<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>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 (&lt; 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 &lt; 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.</p>
</abstract>

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.

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

Mineralogia

This work is licensed under the Creative Commons Attribution 4.0 International License.

{"article-title":"Thorite inclusions in zircon of the monzogranite, Lower Nubia, SW Egypt"}

This report presents the results of a petrographical and mineralogical (optical microscopy, BSE-EDS image analysis) study of zircon in samples from the Lower...

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

Article Category: Original Paper

Published Online: Dec 19, 2023

Page range: 69 - 77

Received: Sep 15, 2023

Accepted: Nov 22, 2023

DOI: https://doi.org/10.2478/mipo-2023-0007

Keywords
Zircon, thorite, syngenetic inclusions, accessory minerals, metaluminous granite, Nubian Desert

© 2023 Kamaleldin M. Hassan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

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

Article Category: Original Paper

Published Online: Dec 19, 2023

Page range: 69 - 77

Received: Sep 15, 2023

Accepted: Nov 22, 2023

DOI: https://doi.org/10.2478/mipo-2023-0007

KeywordsZircon, thorite, syngenetic inclusions, accessory minerals, metaluminous granite, Nubian Desert

© 2023 Kamaleldin M. Hassan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
Zircon, thorite, syngenetic inclusions, accessory minerals, metaluminous granite, Nubian Desert