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Accueil du site → Doctorat → Allemagne → Tectonogeomorphological and satellite image analysis of the Red Sea passive margin at the latitude of Wadi Siatin, Northern Quseir, Egypt.

Ludwig-Maximilians-Universität München (2014)

Tectonogeomorphological and satellite image analysis of the Red Sea passive margin at the latitude of Wadi Siatin, Northern Quseir, Egypt.

Elkhashab, Mohamed

Titre : Tectonogeomorphological and satellite image analysis of the Red Sea passive margin at the latitude of Wadi Siatin, Northern Quseir, Egypt.

Auteur : Elkhashab, Mohamed

Université de soutenance : Ludwig-Maximilians-Universität München

Grade : Doctoral thesis 2014

Résumé
Remote sensing has become an essential tool to improve data collection and spatial analysis in the geosciences. Identification of passive margin structures that are exposed along the Egyptian coast of the Red Sea, and their control on landforms has been hampered by limited data resolution and restricted access to this arid and inaccessible region. A major challenge lies in distinguishing features in the landscape that formed due to long-term tectonic activity and erosion from those features that modified the landscape recently. The goals of this

thesis were to determine to what degree the study area is currently tectonically active, and

what major hazards might affect the touristically developing coastal region.

This study deals with the structural and geomorphological evolution of the rift-related

structures and their impact on the sediment distribution and landforms variation in the northern Quseir area. In such a remote desert area, field and remote morphostructural analysis are needed to understand the structural and geomorphological evolution. The current study is mainly based on high-resolution QuickBird image analysis and field investigation. Field mapping was limited to one season, owing to acute safety concerns in the Eastern Desert. In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted, amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the Red Sea : the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are perfectly exposed as tilted fault blocks. The results of my field mapping and structural analysis show that the fault architecture of the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS- striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross faults as previously proposed in a neighboring area. Thus seismic activity is more likely to occur on the large NW-striking normal faults, leading to potentially larger Magnitude earthquakes than previously recognized in the area. The left-step may act as a barrier to rupture propagation and should be examined in more detail The northwestern Red Sea coast is part of the straight coastal segment that is generally characterized as seismically inactive. However, during the geological field mapping, I found evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces implies that at least some of the coastal uplift was seismogenic, because terraces of the same age can be found at different elevations along strike. Presumably, some of the seawarddipping,

Mots clés  : Tectonics, Remote Sensing, QuickBird, Red Sea, Egypt

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Page publiée le 29 septembre 2017, mise à jour le 7 octobre 2017