sayed zia Hosseini; Mahbobeh Iranmanesh
Abstract
The Oligocene-Miocene Daredesk pluton, located in southeastern part of the Urumieh–Dokhtar magmatic assemblage, is outcropped in the Eocene volcanic rocks in northeastern Jiroft. The pluton comprises mainly of diorite, quartz diorite, quartz monzodiotrite and granodiorite with metaluminous and ...
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The Oligocene-Miocene Daredesk pluton, located in southeastern part of the Urumieh–Dokhtar magmatic assemblage, is outcropped in the Eocene volcanic rocks in northeastern Jiroft. The pluton comprises mainly of diorite, quartz diorite, quartz monzodiotrite and granodiorite with metaluminous and calcalkaline affinity. They have petrographic and geochemical characteristics of I-type granitoids. Condrite and MORB normalized multi element spider diagrams for the Daredesk granitoid rocks show marked negative Ti, Nb and Ta anomaly and an enrichment of LILE (e.g Rb, Cs snd Ba). This feature together with other geochemical specifications, tectonic discrimination diagrams and geological position of the Daredesk pluton indicate its formation in an active continental margin setting. Also, chondrite-normalized rare earth element patterns of the Daredesk intrusive rocks show a gentle slope with (La/Yb)n= 3-6/4, indicate nonexistence of garnet as a residual phase in the source. All these features together with the occurrences of mafic microgranular enclaves, MgO and Cr contents, Th/Rb, Nb/Yb, Rb/Sr and Ba/Rb ratios clearly show that the Daredesk granitoid rockes formed by interaction between a primary mafic magma, produced by partial melting of metasomatized lithospheric mantle, with lower crust.
