Petrogenetic implications of granitoids from the Eqat area, South Eastern Desert Egypt. | ||||
| Egyptian Journal of Geology | ||||
| Volume 69, Issue 1, 2025, Page 113-125 PDF (2.17 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/egjg.2025.372963.1110 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
Nahla Ahmed Shallaly   1; Mahmoud El Sayed El Mezayen2; Mohamed El-Sharkawi3; Ashraf El Azaab4
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| 1Geology Department, Faculty of Science, Cairo University | ||||
| 2Egyptian Mineral Resources Authority (EMRA) | ||||
| 3Geology Department, Faculty of Science, Cairo university | ||||
| 4Nuclear Material Authority | ||||
| Abstract | ||||
| The Eqat area is located in the Southern Eastern Desert near Shalateen Town. It comprises a thrust-fold belt of an ophiolitic mélange and an island arc metavolcano-sedimentary assemblage intruded by four magmatic bodies. Field relations and textural criteria indicate that these bodies belong to the syn-orogenic and post-orogenic granitoids widespread in the northern ANS. The syn-orogenic granitoids are exemplified by the Allaqi batholith to the west, which is composed of multiple coalesced plutons, and the Hoteib pluton to the north. Both which intrude the island arc assemblage and the ophiolitic mélange are of diorite/Qz diorite to tonalite composition and a gneissose fabric parallel to the foliation of the country rock. The post-orogenic granitoids are represented by the elongated Heleikonti batholith to the east and the Eqat plutons in the center of the area. These granitoids are composed of tonalite, granodiorite, and monzogranite, with an overall undeformed magmatic fabric. Textural criteria indicate that both groups are affected by local mylonitization along the Eqat shear zone, i.e., this shear zone postdates the magmatic processes. The recorded shear sense indicators in both groups highlight the sinistral sense of shear of the Eqat shear zone, which formed at greenschist facies conditions. Geochemically, these rocks are I-type, calc-alkaline to slightly alkaline, and of volcanic arc to within plate affinity, which was emplaced along a 20-30km thick crust. | ||||
| Keywords | ||||
| Petrography; Geochemistry; Volcanic arc granites; Eqat shear zone | ||||
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