Neoproterozoic Tectonic Events of Egypt

• 作者: Mohamed ABD EL-WAHED Zakaria HAMIMI
• 来源期刊: 地质学报（英文版）
• 年，卷（期）: 2021,（4）
• 所属期刊栏目: REVIEWS
• 页码范围: 1366-1405
• 页数: 40页
• 语种: 英文

摘要

The Egyptian Nubian Shield(ENS)represents the northwestern part of the Arabian-Nubian Shield and the northern extension of the East African Orogen.The ENS is regarded as being formed due to northward-directed escape tectonics.It is characterized by mild accretion and suture zones dominated by major strike-slip zones with a commonly sinistral sense of movement;some shear zones display a dextral sense of shear.It is dominated by gneisses and migmatites in the south,arc volcaniclastic metasediments and highly dismembered ophiolites in the central parts,whereas its northern part is dominated by late-to post-tectonic granitoids.In southern Sinai,the Neoproterozoic rocks are grouped into four complexes,namely Feiran-Solaf,Sa'al-Zaghra,Kid and Taba.The ENS ophiolites were formed between 730-750 Ma,mainly in a supra-subduction zone setting.The ENS has undergone a Neoproterozoic deformation history involving three successive phases:(1)Early N-S shortening phase(D1),(2)Syn-accretionary phase(D2)and(3)Post-accretionary phase(D3).The initial island-arc stage(780-730 Ma)is a N-S shortening phase initiated by collision between the Eastern Desert tectonic terrane to the north with both the Gebeit and Gabgaba terranes to the south(830-720 Ma).During the arc-splitting and back-arc spreading stage(730-620),voluminous syn-tectonic granitoids intruded into the ENS(750-610 Ma).The E-W-directed compressional/transpressional phase(620-450 Ma)led to the overall uplift of the central part of the ENS and consequently the development and exhumation of the core complexes in oblique convergent zones.The E-W intense shortening deformation resulted also in the formation of NW-and NE-striking sinistral and dextral strike-slip shear zones,respectively.The latest periods of the E-W-directed compressional/transpressional regime were characterized by deposition of the molasse-type Hammamat Sediments unconformably over the Dokhan Volcanics,or interbedded with them.The combined thrusting,folding and sinistral-reverse shearing structures have been interpreted to resulted from the E-W-directed compressional/transpressional phase in response to the oblique shortening of the Arabian-Nubian Shield between East and West Gondwana.