University of Isfahan Petrological Journal 2228-5210 7 27 2016 09 22 Geochemistry and petrogenesis of the Dehe Bala calc-alkaline granodiorites, south west of Boein Zahra Geochemistry and petrogenesis of the Dehe Bala calc-alkaline granodiorites, south west of Boein Zahra 147 170 21022 10.22108/ijp.2016.21022 FA Zeynab Gharamohammadi School of Geology, College of Sciences, University of Tehran, Tehran, Iran Ali Kananian School of Geology, College of Sciences, University of Tehran, Tehran, Iran Journal Article 2016 01 04 The Dehe Bala pluton is exposed approximately 45 km south-west of Boein Zahra town, Qazvin province. This Pluton which intruded the Eocene volcano-sedimentary rocks of the Urumieh-Dokhtar Magmatic assemblage (UDMA), is mainly composed of granodiorite and produced narrow thermal metamorphic contact aureoles surrounding the intrusion. The body is characterized by SiO₂ content ranging from 64.2 to 66.9 wt%, high-k calc-alkaline nature and metaluminous character (A/CNK<1.1). On the primitive mantle-normalized trace element spider diagram, the intrusive rocks have similar trace element patterns with pronounced enrichment in Cs, Th, U, K, Zr and P, Ti, Nb and Ba depletion. Chondrite-normalized rare earth elements (REE_s) patterns display moderate negative Eu anomalies, enrichment of LREE_S relative to HREE_S and moderate fractionated REE_S pattern. The granodiorites under discussion, based on geochemical features, belong to I-type granitoids. Their low TiO₂ and P₂O₅ contents and high Th/Ta=6.23-9.35 ratios are characteristic of subduction-related magmatism. The Dehe Bala granodiorites display geochemical characteristics typical of magmatic arc intrusions related to an active continental margin. These criteria include their calc-alkaline nature, pronounced negative Nb anomaly, light-REE-enriched patterns and weak fractionation of MREE and HREE. Enrichment of incompatible elements such as La, Ce, Rb, Th, K and Nd coupled with negative anomalies of Ti, Ba, Eu, Nb and P suggest that the parent magma originated by partial melting of lower crust. The presence of mafic microgranular enclaves (MME_S) in granodiorites along with disequilibrium textures in plagioclase phenocrysts and also the attendance of plagioclase phenocrysts between host granodiorites and the MME across theboundary point to mixing of crustal magma with mantle-derived mafic magma. The Dehe Bala pluton is exposed approximately 45 km south-west of Boein Zahra town, Qazvin province. This Pluton which intruded the Eocene volcano-sedimentary rocks of the Urumieh-Dokhtar Magmatic assemblage (UDMA), is mainly composed of granodiorite and produced narrow thermal metamorphic contact aureoles surrounding the intrusion. The body is characterized by SiO₂ content ranging from 64.2 to 66.9 wt%, high-k calc-alkaline nature and metaluminous character (A/CNK<1.1). On the primitive mantle-normalized trace element spider diagram, the intrusive rocks have similar trace element patterns with pronounced enrichment in Cs, Th, U, K, Zr and P, Ti, Nb and Ba depletion. Chondrite-normalized rare earth elements (REE_s) patterns display moderate negative Eu anomalies, enrichment of LREE_S relative to HREE_S and moderate fractionated REE_S pattern. The granodiorites under discussion, based on geochemical features, belong to I-type granitoids. Their low TiO₂ and P₂O₅ contents and high Th/Ta=6.23-9.35 ratios are characteristic of subduction-related magmatism. The Dehe Bala granodiorites display geochemical characteristics typical of magmatic arc intrusions related to an active continental margin. These criteria include their calc-alkaline nature, pronounced negative Nb anomaly, light-REE-enriched patterns and weak fractionation of MREE and HREE. Enrichment of incompatible elements such as La, Ce, Rb, Th, K and Nd coupled with negative anomalies of Ti, Ba, Eu, Nb and P suggest that the parent magma originated by partial melting of lower crust. The presence of mafic microgranular enclaves (MME_S) in granodiorites along with disequilibrium textures in plagioclase phenocrysts and also the attendance of plagioclase phenocrysts between host granodiorites and the MME across theboundary point to mixing of crustal magma with mantle-derived mafic magma. https://ijp.ui.ac.ir/article_21022_3d631c8a20c089db97da8f54e9bfdf77.pdf