The calc-alkaline and adakitic volcanism of the Sabzevar structural zone (NE Iran): implications for the Eocene magmatic flare-up in Central Iran

Hadi Shafaii Moghadam, Federico Rossetti, Federico Lucci, Massimo Chiaradia, Axel Gerdes, Margarita Lopez Martinez, Ghasem Ghorbani, Mohsen Nasrabady

    Research output: Contribution to journalArticlepeer-review

    42 Citations (Scopus)

    Abstract

    A major magmatic flare-up is documented along the Bitlis-Zagros suture zone in Eocene-Oligocene times. The Cenozoic magmatism of intraplate Central Iran is an integrant part of this tectono-magmatic scenario. The Cenozoic magmatism of the Sabzevar structural zone consists of mostly intermediate to felsic intrusions and volcanic products. These igneous rocks have calc-alkaline and adakitic geochemical signatures, with nearly coincident zircon U-Pb and mica Ar-Ar ages of ca. 45 Ma. Adakitic rocks have quite low HREE and high Sr/Y ratio, but share most of their geochemical features with the calc-alkaline rocks. The Sabzevar volcanic rocks have similar initial Sr, Nd and Pb isotope ratios, showing their cogenetic nature. Nd model ages cluster tightly around ~. 0.2-0.3 Ga. The geochemistry of the Sabzevar volcanic rocks, along with their isotopic signatures, might strangle that an upper mantle source, metasomatized by slab-derived melts was involved in generating the Sabzevar calc-alkaline rocks. A bulk rock trace element modeling suggests that amphibole-plagioclase-titanite-dominated replenishment-fractional crystallization (RFC) is further responsible for the formation of the middle Eocene Sabzevar adakitic rocks. Extensional tectonics accompanied by lithospheric delamination, possibly assisted by slab break-off and melting at depth was responsible for the Eocene formation of the Sabzevar magmatic rocks and, more in general, for the magmatic "flare-up" in Iran.

    Original languageEnglish
    Pages (from-to)517-535
    Number of pages19
    JournalLithos
    Volume248-251
    DOIs
    Publication statusPublished - 1 Apr 2016

    Keywords

    • Adakitic rocks
    • Sr-Nd-Pb isotopes
    • Cenozoic magmatism
    • Flare-up
    • Sabzevar
    • Iran

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