Utilizing remote sensing and field data for geological mapping and polyphase deformation analysis of Um Laseifa ophiolites, Eastern Desert, Egypt

The Wadi Um Laseifa area, located in the Central Eastern Desert of Egypt, encompasses a range of Neoproterozoic rock units, including ophiolitic mélange, island arc assemblage, and granitic intrusions as well as Miocene clastic deposits. The current research attempts to analyze the structural and lithological characteristics of this area by integrating data from multisource remote sensing (Sentinel 2, Planetscope and hyperspectral PRISMA), along with field and structural relationships, geometrical analysis of structural readings, and petrographic studies. Applying various techniques of remote sensing, such as false color composite (FCC), principal component analysis (PCA), and Minimum noise fraction (MNF), enabled the identification of the structural features over various scales besides accurate lithological discrimination. Data analyses have discriminated the intricate Neoproterozoic rocks into ophiolitic mélange that includes serpentinites, meta-pyroxenites, metagabbro, chert and mélange matrix, island arc assemblage comprising metavolcanics, metavolcano-sedimentary rocks and hornblende schist, and monzogranite and granodiorite intrusions. These rocks have been affected by a thrust stack of three major faults striking NW-SE to NNW-SSE and dipping steeply to the SW. There are two prominent folds represented by a major anticline affecting the island arc metavolcano-sedimentary rocks and a major syncline affecting the ophiolitic rocks. Both folds possess axial planes striking NW-SE and gently plunging NW fold axes. The area is also intersected by E-W or ENE-WSW strike-slip faults, along with major NW-SE normal faults that controlled the distribution of the Miocene clastic deposits. Geometrical analysis has identified three ductile deformation phases: D₁ is marked by NW-SE isoclinal folds; D₂ produced NW-SE major folds and thrust faults that are coaxial with D₁; and D₃ led to the formation of NE-SW open folds. The multisource remote sensing analysis that has been carried out in this work illustrated the efficacy of the employed methodology in conducting thorough geological analyses and strongly advocates for its application in analogous studies in arid environments.