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Scientific article
English

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

Published inLithos, vol. 248-251, p. 517-535
Publication date2016
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 concident 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 elements 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.

Keywords
  • Adakitic rocks
  • Sr–Nd–Pb isotopes
  • Cenozoic magmatism
  • Flare–up
  • Sabzevar
  • Iran
Citation (ISO format)
MOGHADAM, Hadi Shafaii et al. The calc–alkaline and adakitic volcanism of the Sabzevar structural zone (NE Iran): implications for the Eocene magmatic flare–up in Central Iran. In: Lithos, 2016, vol. 248-251, p. 517–535. doi: 10.1016/j.lithos.2016.01.019
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ISSN of the journal0024-4937
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