Stern, Robert J. and Ali, Kamal and Asimow, Paul D. and Azer, Mokhles K. and Leybourne, Matthew I. and Mubarak, Heba S. and Ren, Minghua and Romer, Rolf L. and Whitehouse, Martin J. (2020) Atud Gabbro-Diorite Complex: Glimpse of the Cryogenian Mixing, Assimilation, Storage, and Homogenization Zone beneath the Eastern Desert of Egypt. Journal of the Geological Society, 117 (5). pp. 965-980. ISSN 0016-7649. doi:10.1144/jgs2019-199. https://resolver.caltech.edu/CaltechAUTHORS:20200513-071910901
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Abstract
We analysed gabbroic and dioritic rocks from the Atud igneous complex in the Eastern Desert of Egypt to understand better the formation of juvenile continental crust of the Arabian–Nubian Shield. Our results show that the rocks are the same age (U–Pb zircon ages of 694.5 ± 2.1 Ma for two diorites and 695.3 ± 3.4 Ma for one gabbronorite). These are partial melts of the mantle and related fractionates (εNd₆₉₀ = +4.2 to +7.3, ⁸⁷Sr/⁸⁶Sr_i = 0.70246–0.70268, zircon δ¹⁸O ∼ +5‰). Trace element patterns indicate that Atud magmas formed above a subduction zone as part of a large and long-lived (c. 60 myr) convergent margin. Atud complex igneous rocks belong to a larger metagabbro–epidiorite–diorite complex that formed as a deep crustal mush into which new pulses of mafic magma were periodically emplaced, incorporated and evolved. The petrological evolution can be explained by fractional crystallization of mafic magma plus variable plagioclase accumulation in a mid- to lower crustal MASH zone. The Atud igneous complex shows that mantle partial melting and fractional crystallization and plagioclase accumulation were important for Cryogenian crust formation in this part of the Arabian–Nubian Shield.
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Additional Information: | © 2020 The Author(s). Published by The Geological Society of London. Received 2 December 2019; Revised 28 April 2020; Accepted 30 April 2020. We appreciate thoughtful and constructive reviews by J.-P. Liégeois and R. A. Terentiev. K. Lindén and H. Jeon are thanked for assistance with the SIMS analyses. The Nordsim laboratory operates as a Swedish Research Council infrastructure under grant 2017-00671; this is Nordsim contribution 639. This is UTD Geosciences contribution number 1353. This work was funded by the Directorate for Geosciences (OCE-1826310). Author contributions: RS: conceptualization (lead), formal analysis (lead), visualization (lead), writing – original draft (lead), writing – review & editing (lead); KA: investigation (supporting), visualization (supporting), writing – review & editing (supporting); PA: formal analysis (supporting), writing – original draft (supporting); MA: investigation (supporting), writing – original draft (supporting), writing – review & editing (supporting); MIL: investigation (supporting), visualization (supporting), writing – original draft (supporting), writing – review & editing (supporting); HSM: investigation (supporting), writing – original draft (supporting); MR: investigation (supporting), visualization (supporting), writing – original draft (supporting); RLR: investigation (equal), visualization (equal), writing – review & editing (equal); MW: investigation (equal), visualization (equal), writing – review & editing (equal). Data availability statement: All data generated or analysed during this study are included in this published article (and its supplementary information files). | ||||||||||||
Group: | Division of Geological and Planetary Sciences | ||||||||||||
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Issue or Number: | 5 | ||||||||||||
DOI: | 10.1144/jgs2019-199 | ||||||||||||
Record Number: | CaltechAUTHORS:20200513-071910901 | ||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20200513-071910901 | ||||||||||||
Official Citation: | The Atud gabbro–diorite complex: glimpse of the Cryogenian mixing, assimilation, storage and homogenization zone beneath the Eastern Desert of Egypt. Robert J. Stern, Kamal Ali, Paul D. Asimow, Mokhles K. Azer, Matthew I. Leybourne, Heba S. Mubarak, Minghua Ren, Rolf L. Romer and Martin J. Whitehouse. Journal of the Geological Society, 177, 965-980, 11 June 2020, https://doi.org/10.1144/jgs2019-199 | ||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||
ID Code: | 103162 | ||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||
Deposited By: | Tony Diaz | ||||||||||||
Deposited On: | 13 May 2020 15:28 | ||||||||||||
Last Modified: | 01 Jun 2023 23:33 |
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