Textural records and geochemistry of the Kermanshah mantle peridotites (Iran): implications for the tectonic evolution of southern Neo-Tethys

Kermanshah Ophiolite Complex (NW Iran), located along the Main Zagros Thrust Zone, marks the ophiolitic suture between the Arabian and Sanandaj-Sirjan continental blocks. N-MORB-normalized multielement patterns and chondrite--normalized REE patterns in the Kermanshah mantle restites show depletion i...

Full description

Saved in:
Bibliographic Details
Published in:Journal of geosciences (Prague) 2017-01, Vol.62 (3), p.165-186
Main Authors: Moradpour, A., Zarei Sahamieh, R., Ahmadi Khalaji, A., Sarikhani, R.
Format: Article
Language:English
Subjects:
Aluminum oxide
Decompression
Geochemistry
Geology
Magma
Mantle
Melts
Mineralogy
Modelling
Olivine
Ophiolites
Paleoceanography
Peridotite
Petrogenesis
Petrology
Plate tectonics
Ratios
Rock
Rocks
Spinel
Stratigraphy
Subduction
Subduction (geology)
Subduction zones
Titanium dioxide
Transition zone
Ultramafic rocks
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Kermanshah Ophiolite Complex (NW Iran), located along the Main Zagros Thrust Zone, marks the ophiolitic suture between the Arabian and Sanandaj-Sirjan continental blocks. N-MORB-normalized multielement patterns and chondrite--normalized REE patterns in the Kermanshah mantle restites show depletion in incompatible elements concentrations with respect to the depleted MORB mantle (DMM). In the V vs. Yb diagram, Harsin-Sahneh-Norabad and Miyanrahan peridotites (Kermanshah Ophiolite Complex), due to their relatively low V contents, fall close to the QFM buffer. Calculated TiO2 and Al2O3 compositions in the parental melt that were in equilibrium with chromian spinel are consistent with supra-subduction zone-type compositions. Besides, calculated FeO/MgO ratios in the parental melts are comparable with those in boninites from Oman ophiolites. Olivine from the peridotite restites is highly magnesian (Fo89-93) with NiO contents of 0.2-0.4 wt. %, consistent with formation in a forearc environment. This is also proven by the Cr# and Mg# values as well as TiO2, Cr2O3, and Al2O3 concentrations in chromian spinel of ultramafic rocks. Accordingly, petrogenetic modeling indicates that the Kermanshah ultramafic rocks may represent the residual mantle after extraction of 13-23% of boninitic-type melts. Decompression, melting and melt-rock reaction related textures are widespread in the Kermanshah mantle restites. Field relationships and geochemical evidence reveal that the studied ophiolites were a part of a rifted basin at the ocean-continent transition zone formed in the south Neo-Tethyan Ocean.
ISSN:1802-6222
1803-1943
DOI:10.3190/jgeosci.244