Strain Analysis and Microstructural Investigation of the Jabal Tays Ophiolite Complex, Eastern Arabian Shield, Saudi Arabia

Abstract

The present study deals with the Jabal Tays ophiolite area, which was affected by Al Amar-Idsas fault. It is one of the most important tectonic features in the Eastern Arabian Shield. This study aims to accomplish through field investigation, finite strain and microstructural analysis for understanding the nature of tectonic evolution and the deformation in the Jabal Tays area. Field and microscopic investigations indicate that mafic-ultramafic rocks at Jabal Tays include the large amount of serpentinite, subordinate amounts of gabbro intruded by mafic dikes, mélange, serpentinite schist, and listwaenite. The serpentinite makes up the bulk of Jabal Tays, is variably sheared and typically consists of relatively massive serpentinite cut by shear zones marked by serpentinite schist. Based on finite strain and microstructural analysis, mafic-ultramafic rocks in the Jabal Tays area are generally confined to brittle-ductile shear zones, which they are sub-parallel to the prevailing NW or NNW structural trends. It is confined mainly to the metamorphic terrains, especially to zones intruded by mafic volcanic rocks. It is concluded that the contacts between the Abt schist and metavolcano-sedimentary rocks were formed during progressive thrusting under brittle to semi-ductile deformation conditions by simple shear that also involved a component of vertical shortening, causing subhorizontal foliation in the Jabal Tays area.