The Egyptian Granitoids: an up-to-date Synopsis

El‐Naby, Hamdy H. Abd

doi:10.1007/978-3-030-49771-2_9

Cited by 6 publications

(5 citation statements)

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“…The evolution of the basement rocks in the ANS during the Neoproterozoic rocks (850-590 Ma) involved three major stages: (1) pre-collisional, (2) collisional, and (3) postcollisional [2,3]. Ophiolites and metamorphosed volcano-sedimentary successions were formed during the pre-collisional stage (850-700 Ma).…”

Section: Geological Setting and Field Observationmentioning

confidence: 99%

“…The Eastern Desert of Egypt, as a part of the Neoproterozoic Arabian-Nubian Shield (ANS), is occupied by voluminous masses of granitic rocks that formed from different melt compositions and emplaced in different tectonic regimes (e.g., [1][2][3]). In the Gebel El Bakriyah area, which is located in the central part of the Eastern Desert (CED), prominent granitic masses are present that have field and laboratory characteristics, which can be integrated with other rock units such as gabbros to build up a geodynamic model for better understanding of the ANS evolution.…”

Section: Introductionmentioning

confidence: 99%

“…They together constitute about 60% of plutonic rocks of the Nubian Shield in the Eastern Desert and can be classified and distinguished according to mineral and chemical compositions, magma type, tectonic setting, and age (e.g., [2,4,5]). In a recent review, [3] classified the Egyptian granitic rocks (mainly in the Eastern Desert and the Sinai Peninsula) based on the tectonic regime into four types namely, subductionrelated, collisional, calc-alkaline post-orogenic, and alkaline post-tectonic. The subductionrelated category (around 700-660 Ma, [6]) is represented by granitoids that are tholeiitic to calc-alkaline and is categorized as the older granitoids [6].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, collisionrelated granites (around 610-590 Ma, [7]) are medium-to high-K calc-alkaline and are represented by younger granites (monzo-to syenogranite) that have been formed by the lower continental crust melting (e.g., [6,8]. Calc-alkaline post-orogenic granite (between 590 and 540 Ma, [3]) is characterized by a high-K calc-alkaline to shoshonite nature and comprises A 2 -type younger granites, which originated from a melting process of lower crustal rocks in an extension setting during the transitional stage between orogenic and anorogenic regimes (e.g., [6,9]). The last phase of younger granites (A 1 -type) (around 540 Ma, [7]) is the alkaline post-tectonic granite formed by the differentiation of alkalibasaltic magmas (e.g., [9]).…”

Section: Introductionmentioning

confidence: 99%

“…Globally, A-type granites are classified into anorogenic and post-orogenic granites [10], and they represent the youngest phase of felsic magmatism in the Eastern Desert of Egypt and the entire ANS [2,3,11]. For the last three decades, A-type granites in the Eastern Desert attracted considerable attention because of their economic potentialities and occasional enrichment of rare metals (e.g., Nb, Ta, Sn, W, Be, and B), rare-earth elements (REEs) and radioactive materials [4,12].…”

Section: Introductionmentioning

confidence: 99%

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Integration of Whole-Rock Geochemistry and Mineral Chemistry Data for the Petrogenesis of A-Type Ring Complex from Gebel El Bakriyah Area, Egypt

Abd El-Fatah,

Surour,

Azer

et al. 2023

Minerals

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El Bakriyah Ring Complex (BRC) is a prominent Neoproterozoic post-collisional granite suite in the southern part of the Central Eastern Desert of Egypt. The BRC bears critical materials (F, B, Nb, and Ta) in appreciable amounts either in the form of rare-metals dissemination or in the form of fluorite and barite vein mineralization. The complex consists of inner syenogranite and outer alkali feldspar granite that have been emplaced in a Pan-African assemblage made up of granitic country rocks (granodiorite and monzogranite), in addition to post-collisional fresh gabbro as a part of the Arabian-Nubian Shield (ANS) in northeast Africa. Granites of the BRC are characterized by enrichment in silica, alkalis, Rb, Y, Ga, Nb, Ta, Th, and U and depletion in Sr, Ba, and Ti. Geochemical characterization of the BRC indicates that the magma is a crustal melt, which originated from the partial melting of metasedimentary sources. Concentrations of rare-earth elements (REEs) differ in magnitude from the ring complex and its granitic country rocks but they have similar patterns, which are sub-parallel and show LREEs enrichment compared to HREEs. The presence of a negative Eu anomaly in these rocks is related to plagioclase fractionation. The abundance of fluorine (F) in the different granite varieties plays an important role in the existence of a tetrad influence on the behavior of REEs (TE1, 3 = up to 1.15). Geochemical parameters suggest the crystallization of the BRC granite varieties by fractional crystallization and limited assimilation. Mn-columbite and Mn-tantalite are the most abundant rare-metals dissemination in the BRC granite varieties. We present combined field, mineralogical and geochemical data that are in favor of magma originating from a metasedimentary source for the BRC with typical characteristics of A-type granites. Our geodynamic model suggests that the Gebel El Bakriyah area witnessed the Neoproterozoic post-collisional stage of the ANS during its late phase of formation. This stage was characterized by the emplacement of fresh gabbros followed by the syenogranite and alkali-feldspar granite of the BRC into an arc-related assemblage (granodiorite and monzogranite). It is believed that the mantle-derived magma was interplated and then moved upward in the extensional environment to a shallower level in the crust owing to events of lithospheric delamination. This presumably accelerated the processes of partial melting and differentiation of the metasedimentary dominated source (Tonian-Cryogenian) to produce the A-type granites building up the BRC (Ediacaran).

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Section: Geological Setting and Field Observationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%