The Tectonic Map and Structural Provinces of the Late Neoproterozoic Egyptian Nubian Shield: Implications for Crustal Growth of the Arabian–Nubian Shield (East African Orogen)

Abstract

The Late Neoproterozoic Egyptian Nubian Shield (ENS) has attracted increasing attention since the establishment of the Egyptian Geological Survey and Mining Authority (EGSMA (1896)), which conducted the first mapping. In the last three decades, rapid improvements in analytical techniques, along with field-oriented studies, have made it possible for the interpretation of the ENS as an integral part of the juvenile Arabian–Nubian Shield (ANS) as a portion of the East African Orogen (EAO). However, a consistent tectonic map of the ENS does not exist. Presentation of such a map is the main objective of the present work where Landsat-based lithological discrimination is combined with the systematic structural investigation and careful reassessment of previously published geological maps. Our interpretation of this map indicates that in accordance with previous work, the basement units of the Eastern Desert (ED) can be divided into three structural domains: Northern, Central, and South-Eastern Desert provinces. The proposed provinces are ascribed to three different plate tectonic far-field boundary conditions. The earliest magmatic, metamorphic, and tectonic history was set off by the approximate north–south convergence of the Gabgaba-Gebeit, Jiddah-Asir terranes, and Eastern Desert-Midyan terranes along the Yanbo-Onib-Sol-Hamid-Gerf-Allaqi-Heiani (YOSHGAH) suture between c. 800 and 620 Ma. The second event between c. 640 and 580 Ma was correlated with the Nabitah Orogeny when the Ad Dawadimi-Ar Rayn terranes in the eastern Arabian Shield accreted to the earlier consolidated arc terranes (Afif and Tathlith terranes). During this period, east–west convergence between northwestern Saudi Arabia and the Central Eastern Desert (CED) in Egypt caused a pronounced strike-slip deformation associated with the displacement along the wider Najd Fault system. The third orogenic phase, which was younger than c. 580 Ma, was controlled by the evolution and retreat of the Cadomian Arc. The northern portions of the ENS and the northern Arabian Shield experienced extension whereas extensive post-orogenic magmatism was related to mantle delamination and associated crustal thinning.

Structural mapping and kinematic history of the Qena-Safaga Shear Zone (Egyptian Nubian Shield, East African Orogen)

“…Such structural and tectonic setting advocates a complex tectonic history characterized by interplay of extensional and transtensional tectonic regimes. The obtained results here support the results obtained by [30][31] concerning the structural and tectonic setting of the NED. In [29] the NED was referred to as an extensional province characterized by extensional faults and dyke swarms, and ascribed to the retreating of the Cadomian arc in Late Neoproterozoic-Cambrian time (Fig.…”

Large-scale geological structures of the Egyptian Nubian Shield

“…The general consensus that the ENS is liable to subdivision into three structural domains (North Eastern Desert, NED; Central Eastern Desert, CED; South Eastern Desert, SED) [12][13][14] was merely premised on the conspicuous differences in basement lithology with little (if any) contribution to the ubiquitous changes of "internal" characteristic structures. The characteristic lithology of NED is the huge amount of granitod intrusions, and Dokhan Volcanics and Hammamat sediments, together with few exposures of island arc rocks (Fig.…”

“…Although the two-tier "suprastructure-infrastructure" orogenic model 17,18 and the previously mentioned threefold classification of the ENS into three structural provinces have widely accepted, claim for further studies based on geophysical methods (seismic, gravity and magnetic) in order to detect the major subsurface tectonic features and to explore the surface structures with depth is highly recommended 19 . In addition, recent comprehensive regional structural/tectonic studies and associated isotopic data 14,[18][19][20][21][22][23] have contributed to the structural setting and tectonic evolution of the ANS and ENS, as well as they encourage new reliable approaches for deciphering the problematic issues and examine the validity of the applied models. In this context, the present study is the first attempt to intigrate structural and potential data (gravity and magnetic) for deciphering the large-scale structures of the Pan-African belt in the ENS.…”

Remote Sensing-Based Lithological Mapping of the Qena-Safaga Shear Zone Juxtaposing Northern and Central Tectonic Provinces of The Egyptian Nubian Shield

“…The tripartite classification of the Eastern Desert [1][2][3] subdivided the Egyptian Nubian Shield in the Egyptian Eastern Desert into three tectonic terranes based on their lithological and structural variations, where the boundaries between these terranes are marked by megashears. Accordingly, the Eastern Desert was classified into North Eastern Desert (NED), Central Eastern Desert (CED) and South Eastern Desert (SED).…”

“…As a consequence, mapping of a large area as such introduced in the present study hasn't been considered before. The main aim of the present study is to update the geological map of the study area which is regarded as a transition zone between wrench-related tectonics in the CED to extensional tectonic regime in the NED [3].…”