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<p>This study provides a comprehensive analysis of the large-scale north-south (N-S) shear zones in the Egyptian Nubian Shield (ENS), a critical segment of the East African Orogen. Integrating aeromagnetic, gravity, remote sensing, and field-based structural data, the study delineates the geometry, kinematics, and tectonic significance of these N-S shear zones and their interaction with other major tectonic features, such as the Najd Fault System and the Keraf suture. The ENS is subdivided into compressional, transpressional, and extensional domains, each characterized by distinct structural regimes and evolutionary histories. Within the Central Transpressional Domain, the Najd Fault System (NFS) creates a complex network of NW-SE-trending sinistral strike-slip shear zones intersected by NE-SW-directed dextral shear zones, forming a conjugate shear system. Key large-scale N-S-trending shear zones in the ENS include the Safaga-Shalul, Wadi Kareim-Umm Bisilla, Um Gheig-Nugrus, Barramiya-Mueilha, Abu Swayel-Muqsim, and Himitrah-Madari shear zones. The structural evolution of the ENS comprises five main deformational phases. D1 features N-S shortening, resulting in thrust imbrication and E-W-trending foliations. D2 is marked by NE-SW-directed shortening and NW-trending sinistral shearing, characterized by large-scale sinistral shear zones. The Najd Fault System (620-540&#xa0;Ma) dominates the Central Transpressional Domain. D3 is characterized by E-W shortening and N-S dextral shearing, leading to the formation of N-S transpressional shear zones and folds (600-590&#xa0;Ma) that affect all rock units except post-tectonic granites. D4 features N-S-oriented dextral shear zones that affect E-W, NW-SE, and N-S structural fabrics within transpressional belts. Red Sea rifting reactivated these zones, transforming them into brittle, sinistral strike-slip faults that affect all rock units. The NW-SE, N-S, and NE-SW-oriented shear zones in the ENS form a conjugate system linked to the activity of the Najd Fault System. Geophysical data indicate that these shear zones likely extend subsurface, connecting to the extensive N-S-striking shear zones in the Nubian Shield. The Keraf shear zone developed contemporaneously with the NFS, suggesting a link to the genesis of the N-S dextral shear zones.</p>

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Characterization of newly identified N–S shear zones in the Egyptian Nubian Shield by integrating geophysical, remote sensing and field data

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  • 发表日期：

    2026年5月25日

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  • Mohamed A. Abd El‑Wahed,
  • Ahmed M. Eldosouky

摘要

This study provides a comprehensive analysis of the large-scale north-south (N-S) shear zones in the Egyptian Nubian Shield (ENS), a critical segment of the East African Orogen. Integrating aeromagnetic, gravity, remote sensing, and field-based structural data, the study delineates the geometry, kinematics, and tectonic significance of these N-S shear zones and their interaction with other major tectonic features, such as the Najd Fault System and the Keraf suture. The ENS is subdivided into compressional, transpressional, and extensional domains, each characterized by distinct structural regimes and evolutionary histories. Within the Central Transpressional Domain, the Najd Fault System (NFS) creates a complex network of NW-SE-trending sinistral strike-slip shear zones intersected by NE-SW-directed dextral shear zones, forming a conjugate shear system. Key large-scale N-S-trending shear zones in the ENS include the Safaga-Shalul, Wadi Kareim-Umm Bisilla, Um Gheig-Nugrus, Barramiya-Mueilha, Abu Swayel-Muqsim, and Himitrah-Madari shear zones. The structural evolution of the ENS comprises five main deformational phases. D1 features N-S shortening, resulting in thrust imbrication and E-W-trending foliations. D2 is marked by NE-SW-directed shortening and NW-trending sinistral shearing, characterized by large-scale sinistral shear zones. The Najd Fault System (620-540 Ma) dominates the Central Transpressional Domain. D3 is characterized by E-W shortening and N-S dextral shearing, leading to the formation of N-S transpressional shear zones and folds (600-590 Ma) that affect all rock units except post-tectonic granites. D4 features N-S-oriented dextral shear zones that affect E-W, NW-SE, and N-S structural fabrics within transpressional belts. Red Sea rifting reactivated these zones, transforming them into brittle, sinistral strike-slip faults that affect all rock units. The NW-SE, N-S, and NE-SW-oriented shear zones in the ENS form a conjugate system linked to the activity of the Najd Fault System. Geophysical data indicate that these shear zones likely extend subsurface, connecting to the extensive N-S-striking shear zones in the Nubian Shield. The Keraf shear zone developed contemporaneously with the NFS, suggesting a link to the genesis of the N-S dextral shear zones.