Geochemistry and Petrogenesis of Late Ediacaran Rare-Metal Albite Granite of the Nubian Shield: Case Study of Nuweibi Intrusion, Eastern Desert, Egypt

Azer, Mokhles K.; Abdelfadil, Khaled M.; Ramadan, A. A.

doi:10.1086/705328

Cited by 24 publications

(21 citation statements)

References 103 publications

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“…The mode of emplacement of the ADAG is very similar to the Tarr albitite in southern Sinai (Azer et al, 2010(Azer et al, , 2019b and the Nuweibi albite granite in the Eastern Desert of Egypt (Azer et al, 2019a), despite the obvious differences in their chemical compositions. Each of these intrusions is divided into hypabyssal and porphyritic varieties suggesting that a gradient in emplacement depth extending to very shallow crustal levels is preserved and exposed in each case.…”

Section: Evidence For Magmatic Vs Metasomatic Effectsmentioning

confidence: 75%

“…The ADAG in particular has likewise been assigned by different authors to either magmatic (Asran, 1985;Mohamed, 1993;Jahn, 1996;Renno, 1997) or metasomatic origins (Sabet et al,1976;Kamel and E1 Tabbal, 1980). In fact, the distinction between magmatic and metasomatic processes may not be as absolute as once thought (Lundstrom, 2016;Azer et al, 2019aAzer et al, , 2020Seddik et al, 2020).…”

Section: Evidence For Magmatic Vs Metasomatic Effectsmentioning

confidence: 95%

“…This feature is characteristic of rare-metal bearing granites in the Eastern Desert of Egypt (e.g. Hassanen et al, 1995;Abdalla, 2009;Abu El-Rus et al, 2017;Azer et al, 2019a. The depletion in LREE has been variously attributed to fractionation of accessory phases such as monazite (Mittlefehldt and Miller, 1983) or to scavenging by a fluorine-rich fluid (Webb et al, 1985).…”

Section: Ree Characteristicsmentioning

confidence: 99%

“…13. Suggested model for the emplacement of the ADAG intrusion in a magmatic cupola (adapted from Azer et al 2019a).…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Geochemistry and Petrogenesis of Late Ediacaran Rare‐metal Albite Granites of the Arabian‐Nubian Shield

Amarah

Azer

Asimow

et al. 2021

Acta Geologica Sinica (Eng)

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The Abu Dabbab albite granite (ADAG), in the central Eastern Desert of Egypt, hosts the most significant rare metal ore deposit in the northern part of the Neoproterozoic Arabian-Nubian Shield. Here, we report detailed field, petrographic, mineralogical and geochemical investigation of the ADAG, an isolated stock-like granitic body with sharp intrusive contacts against metamorphic country rocks, probably emplaced at about 600 Ma. The fine-grained porphyritic upper unit is a preserved remnant of the shallowly-emplaced apex of the magma chamber, whereas the medium-grained lower unit crystallized at deeper levels under subvolcanic conditions. The peraluminous leucocratic ADAG shares common geochemical characteristics with post-collisional intraplate A-type magmas. In addition to the conspicuous enrichment in Na 2 O, the ADAG is remarkable for its anomalous concentrations of Ta, Nb, Li, Hf, Ga, Sn, Zn and heavy rare-earth elements. Nb-Ta minerals in the ADAG are mixed with Fe-Mn oxides, forming black patches that increase in abundance toward of the base of the intrusion. Columbite-tantalite, cassiterite and wolframite are the most important ore minerals. Pronounced negative Eu anomalies (Eu/Eu * = 0.10-0.24) reflect extreme magmatic fractionation and perhaps the effects of late fluid-rock interaction. The ADAG was most likely generated by partial melting of the juvenile middle crust of the ANS as the geotherm was elevated by erosional uplift following lithospheric delamination and it was emplaced at the intersection of lineations of structural weakness. Although formation of the ADAG and its primary enrichment in rare metals are essentially due to magmatic processes, late-stage metasomatism caused limited redistribution of rare metals. Fluid-driven subsolidus modification was limited to the apex of the magma chamber and drove development of greisen, amazonite, and quartz veins along fracture systems.

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Section: Evidence For Magmatic Vs Metasomatic Effectsmentioning

confidence: 75%

Section: Evidence For Magmatic Vs Metasomatic Effectsmentioning

confidence: 95%

Section: Ree Characteristicsmentioning

confidence: 99%

“…13. Suggested model for the emplacement of the ADAG intrusion in a magmatic cupola (adapted from Azer et al 2019a).…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Geochemistry and Petrogenesis of Late Ediacaran Rare‐metal Albite Granites of the Arabian‐Nubian Shield

Amarah

Azer

Asimow

et al. 2021

Acta Geologica Sinica (Eng)

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“…Generally, post-orogenic granites J o u r n a l P r e -p r o o f evolved from calc-alkaline (630-600 Ma) to alkaline (610-590 Ma) character, with some overlap in their ages (Ali et al, 2009;Eliwa et al, 2014). They include a number of discrete, shallowlyemplaced A-type and highly fractionated I-type igneous complexes, with significant enrichment in some ores (Helba et al, 1997;Abou El Maaty and Ali Bik, 2000;El Hadek et al, 2016;Abu El-Rus et al, 2017;Sami et al, 2017Sami et al, , 2018Heikal et al, 2019;Azer et al, 2019Azer et al, , 2020Seddik et al, 2020, Abuamarah et al, 2021. The abundance of these post-orogenic granites is of geodynamic interest, as they represent a significant addition of material into the juvenile crust of the ANS over a relatively short time interval.…”

Section: Introductionmentioning

confidence: 99%

Magmatic and hydrothermal evolution of highly-fractionated rare-metal granites at Gabal Nuweibi, Eastern Desert, Egypt

Moussa

Asimow

Azer

et al. 2021

Lithos

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Remote sensing techniques and geochemical constraints on the formation of the Wadi El-Hima mineralized granites, Egypt: new insights into the genesis and accumulation of garnets

Khedr

Khashaba

El-Shibiny

et al. 2022

Int J Earth Sci (Geol Rundsch)

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The Wadi El-Hima Neoproterozoic I- and A-type granites in the Southern Eastern Desert of Egypt are rich in garnets (up to 30 vol%) and are cut by NW–SE strike-slip faults, as confirmed from structure lineament extraction maps. These mineralized granites and garnet mineralization zones can be successfully discriminated using remote sensing techniques. Spectral angle mapper and matched filtering techniques are highly effective for mapping garnet-rich zones and show that the highest garnet concentrations occur along the intrusive contact zone of NW–SE striking faults. El-Hima granites have high SiO2 (73.5–75.1 wt%), Al2O3 (13.4–15.3 wt%) and total alkali (6.7–8.7 wt%) contents, suggesting that they were sourced from peraluminous (A/CNK > 1) parental magmas. Garnet-bearing trondhjemites are metasomatic in origin and formed after I-type tonalite-granodiorites, which originated in a volcanic arc tectonic setting. Garnet-rich syenogranites and alkali-feldspar granites are both post-collisional A-type granites: the syenogranites formed from peraluminous magmas generated by partial melting of lower crustal tonalite and metasedimentary protoliths during lithospheric delamination, and the alkali-feldspar granites crystallized from highly fractionated, felsic and alkali-rich peraluminous magmas in the upper crust. Garnets in El-Hima mineralized granites occur in three forms: (1) subhedral disseminated crystals, (2) vein-type crystals, and (3) aggregated subhedral crystals, reflecting different mechanisms of accumulation. All are dominantly almandine in composition (Alm76Sps10 Prp7Grs6Adr1) and have high average concentrations of heavy rare earth elements (HREE) (ΣHREE = 1636 ppm), Y = (3394 ppm), Zn (325 ppm), Li (39.17 ppm) and Ga (34.94 ppm). Garnet REE patterns show strong negative Eu anomalies with HREE enriched relative to LREE, indicating a magmatic origin. These magmatic garnets are late-stage crystallization products of Al-rich hydrous magmas, and formed at low temperature (680–730 °C) and pressure (2.1–2.93 kbar) conditions in the upper continental crust. Peculiar garnet concentrations in syenogranites near and along contact zones with alkali feldspar granites are related to peraluminous parent hydrous magma compositions. These garnets formed by in situ crystallization from A-type granite melts, alongside accumulation of residual garnets left behind after partial melting of the host garnet-rich granites along the intrusive contact. Magmatic-fluid flow along the NW–SE striking fault of Najd system enhanced garnet accumulation in melts, which formed clots and veins of garnet.

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Geochemistry and Petrogenesis of Late Ediacaran Rare-Metal Albite Granite of the Nubian Shield: Case Study of Nuweibi Intrusion, Eastern Desert, Egypt

Cited by 24 publications

References 103 publications

Geochemistry and Petrogenesis of Late Ediacaran Rare‐metal Albite Granites of the Arabian‐Nubian Shield

Geochemistry and Petrogenesis of Late Ediacaran Rare‐metal Albite Granites of the Arabian‐Nubian Shield

Magmatic and hydrothermal evolution of highly-fractionated rare-metal granites at Gabal Nuweibi, Eastern Desert, Egypt

Remote sensing techniques and geochemical constraints on the formation of the Wadi El-Hima mineralized granites, Egypt: new insights into the genesis and accumulation of garnets

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