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Atud Gabbro-Diorite Complex: Glimpse of the Cryogenian Mixing, Assimilation, Storage, and Homogenization Zone beneath the Eastern Desert of Egypt

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 . ISSN 0016-7649. (In Press) https://resolver.caltech.edu/CaltechAUTHORS:20200513-071910901

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Abstract

We analyzed 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 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/⁸⁶Sri = 0.70246 to 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 (∼60 Ma) 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 petrologic 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 was important for Cryogenian crust formation in this part of the Arabian-Nubian Shield.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1144/jgs2019-199DOIArticle
https://doi.org/10.6084/m9.figshare.c.4958822DOISupplementary Material
ORCID:
AuthorORCID
Stern, Robert J.0000-0002-8083-4632
Ali, Kamal0000-0002-7332-7843
Asimow, Paul D.0000-0001-6025-8925
Azer, Mokhles K.0000-0002-3711-8630
Whitehouse, Martin J.0000-0003-2227-577X
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 Jean-Paul Liégeois and Roman A. Terentiev. Kerstin Lindén and Heejin 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.
Funders:
Funding AgencyGrant Number
NSFOCE-1826310
Swedish Research Council2017-00671
Record Number:CaltechAUTHORS:20200513-071910901
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200513-071910901
Official Citation:Robert J. Stern, Kamal Ali, Paul D. Asimow, Mokhles K. Azer, Matthew I. Leybourne, Heba S. Mubarak, Minghua Ren, Rolf L. Romer, Martin J. Whitehouse; The 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 doi: 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:13 May 2020 15:28

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