Repeated magmatic buildup and deep “hot zones” in continental evolution: The Cadomian crust of Iran.

Shafaii Moghadam, Hadi , Li, Q. L. , Griffin, W. L. , Stern, R. J., Ishizuka, O. , Henry, H., Lucci, F. , O'Reilly, S. Y. and Ghorbani, G. (2020) Repeated magmatic buildup and deep “hot zones” in continental evolution: The Cadomian crust of Iran. Earth and Planetary Science Letters, 531 . Art.Nr. 115989. DOI 10.1016/j.epsl.2019.115989.

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Supplementary data:

Abstract

Highlights

• Cadomian continental arc crust of NE Iran was built during ∼15 Myr of magmatism.
• Magmatic flare-up in Iran Cadomia occurred over ∼45 Myr; 570 to 525 Ma.
• Geochemical differentiation in “hot zones” built the stratified continental crust of Iran.

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.

Document Type: Article
Keywords: continental crust, magmatic flare-up, hot zone, Cadomian, Iran
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Date Deposited: 16 Dec 2019 11:20
Last Modified: 08 Feb 2023 09:34
URI: https://oceanrep.geomar.de/id/eprint/48364

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