Geochemistry and tectonic setting of Maien Bolagh (Takab) alkali gabbros-NW Iran

Abstract

Some small gabbro patches emplaced along the thrust fault with W-E trend in the vicinity of Maien Bolagh village at the HT/MP metapelites, a part of the Central Iran zone (near to Sanandaj-Sirjan zone). The coarse-grained dark gabbro samples consist of amphibole, clinopyroxene, plagioclase, minor quartz, titanite, and biotite. Gabbros have high potassic calc-alkaline to shoshonitic affinity. The highly incompatible elements concentrations (e.g. Nb and La) and Zr/Y and Zr/Nb ratios are similar to within plate gabbros. At the assorted discrimination diagrams the gabbros exhibit mostly non-orogenic resemblance. The geochemical characteristics show that the gabrros can be interpreted as melts formed from an enriched mantle in a passive rift position, during an extensional or transtensional tectonic

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