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This research investigates the mineral chemistry and origins of distinct granitoid phases in the Nubian Shield.

January 14, 2026Geosciences0 citationsOpen Access

Mineral Chemistry, Whole-Rock Characterization, and EnMap Hyperspectral Data Analysis of Granitic Rocks of the Nubian Shield: A Case Study from Suwayqat El-Arsha District, Central Eastern Desert, Egypt

AAAhmed M. Abdel-RahmanAl-Azhar University BABassam A. Abuamarah ASAli SheblUniversity of Debrecen

Key Points

This research investigates the mineral chemistry and origins of distinct granitoid phases in the Nubian Shield.
Characterization of granitoids including I-type granodiorite and A-type monzogranite
Use of EnMAP hyperspectral data for spectral analysis and discrimination of granitoid types
Application of the Sequential Maximum Angle Convex Cone (SMACC) method
Both granite types show evidence of fractional crystallization affecting minerals such as alkali feldspar.
Granitic rocks exhibit distinct chemical compositions with varying SiO2 and K2O levels.
Analysis indicates potential geological settings for the formation of the granitoids.

Abstract

Gabal (G.) Suwayqat El-Arsha contains two distinct phases of granitoids: I-type granodiorite and A-type monzogranite. Both of them experienced intense fractional crystallization that affected plagioclase, alkali feldspar, quartz, and, to a lesser degree, ferromagnesian minerals. EnMAP hyperspectral data were used to discriminate between the different granitoid types through spectral analysis, using various techniques, including the Sequential Maximum Angle Convex Cone (SMACC) method. Granodiorite has high SiO2 (68.21–71.44 wt%), Al2O3 (14.29–14.92 wt%), Fe2O3 (1.99–3.32 wt%), and CaO (2.34–3.87 wt%), whereas monzogranite has even higher SiO2 (73.58–75.87 wt%) and K2O (4.28–4.88 wt%). Both granodiorite and monzogranite exhibit calc-alkaline, peraluminous to metaluminous, and medium- to high-K characteristics, with attendant enrichment of light REE and LILE and depletion of heavy REE and HFSE. A negative Eu anomaly may indicate early plagioclase fractionation, especially in the monzogranite. The I-type granodiorite is likely derived from a high-K, mafic protolith that partially melted during lithospheric delamination, leading to severe fractional crystallization in the upper crust in a post-collisional environment. In contrast, the monzogranite exhibits A-type characteristics and was likely emplaced in an anorogenic setting. Both granites were affected by several episodes of hydrothermal alteration, resulting in silicification, kaolinitization, sericitization, and chloritization. The intrusions studied here exhibit key similarities with those in the Wadi El-Hima area, including tectonic setting, petrogenetic type, Neoproterozoic age (Stage I collisional: ca. 650–620 Ma; Stage II post-collisional: ca. 630–590 Ma), and mineralogical assemblages (notably two-mica granites). These correlations suggest that both suites form part of a regionally extensive batholith composed of I- and A-type granites, stretching from north of the Marsa Alam Road (Umm Salatit–Homrit Waggat) southward to at least Wadi El-Hima.

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