Geology, Geochemistry and Radioactivity of Granitic and Volcanic Rocks Athadarba Area, South Eastern Desert, Egypt

Hassan, Azza; Shahin, Masoud S . Masoud; Bayoumi, Moustafa M.

doi:10.21608/absb.2015.22628

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…Rounded zircons (Figs. 4B and 5B) are likely produced during cooling of the magma in which the mineral crystallized (Spotts 1962;Hassan 1985;Higazy et al 1986).…”

Section: Discussionmentioning

confidence: 99%

Thorite inclusions in zircon of the monzogranite, Lower Nubia, SW Egypt

Hassan,

Brunarska

2023

Mineralogia

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This report presents the results of a petrographical and mineralogical (optical microscopy, BSE-EDS image analysis) study of zircon in samples from the Lower Nubian monzogranite. The mineral occurs as smaller grains (< 80 μm) in a fine-grained quartz-feldspar-matrix, coexisting with other accessory minerals including biotite, clinochlore, titanite, and britholite-(Ce). Zircon is also present within biotite and britholite-(Ce), suggesting that it started crystallization at about the same time as these two minerals. Two types of thorite inclusions within zircon are reported in this study. Type 1 is widely distributed throughout the zircon grain, forming crystallites of which each is typically < 1 μm in size. Type 2 is relatively larger (5-15 μm) and occurs only in one part of the grain. For the thorite inclusions, three possible origins are briefly discussed: (1) exsolution of thorite from zircon; (2) dissolution/reprecipitation of zircon; and (3) growth syngenetically with zircon. Of these potential hypotheses, the syngenetic growth model seems more favorable for zircon-thorite intergrowths than the other two hypotheses. Thorite inclusions and their host zircons seem to have grown from magma rather than hydrothermal or supercritical solutions. Here, they have primary textures and consistent chemical compositions that are consistent with whole-rock geochemistry.

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“…Rounded zircons (Figs. 4B and 5B) are likely produced during cooling of the magma in which the mineral crystallized (Spotts 1962;Hassan 1985;Higazy et al 1986).…”

Section: Discussionmentioning

confidence: 99%

Thorite inclusions in zircon of the monzogranite, Lower Nubia, SW Egypt

Hassan,

Brunarska

2023

Mineralogia

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“…In this respect, small intrusive bodies of A-type granitic rocks from Gabal El Dob area, northern Eastern Desert of Egypt, were selected in this study. This region has been previously investigated by Abdel Rahman (2006), Shahin (2015), Hammed et al (2020), andEl-Naggar et al (2022). The purpose of this paper is to investigate the geochemical characterizations of these granites to clarify their petrogenesis.…”

Section: Introductionmentioning

confidence: 99%

Geochemical characterizations and rare metal exploration of post-orogenic and anorogenic A-type granites from the Gabal El Dob area, Eastern Desert, Egypt.

Hamid

2023

Egyptian Journal of Geology

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HE orogenic older granitoids of Gabal El Dob area were intruded by post-tectonic younger granitoids, which predominated by alkali feldspar granite and alkali riebeckite granite. These granites occur as two separated and elongated bodies emplaced along a shear zone trending NNE. They are discriminated according to their petrographical studies into subsolvus and hypersolvus granites. Both granitic types consist essentially of perthites and quartz with little amount of plagioclase. The accessory assemblages along the two granitic phases are differing in their quantity and constituents. The hypersolvus granite contains arfvedsonite and riebeckite, which dominantly enclose variable amount of zircon and allanite. Overall, the studied granites are silica and alkali-rich with low contents of MgO, CaO and TiO 2 . Comparative geochemical studies indicated that the hypersolvus granite is enriched in total alkalis, Ga, Zr, Nb, Y and ΣREE relative to subsolvus granite. The two granitic phases display REE patterns, characterized by moderately fractionated LREE and nearly flat HREE with a moderate negative Eu anomaly. The subsolvus granite has transitional characteristics between A-type and fractionated I-type granites, but the hypersolvus granite has the most characteristics of A-type granites. The high concentrations of ΣREE in the hypersolus granite (av. 530ppm) are interpreted to the high abundance of REE-bearing allanite. The high contents of ΣREE and Zr in the hypersolvus granite along with the elevated background values of U and Th in both granitic phases could be used as an indicator for rare-metal exploration in Gabal El Dob area.

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Geology, Geochemistry and Radioactivity of Granitic and Volcanic Rocks Athadarba Area, South Eastern Desert, Egypt

Cited by 2 publications

References 3 publications

Thorite inclusions in zircon of the monzogranite, Lower Nubia, SW Egypt

Thorite inclusions in zircon of the monzogranite, Lower Nubia, SW Egypt

Geochemical characterizations and rare metal exploration of post-orogenic and anorogenic A-type granites from the Gabal El Dob area, Eastern Desert, Egypt.

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