Petrology
Shirin Behpour; Abbas Moradian; Hamid Ahmadipour
Abstract
The studied area is located in the SE of Bam and Urumieh-Dokhtar Magmatic Arc. Based on petrographical and geochemical characteristics, studied rocks contain tonalite, granodiorite, granite and alkali granite. These rocks are metaluminous, weakly peraluminous, high-K, and calc-alkaline. The behavior ...
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The studied area is located in the SE of Bam and Urumieh-Dokhtar Magmatic Arc. Based on petrographical and geochemical characteristics, studied rocks contain tonalite, granodiorite, granite and alkali granite. These rocks are metaluminous, weakly peraluminous, high-K, and calc-alkaline. The behavior of Y, Ba, Ce and Zr vs. SiO2 display the properties of the high temperature I-type granites. These granitoids plot in the field of VOG. Enriched LREE and LILE with depleted HFSE show characteristics of subduction related active continental margins. The ratios of Nb/U and Nb/La and Sm/Yb indicate the crustal contamination. Isotopic data and La vs. La/Sm diagram show the role of the lower crust and the old continental crust in magma evolution. According to the phenocrysts assemblage, REE pattern with negative Eu anomaly and La/Yb ratio to crustal thickness, studied rocks are fractionated from relatively dry magma which has undergone from shallow depths. Sm/Yb and La/Yb ratio display the mantle source is garnet-free source. The low to moderate degree of partial melting of garnet-free amphibolite is the source of the studied granitoids. Volatiles that is driven from subduction slab and melt of the subducted sediments play a significant role in the generation and evolution of their magma source.
