nb and Ti anomalies in primitive mantle and MORB-normalized multi-element diagrams of the rocks are characteristic of island arc magmas. Also، enrichment in LILE and depletion of HFSE may indicate a subduction-related tectonic setting. According to geological and geochemical evidence، Imam-Zadeh Hashem ultramafic and sub-alkaline gabbro rocks can be as a part of the Southern Caspian Sea Ophiolite sequence (SCO) that formed in a suprasubduction tectonic system.