سنگنگاری، ژئوشیمی و سنگشناسی مجموعه افیولیتی جنوب صحنه )شمال شرق کرمانشاه(

Ophiolitic complex of Sahneh could be considered as part of ophiolite sequences in the Zagros Suture Zone.This complex is a part of 3000 km belt, which is started from Syria after crossing south Turkey and Zagros leading to Oman. The studied ophiolitic complex is curvature in shape which is situated in south of Sahneh. No complete ophiolite sequence were seen in this complex. In general, the present lithology of the area consists of harzburgitic peridotites, isotrope and mylonitic gabbros, and small outcrop of plagiogranite sequence. Ultramafic rocks consist mainly of harzburgite, dunite, lherzolite, websterite, and mafic rocks are composed of pegmatoidic gabbro, olivine gabbro, mylonitic gabbros and isotrope gabbros. On the bases of major elements diagrams and spider diagrams, this complex could be resulted from a P-type ocean floor tholeiitic basalt (P or E MORB). Geochemical and petrological evidence showed that parent magma were high Mg sub-alkaline in type. Tholeiitic nature of magma are responsible for the formation of oceanic crust, and their position on to the mid oceanic ridge field. The P-type nature of magma indicated that the old-ridge were formed during a high spreading sea floor conditions. Geochemical and petrological evidence showing that parent magma were picritic in composition and may resulted from high melting ratio of the upper mantle.