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Magmatic and post-magmatic evolution of post-collisional rare-metal bearing granite: The Neoproterozoic Homrit Akarem Granitic Intrusion, south Eastern Desert of Egypt, Arabian-Nubian Shield

Abuamarah, Bassam A. and Azer, Mokhles K. and Seddik, Amany M. A. and Asimow, Paul D. and Guzman, Pedro and Fultz, Brent T. and Wilner, M. J. and Dalleska, Nathan and Darwish, Mahmoud H. (2022) Magmatic and post-magmatic evolution of post-collisional rare-metal bearing granite: The Neoproterozoic Homrit Akarem Granitic Intrusion, south Eastern Desert of Egypt, Arabian-Nubian Shield. Chemie der Erde - Geochemistry, 82 (1). Art. No. 125840. ISSN 0009-2819. doi:10.1016/j.chemer.2021.125840.

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The Homrit Akarem granitic intrusion (HAGI) outcrops near the western edge of the south Eastern Desert basement exposure in Egypt. It is a composite of two cogenetic intrusive bodies: an early albite granite phase shallowly emplaced at the apex of a magmatic cupola, and a later subjacent pink granite phase with a marginal zone of muscovite granite and better preservation of magmatic features. Mineral chemistry of primary biotite and garnet, together with whole-rock chemistry, identify the HAGI as a highly fractionated A-type peraluminous intrusion. The chemistry of F-dominant, Li-bearing, Fe³⁺-rich primary magmatic mica in the pink granite resembles that typically found in highly evolved Nb-Y-F pegmatites. The HAGI is the evolved product of a primary magma generated by partial melting of juvenile crust of the Arabian-Nubian Shield (ANS), emplaced along a regional strike-slip fault system that promoted its ascent. The main emplacement mechanism and evolutionary sequence of the HAGI was magmatic, although secondary minerals and textures resulting from hydrothermal fluid interactions are observed, especially at its margins. Primary columbite-(Mn) crystallized from melt and was partly replaced by secondary fluorcalciomicrolite. The high fluorine content of magmatic fluids exsolved from the intrusion is indicated by quartz-fluorite veins, greisenization, albitization, and F-bearing secondary oxide minerals. The magmatic derivation of this fluid is demonstrated by the F-dominant primary mica, a siderophyllite-polylithionite solid solution commonly known as zinnwaldite. The chemistry of zinnwaldite constrains the F/OH activity ratio and oxygen fugacity of its parental melt and thereby resolves the ambiguity between pressure and the effects of F in controlling the normative quartz content of rare-metal granites. The HAGI is less mineralized than the post-collisional rare-metal granites found further east in the south Eastern Desert, replicating a trend observed previously in the central Eastern Desert and suggesting that east-west zoning in rare metal enrichment is a persistent feature across latitudes at the western edge of the ANS.

Item Type:Article
Related URLs:
URLURL TypeDescription
Abuamarah, Bassam A.0000-0001-8272-0367
Azer, Mokhles K.0000-0002-3711-8630
Asimow, Paul D.0000-0001-6025-8925
Fultz, Brent T.0000-0002-6364-8782
Dalleska, Nathan0000-0002-2059-1587
Darwish, Mahmoud H.0000-0002-8930-6422
Additional Information:© 2021 Elsevier. Received 2 September 2021, Revised 4 November 2021, Accepted 10 November 2021, Available online 15 November 2021. The authors would like to extend their appreciation and gratitude to the King Saud University, Riyadh, Saudi Arabia for funding and supporting this work through Researchers Supporting Project number (RSP-2021/151). PDA’s participation is supported by NSF award 1947616. The authors are also indebted to the editor (Prof. Astrid Holzheid) for her efforts and numerous helpful comments. In addition, the authors highly appreciate thoughtful reviews by the two anonymous reviewers. Credit authorship contribution statement: Bassam A. Abuamarah: Review and editing; Mokhles K. Azer: Conceptualization; Data curation; Investigation; Visualization; Writing – original draft; Amany M. A. Seddik: Investigation; Writing; Review; Paul D. Asimow: Investigation; Methodology; Resources; Software; Validation; Review; Editing; Pedro Guzman: Chemical analyses; Brent T. Fultz: Chemical analyses; M. J. Wilner: Chemical analyses; Nathan Dalleska: Chemical analyses; Mahmoud H. Darwish: Review and editing. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funding AgencyGrant Number
King Saud UniversityRSP-2021/151
Subject Keywords:Arabian-Nubian Shield; Magmatic cupola; Post-collisional; Nb–Ta oxides; Magmatic–hydrothermal evolution
Issue or Number:1
Record Number:CaltechAUTHORS:20211202-191328092
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Official Citation:Bassam A. Abuamarah, Mokhles K. Azer, Amany M.A. Seddik, Paul D. Asimow, Pedro Guzman, Brent T. Fultz, M.J. Wilner, Nathan Dalleska, Mahmoud H. Darwish, Magmatic and post-magmatic evolution of post-collisional rare-metal bearing granite: The Neoproterozoic Homrit Akarem Granitic Intrusion, south Eastern Desert of Egypt, Arabian-Nubian Shield, Geochemistry, Volume 82, Issue 1, 2022, 125840, ISSN 0009-2819,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112173
Deposited By: George Porter
Deposited On:02 Dec 2021 22:43
Last Modified:23 Mar 2022 22:39

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