ABSTRACT The study examines the Egyptian Red Sea shelf and throws more light on the structural set‐up and tectonics controlling the general framework of the area and nature of the crust. Herein, an integrated study using gravity and magnetic data with the available seismic reflection lines and wells information was carried out along the offshore area. The Bouguer and reduced‐to‐pole aeromagnetic maps were processed and reinterpreted in terms of rifting and plate tectonics. The qualitative interpretation shows that the offshore area is characterized by positive gravity everywhere that extremely increases towards the centre of the graben, supporting the presence of an intrusive zone below the axial/main trough. The gravity data were confirmed by the presence of high magnetic amplitudes, magnetic linearity and several dipoles concentrated along the rift axis for at least 250 km. The lineament analysis indicates widespread of the Erythrean (Red Sea) trend that was offset/cut by transform faults in the NE direction (Aqaba). The tectonic model suggests the presence of one tensional (N65°E) and two compressional (N15°W, N30°W) phases of tectonism, resulted in six cycles of deformations, classified into three left lateral (N35°E, N15°E and N–S) and three right lateral (N85°W, N45°W and N60°W). The basement relief map reveals a rough basement surface that varies in depth between 1 and 5.6 km. It outlines several offshore basins, separated from each other by ridges. The models show that the basement consists of tilted fault blocks, which vary greatly in depth and composition and slopes generally to the west. They indicate that the coastal plain is underlain by acidic basement blocks (continental crust) with no igneous activity while suggesting elevated basic materials (oceanic crust) below the rift axis. The study suggests that northern Red Sea forms an early stage of seafloor spreading or at least moved past the late stage of continental rifting.

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使用地球物理数据对埃及红海陆架地质学的新贡献

摘要 该研究考察了埃及红海陆架，并进一步阐明了控制该地区总体框架和地壳性质的结构设置和构造。在此，利用重力和磁力数据以及可用的地震反射线和井信息沿近海区域进行了综合研究。根据裂谷构造和板块构造对布格和减极航磁图进行了处理和重新解释。定性解释表明，近海区域的特征是处处为正重力，向地堑中心急剧增加，支持轴向/主槽下方存在侵入带。重力数据被高磁振幅的存在所证实，磁线性和几个偶极子沿裂谷轴集中至少 250 公里。线性分析表明，被 NE 方向（亚喀巴）的转换断层偏移/切割的 Erythrean（红海）趋势普遍存在。构造模型表明存在一个拉力（N65°E）和两个挤压（N15°W，N30°W）阶段的构造运动，导致六个变形周期，分为三个左侧（N35°E，N15°E）和 N–S）和三个右侧（N85°W、N45°W 和 N60°W）。地下室地形图显示了一个粗糙的地下室表面，其深度在 1 到 5.6 公里之间。它勾勒出几个近海盆地，由山脊彼此隔开。模型表明，基底由倾斜的断块组成，其深度和成分变化很大，坡度通常向西倾斜。他们表明沿海平原的下方是没有火成岩活动的酸性基底块（大陆地壳），同时表明裂谷轴以下的碱性物质（洋壳）升高。该研究表明，红海北部形成了海底扩张的早期阶段，或者至少已经超过了大陆裂谷的晚期阶段。