Late Proterozoic older granitoids from the North Eastern desert of Egypt: petrogenesis and geodynamic implications

Mahallawi, M.M. El; Ahmed, Moustafa

doi:10.1007/s12517-010-0132-3

Cited by 11 publications

(3 citation statements)

References 48 publications

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“…1b). The Cryogenian granite intrusions are formed by either fractional crystallization of mafic crustal-derived melts generated by melting of the amphibolitic lower crust (Moghazi, 1999;Farahat et al 2007;El-Mahallawi & Ahmed, 2012;Basta et al 2017) or by fractional crystallization of mantle-derived mafic magma with assimilation (Eliwa et al 2014;El-Bialy & Omar, 2015). The Ediacaran granite intrusions have geochemical characteristics of highly fractionated calc-alkaline I-type granites and A-type granites of alkaline affinity (El-Sayed, 1998;El-Sayed et al 1999;Abd El-Ghaffar & Ramadan, 2018).…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

et al. 2021

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The Abu Kharif area in the Northern Eastern Desert consists of contrasting granitic magma suites: a Cryogenian granodiorite suite (850–635 Ma), an Ediacaran monzogranite suite (635–541 Ma) and a Cambrian alkali riebeckite granite suite (541–485 Ma). Tungsten mineralization occurs within W-bearing quartz veins and a disseminated type confined to the monzogranite. Whole-rock geochemical data classify the granodiorite as a late-orogenic I-type with calc-alkaline affinity, while the monzogranite and alkali riebeckite granite represent respectively a post-orogenic highly fractionated I-type with calc-alkaline affinity and an anorogenic A1-subtype with alkaline affinity. Geochemical modelling indicates that the three intrusions represent separate magmatic pulses where the granodiorite was generated by ∼75 % batch partial melting of an amphibolitic source followed by fractional crystallization of hornblende, biotite, apatite and titanite. The monzogranite was formed by 62 % batch partial melting of the normal ‘non-metasomatized’ Pan-African crust of calc-alkaline granite composition followed by fractional crystallization of plagioclase, biotite, K-feldspar, magnetite, ilmenite, with minor apatite and titanite. The alkali riebeckite granite was generated by 65 % batch partial melting of metasomatized Pan-African granite source followed by fractional crystallization of plagioclase, K-feldspar, amphibole and biotite with minor magnetite, apatite and titanite. In general, the parent magmas of the three intrusions were originally enriched in W, but with different concentrations. This W-enrichment would be caused by magmatic-related hydrothermal volatile-rich fluids and concentrated within the monzogranite.

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Section: Introductionmentioning

confidence: 99%

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

et al. 2021

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“…The Egyptian granitoid rocks were classified into (1) older granitoids, which range in composition from quartz diorite to granodiorite. They are syn-orogenic calc-alkaline I-type granitoids and were emplaced during the collisional stage between 665 and 614 Ma (Moghazi 2002;Moussa et al 2008;El Mahallawi and Ahmed 2012); (2) younger granitoids, which range in composition from monzogranites through syenogranites to alkali-feldspar granites. They are fractionated calc-alkaline I-type granites as well as A-type granites.…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of Maktali fractionated calc-alkaline younger granitoids, Central Eastern Desert, Egypt

et al. 2019

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The Egyptian calc-alkaline younger granitoids represent part of broadly distributed late collisional high-K calc-alkaline granitoids in the northern Arabian-Nubian Shield. In the Eastern Desert of Egypt, these granitoids have a significant economic value that they are commonly associated with rare metal-bearing granites. Maktali granitoids are located in Central Eastern Desert and they constitute a two-phase pluton, which consists of leucogranites and monzogranites. They intrude the country metavolcanics with sharp contacts. These granitoids are slightly peraluminous and moderately to highly fractionated high-K calc-alkaline granitoids. Leucogranites and monzogranites were emplaced at temperatures 699.8-8.28.8°C and 757.2-909.6°C and under pressure 1.22-4.8 and 2.36-2.98 kbars respectively. Leucogranites and monzogranites were emplaced at depths 3.28-22.96 km and 6.36-8.5 km and they were crystallized under log Oxygen fugacity between − 13.2 to − 16.1 and − 11.6 to − 14.7 respectively. They are magnetite-series granitoids and their crystallization was controlled by NNO fugacity buffer. Leucogranites and monzogranites share the same magmatic source and they were emplaced during late-collisional stage by melting of crustal source rocks may occur as a consequence of decompression following delamination of the lithospheric root and slab breakoff. Maktali leucogranites could be generated by partial melting and subsequent fractional crystallization of mafic lower crust with addition of melts from the mantle. Maktali monzogranites show distinctive characteristics of rare metal-bearing granites that they contain Fe-columbite and transitional micas. Field and textural evidences together with chemistry of columbite, micas, and trace element behavior suggest the magmatic origin of monzogranites. Moreover, REEs in monzogranites show a pronounced Eu anomaly and a well-visible tetrad effect, supporting their generation by fractional crystallization and fluid-rock interaction during the late stage of granite crystallization.

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“…mantle-derived melts. (E.g., El-Sayed and Nisr, 1999;Moghazi et al, 2004;Moghazi, 2002;Farahat et al, 2011;Ali et al, 2012Ali et al, , 2013Ali et al, , 2016El Mahallawi and Ahmed, 2012;Azer, 2013;Eliwa et al, 2014;Mahdy et al, 2015;El-Bialy and Omar, 2015;Asran et al, 2017;Sami et al,2018;El-Bialy and Shata, 2018). Hussein et al (1982) divided the Egyptian younger granites into suture-related granites (G2-granite) formed in post-orogenic environment and intraplate granites (G3-granite) related to rifting processes.…”

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confidence: 99%

Geological, Geochemical, and Petrogenetic Aspects of Late Neoproterozoic Younger Granites at Wadi Um Sidra-Wadi Um Asmer Area, North Eastern Desert, Egypt.

2020

Egyptian Journal of Geology

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The late Neoproterozioc younger granites in the study area are classified into monzogranites, syenogranites and alkali feldspar granites according to the field, petrography and geochemical investigations. Monzogranites are mainly exposed along W. Um Sidra at G. Abu Mesaid in the eastern parts of the study area, intruding the Dokhan volcanic with sharp contacts. Syenogranites are exposed at G. El Shagola, G. Abu Harba, G Abu Mesaid, and some parts along W. Um Sidra intrude the metavolcanics and Dokhan volcanics with sharp contacts and contain enclaves of them. Alkali feldspar granites are exposed at G. El Shaylah, G. Urf El Eir, G. El Hurus, and the western exposures of G. Abu Harba intruding the metavolcanics and Dokhan volcanics with sharp and irregular contacts. The K/Rb, Ba/Rb and Rb/Sr ratios for the studied granites indicate that they were originated from highly differentiated magma and have been formed by partial melting of granitic crustal rocks. These granites were generated in possible extension-related environment and in a post-collision granites environment. The post-collision granites have calc-alkalic affinites, metaluminous to slightly peraluminous, and exhibit most of the characteristics of highly fractionated I-type granites derived from tonalites (intermediate magmas) of crustal sources. The studied monzogranites and syenogranites have generated at moderate/high water pressure in the 3 -8 kbar and temperatures of about 660ºC -685ºC, while the alkali feldspar granites were crystallizated at low water vapor pressure about 1 kbar and temperature abour 660 ºC., suggesting crystallization at relatively shallow depth between 20 and 30 km. The crystal-liquid equilibrium was the dominant mechanism involved in the genesis of these granites. The monzogranites and syenogranites have been generated at greater depth >30 km of the lower crust.The overall decreasing trends in FeO t , MgO, CaO, TiO 2 , and P 2 O 5 with increasing SiO 2 coupled with increasing Rb, Y,Th and Nb and the fractionated nature of the REE [(La/Lu) n = 3.67-14.21] suggesting that the fractional crystallization was played the major role during the evolution of the studied granites.

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Late Proterozoic older granitoids from the North Eastern desert of Egypt: petrogenesis and geodynamic implications

Cited by 11 publications

References 48 publications

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

Petrogenesis of contrasting magmatic suites in the Abu Kharif area, Northern Eastern Desert, Egypt: implications for Pan-African crustal evolution and tungsten mineralization

Petrogenesis of Maktali fractionated calc-alkaline younger granitoids, Central Eastern Desert, Egypt

Geological, Geochemical, and Petrogenetic Aspects of Late Neoproterozoic Younger Granites at Wadi Um Sidra-Wadi Um Asmer Area, North Eastern Desert, Egypt.

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