Structural architecture and tectonic evolution of the Shabrawet Syrian Arc inverted zone at the Northern termination of the Gulf of Suez rift, Egypt

The present study offers a novel opportunity to characterize the structural style and tectonic evolution of the Mesozoic Shabrawet inverted structure zone and its interaction with the northward propagation of the Gulf of Suez rift, Egypt. Based on the integration of fieldwork, detailed surface mapping and subsurface imaging by borehole data and seismic interpretation, the geology of Shabrawet area is characterized into the northern, central, and southern structural subareas. The central subarea has exposures of Cretaceous rocks whereas the northern subarea has the Jurassic/Cretaceous subcrop capped by the Oligo/Miocene rocks with remarkable stratigraphic hiatus probably due to differential erosion or non-deposition of the Lower Tertiary-Cretaceous sediments. The southern subarea represents a SW-dipped gulf-parallel block of Middle/Late Eocene and Oligo/Miocene sediments. The structural elements of the Shabrawet area are represented by a group of plunging and double plunging folds of NE-ENE-, E-W, WNW- trends that are dissected by NE-reverse faults, ENE-trending transpressional faults, N-S sinistral faults, E-W to WNW – trending dextral faults and NW-trending normal faults. Structural analysis, fault slip data, and the constructed subsurface seismic profiles and thickness maps reveal the tectonic history of the area through a Late Cretaceous-Eocene transpressional inversion of E to ENE-extensional Jurassic border faults. This ENE-inverted Syrian arc structure zone played as structural high with non-deposition of Eocene sediments and differential erosion of Cretaceous sediments. During the Oligo-Miocene NE-extension, this high-oblique inverted zone terminates the northward propagation of gulf parallel faults and SW- block rotation of the northern structural province of the Gulf of Suez rift at the southern subarea and the central Bitter Lake. Further westward, this ENE-inverted Shabrawet-Abu Sultan intrabasinal Jurrassic half-graben of N- dipping might be structucturally correlatable with the NE- inverted structural belt of Gebel Maghara in Northern Sinai.

本研究为刻画埃及中生代沙布拉维特（Shabrawet）反转构造带的构造样式与构造演化，及其与苏伊士裂谷（Gulf of Suez rift）北向扩展的相互作用提供了全新契机。
本研究整合野外调查、详细地表填图，以及钻孔数据（borehole data）与地震解释（seismic interpretation）开展的地下成像工作，将沙布拉维特地区地质划分为北、中、南三个构造亚区。其中中部亚区出露白垩系（Cretaceous）地层；北部亚区发育侏罗系/白垩系潜露头，其上被渐新统/中新统（Oligo/Miocene）地层覆盖，存在显著的沉积间断（stratigraphic hiatus），该间断大概率由下第三系-白垩系沉积物的差异侵蚀（differential erosion）或沉积缺失（non-deposition）所致。南部亚区为一条平行于海湾、向西南倾斜的断块，发育中始新统/晚始新统与渐新统/中新统沉积物。
沙布拉维特地区的构造形迹表现为一系列呈北东-北东东（NE-ENE）、东西向（E-W）、西西北向（WNW）展布的倾伏褶皱（plunging fold）与双倾伏褶皱（double plunging fold），这些构造被多组断层切割：北东向逆断层（reverse fault）、北东东向压扭断层（transpressional fault）、南北向左旋断层（sinistral faults）、东西向至西西北向右旋断层（dextral faults），以及北西向正断层（normal faults）。
构造解析、断层滑动数据（fault slip data），以及构建的地下地震剖面（seismic profiles）与厚度图（thickness maps）揭示了该地区的构造演化历史：晚白垩世-始新世时期，东西向至北东东向伸展的侏罗系（Jurassic）边界断层发生了压扭反转。该北东东向反转的叙利亚弧（Syrian arc）构造带曾作为构造高地（structural high），导致始新统沉积物发生沉积缺失，并对白垩系地层产生差异侵蚀。
在渐新世-中新世北东向伸展阶段，该高倾斜反转带终止了平行于海湾断层的北向扩展，以及苏伊士裂谷北部构造区在南部亚区与中部苦湖（Bitter Lake）处的西南向断块旋转。
继续向西延伸，该北东东向反转的沙布拉维特-阿布苏丹盆内侏罗系向北倾斜半地堑（half-graben），在构造上可与西奈北部的马格拉山（Gebel Maghara）北东向反转构造带进行对比。