Repeated magmatic buildup and deep "hot zones" in continental evolution

the Cadomian crust of Iran

Hadi Shafaii Moghadam*, Q. L. Li, W. L. Griffin, R. J. Stern, O. Ishizuka, H. Henry, F. Lucci, S. Y. O'Reilly, G. Ghorbani

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The generation and differentiation of continental crust by arc magmatism is strongly influenced by episodes of high magmatic flux ("flare-ups"). Magmatic flare-ups encourage the development of deep crustal hot zones where magmatic differentiation and density stratification combine to form the upper felsic and lower mafic continental crust. Such processes, which are responsible for the construction of continental arc crust, are prolonged events, which build a ∼30-40 km arc crust over tens of million years (∼100 Myr). New zircon U-Pb data reveal that the construction of Cadomian crust from NE Iran occurred over ∼15 ± 0.3 Myr. However, compiled zircon U-Pb ages reveal a prolonged magmatic flare-up of ∼45 Myr; ∼570 to 525 Ma. Basement outcrops in NE Iran expose lower- and upper crust that show how magmatic-geochemical differentiation occurred deep beneath a Cadomian continental arc in a crustal hot zone. Isotopic data for igneous rocks produced during this 45 Myr episode reveal interactions between mantle-derived melts and old continental crust. Synthesis of new and published data indicates that this type of interaction is common during periods of high magmatic fluxes. Our results indicate that differentiation of mafic melts in the lower crust during prolonged magmatic flare-ups plays a key role in building a stratified continental crust.

Original languageEnglish
Article number115989
Pages (from-to)1-16
Number of pages16
JournalEarth and Planetary Science Letters
Volume531
DOIs
Publication statusPublished - 1 Feb 2020

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Keywords

  • continental crust
  • magmatic flare-up
  • hot zone
  • Cadomian
  • Iran

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