The village of As Sifah, well known for being the only area in Oman where rare high-pressure, low-temperature metamorphic rocks from the blueschist and eclogite facies occur, presents a unique opportunity to study the processes that buried them deep within the Earth’s mantle, then exhumed them back onto the surface. Here, the geologic structures and geometry are analyzed at the outcrop, hand sample, and thin section scales in order to constrain the nature of their movement and tectonic environmental history. This allows for interpretation of the tectonic evolution of the area as well as providing supporting evidence for the more feasible tectonic model in existing debates. The results indicate that the rocks here underwent two instances of deformation: the first being associated with structures exhibiting a past flattening movement, and the second being associated with structures exhibiting a later, likely unstable, constrictional and non-coaxial movement. This, combined with directional data that was collected, fortifies the model where (1) the continental crust of the Arabian plate, was buried underneath oceanic crust in a ~NE direction concurrent with the obduction of the famous Semail Ophiolite onto the continental margin during the late Cretaceous; and (2) the rocks were rapidly expelled from the mantle around the end Cretaceous during the same subduction event, resulting in the formation of fold thrust sheets.
Dr. Chuck Bailey
Carpenter, Nick, "Structural Analysis of Blueschists and Eclogites at As Sifah, Oman" (2022). Geology Senior Theses. William & Mary. Paper 22.
Available for download on Thursday, May 18, 2023