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Mineralogical and geochemical study of rodingites and associated serpentinized peridotite, Eastern Desert of Egypt, Arabian-Nubian Shield

Mubarak, Heba S. and Azer, Mokhles K. and Surour, Adel A. and Moussa, Hilmy E. and Asimow, Paul D. and Kabesh, Mona (2020) Mineralogical and geochemical study of rodingites and associated serpentinized peridotite, Eastern Desert of Egypt, Arabian-Nubian Shield. Lithos, 374-375 . Art. No. 105720. ISSN 0024-4937. https://resolver.caltech.edu/CaltechAUTHORS:20200812-083037133

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Abstract

We studied rodingite and rodingite-like rocks within a serpentinized ultramafic sequence and ophiolitic mélange at Um Rashid, in the Eastern Desert of Egypt. The Um Rashid ophiolite is strongly deformed, metamorphosed, and altered by serpentinization, carbonatization, listvenitization, rodingitization and silicification. The textures, whole-rock chemistry, and composition of fresh primary mineral relics show that the serpentinite protoliths were strongly melt-depleted harzburgite and minor dunite, typical of a supra-subduction zone fore-arc setting. The light-colored rocks replacing gabbro are divided on the basis of field relations, mineral assemblages and geochemical characteristics into typical rodingite and rodingite-like rock. Typical rodingite, found as blocks with chloritite blackwall rims within ophiolitic mélange, contains garnet, vesuvianite, diopside and chlorite with minor prehnite and opaque minerals. Rodingite-like rock, found as dykes in serpentinite, consists of hercynite, preiswerkite, margarite, corundum, prehnite, ferropargasite, albite, andesine, clinozoisite and diaspore. Some rodingite-like rock samples preserve relict gabbroic minerals and texture, whereas typical rodingite is fully replaced. Rodingite is highly enriched in CaO, Fe₂O₃, MgO, and compatible trace elements, whereas rodingite-like rock is strongly enriched in Al₂O₃ and incompatible trace elements. Based on geochemistry and petrographic evidence, both types of rodingitic rocks likely developed from mafic protoliths in immediate proximity to serpentinite but were affected by interaction with different fluids, most likely at different times. Typical rodingite development likely accompanied serpentinization and shows mineral assemblages characteristic of low-Si, high-Ca fluid infiltration at about 300 °C. Rodingite-like rock, on the other hand, likely developed from seawater infiltration.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.lithos.2020.105720DOIArticle
ORCID:
AuthorORCID
Azer, Mokhles K.0000-0002-3711-8630
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2020 Elsevier B.V. Received 27 June 2020, Revised 28 July 2020, Accepted 28 July 2020, Available online 12 August 2020. We acknowledge the National Research Centre (NRC), Egypt for logistical support of this work. The present manuscript is a part of the master's thesis of Heba S. Mubarak (the first author). PDA is supported by the US NSF, award 1947616. The authors are also indebted to the editor (Prof. Michael Roden) and two reviewers (Prof. Abdel-Aal M. Abdel-Karim and anonymous reviewer) for their efforts and numerous helpful comments. 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.
Funders:
Funding AgencyGrant Number
National Research Centre (Egypt)UNSPECIFIED
NSF1947616
Subject Keywords:Arabian-Nubian Shield; Rodingitization; Carbonatization; Garnet; Vesuvianite; Hercynite; Margarite; Preiswerkite
Record Number:CaltechAUTHORS:20200812-083037133
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200812-083037133
Official Citation:Heba S. Mubarak, Mokhles K. Azer, Adel A. Surour, Hilmy E. Moussa, Paul D. Asimow, Mona M.L. Kabesh, Mineralogical and geochemical study of rodingites and associated serpentinized peridotite, Eastern Desert of Egypt, Arabian-Nubian Shield, Lithos, Volumes 374–375, 2020, 105720, ISSN 0024-4937, https://doi.org/10.1016/j.lithos.2020.105720. (http://www.sciencedirect.com/science/article/pii/S0024493720303571)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104924
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Aug 2020 15:42
Last Modified:27 Aug 2020 18:05

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