The Structural Evolution of the Hamisana Geodynamic Zone, Red Sea Region, NE Sudan
Abdalla E. M. Elsheikh, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
Khalid A. Elsayed Zeinelabdein, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
Elsheikh M. Abdel Rahman, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
Musab A. Eljah, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
The study area lies in the Red Sea region of NE Sudan, which belongs to the Nubian Shield that originated during the Pan African Era. The Hamisana Shear Zone (HSZ) is a broad zone of cataclastic deformation in the Nubian Shield formed as prominent N-S trending major structure. The objective of this work is to recognize the structural manifestations through the remotely sensed data and field measurements for demarcation of the major structural styles and to study the structural evolution of the study area with respect to the tectonic events of the Nubian-Arabian Shield in NE Sudan. A set of four Landsat 7 ETM+ scenes (p172r45, p172r46, p173r45 and p173r46) has been mosaicked and subset to obtain a full coverage of the study area. Remote sensing data were supplemented by field observations and intense structural measurements. Ductile deformation has been obtained in macro- and meso-scales under different folding styles representing different deformation phases. In Landsat imagery, many folds are observed; where the N-S trending fold is the common folding direction, however, the NE-SW, NW-SE and E-W folding directions are also defined. The common types of faults in the study area are strike slip faults, where the dextral sense of movements is dominant. The extensional fractures are parallel to the greatest stress axis (σ1) in NW-SE direction, the release fractures are in NE-SW normal to the acting stress (σ3), where the shear fractures are in N-S and ENE direction parallel to the positive and negative shear arms (σ2s±), respectively. At least three episodes of tectonic events involving five phases of deformations are recognized. The first episode is represented by the formation of foliation (D1), followed by the strong collision between Haya and Gebeit terrains (D2) resulted in tight folding. The second episode is the collision of the mentioned arcs with Gabgaba terrain (D3). The third episode is represented by the open folding with E-W axis, and the reactivation of the N-S shear zone in the study area (HSZ) that represents the prominent structural feature in the area. The former HSZ represents a geodynamic zone, hereafter referred to as the Hamisana Geodynamic Zone (HGZ). This is evident by the crustal shortening, the presence of ophiolitic masses with the eastward younging of its lithologies opposite to the thrust direction. The intensive N-S shearing marks a significant cataclastic deformation.
Structural Styles, Structural Evolution, Nubian-Arabian Shield, Hamisana Area, Red Sea Region, Sudan
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