Sami, Mabrouk, Faisal, Mohamed, Leybourne, Matthew, Sanislav, Ioan V., Ahmed, Mohamed S., and Lasheen, El Saeed R. (2024) Unravelling the genesis and depositional setting of Neoproterozoic banded iron formation from central Eastern Desert, Egypt. Frontiers in Earth Science, 12. 1359617.

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Abstract

The Neoproterozoic banded iron formations (BIFs) are widely occurred in the Egyptian Eastern Desert. This study integrates field observations, petrographic studies, geochemical data, and lead isotopes to construct the genesis and depositional environment of Wadi El-Mis hama BIF deposits. The iron layers, primarily of oxide facies within a volcano-sedimentary sequence, comprise magnetite-rich beds alternating with jaspilite or silicate laminae. The studied BIFs exhibit a dominant composition of SiO2 and Fe2O3t with relatively low contents of TiO2 and Al2O3. The positive correlation of REEs (La, Sm, Yb) with Zr and low concentrations of HFSEs (Ta, Nb, Th, Hf) indicate a primary formation mechanism of chemical precipitation, maintaining original geochemical signatures. Geochemical patterns show depletion in LREEs, enrichment in HREEs (La/YbPAAS = 0.08–0.12), and positive La anomalies (La/LaPAAS = 1.15–8.57), consistent with seawater influence. Additionally, various geochemical discrimination diagrams supported by elevated super-chondritic Y/Ho values (29.6–38.7), weak positive Eu anomalies, and low contents of transition metals (Cu and Zn), point to the interaction of low-temperature (<200°C) hydrothermal fluids (bearing Fe and Si) with seawater during the deposition of the BIFs. The lack of significant negative Ce anomalies along with low Ni/Co, U/Th, and Cu/Zn ratios, imply that the iron mineralization was precipitated from dysoxic to oxic conditions. The geochemical and Pb isotopic data suggest that the iron deposits formed in an extensional geodynamic setting (intra-oceanic arc basin environment) due to the subduction of the Mozambique Plate, with signatures closely matching other Precambrian Algoma-type BIFs.

Item ID:	82620
Item Type:	Article (Research - C1)
ISSN:	2296-6463
Keywords:	banded iron formations, Algoma-type, Egyptian Eastern Desert, back-arc basin, Pb-isotopes
Copyright Information:	© 2024 Sami, Faisal, Leybourne, Sanislav, Ahmed and Lasheen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CCBY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Date Deposited:	03 May 2024 00:59
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370509 Sedimentology @ 50% 37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 10% 37 EARTH SCIENCES > 3703 Geochemistry > 370302 Inorganic geochemistry @ 40%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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