Temporal and thermal evolution of extensional faulting in the central Gulf of Suez and detrital zircon (U-Th)/He constraints on the thermo-tectonic Paleozoic and Mesozoic history of the Sinai, Egypt

Abstract

Many fundamental concepts of rifting have been influenced by observation made in the Gulf of Suez as a result of detailed structural and sedimentological studies. Although the three-dimensional structural geometry of the rift is well understood, the timing of faulting, the nature of faults linkage during progressive rifting and the influence on syn-rift sedimentation is poorly constrained. Despite ample fission track data from the Sinai rift flank, the lack of thermochronometric data from exhumed pre-rift sedimentary cover and crystalline basement blocks in a proper structural context within the rift limit the temporal and thermal reconstruction and the influence of pre-rift structures on the style of rifting. To elucidate the temporal and spatial evolution of extensional faulting and fault interaction in the central Gulf of Suez, this study presents new apatite (U-Th)/He (AHe) thermochronometric data from vertical transects and combines both surface and borehole sample arrays from normal fault blocks, integrated with structural block reconstruction of the central east margin of the Gulf of Suez. AHe data from the Sinai border fault complex at Gebel Samra (north) and Gebel Mutga (south) and surface and subsurface samples from the Hamman Faraun fault blocks explore the temporal progression of normal faulting and the evolution of fault hard linkage in the central Gulf of Suez in the early to middle Miocene after the onset of normal faulting at ~23 Ma. As a second aspect, zircon (U-Th)/He (ZHe) dating from pre-rift strata and basement samples were analyzed to better constrain the pre-Tertiary tectonic, detrital provenance and thermal evolution of the Gulf of Suez to shed light on the Paleozoic/Mesozoic tectonic evolution and its influence on Red Sea-Gulf of Suez rifting. ZHe data from pre-rift strata in the central Gulf of Suez record a detailed Paleozoic/Mesozoic tectonic history that is highly influenced by Carboniferous, Triassic/Jurassic, and Santonian tectonism. Carboniferous Abu Thora sandstone contain detrital ZHe ages that suggest very short lag time, indicative of late Paleozoic tectonism and rapid cooling. Similarly, Triassic Qiseib sandstones, exhibits detrital ZHe ages indistinguishable from its stratigraphic age, underlining the importance of Triassic/Jurassic Neo-Tethyan rifting. Cretaceous Matulla pre-rift sandstones are dominated by Santonian detrital ZHe ages, with very short lag times, associated with the Syrian arc inverted structures and folding. The combination of AHe and ZHe ages in a detailed stratigraphic and structural context elucidates both the Neogene Gulf of Suez rift evolution and the impact of Paleozoic/Mesozoic tectonism on the structural grain of the gulf allowing for a more detailed and spatially differentiated understanding of the timing of extensional faulting and nature of fault linkage during progressive early to middle Miocene rifting in the central Gulf of Suez.