Petrography, geochemistry and petrology of the South Sahneh Ophiolite Complex (NE Kermanshah)

Abstract

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.

Keywords


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