Regional joint sets in the Arabian Platform as indicators of intraplate processes

Abstract

The eastern part of the Saudi Arabian craton is a platform underlain by gently tilted and horizontal Mesozoic‐Cenozoic sedimentary rocks everywhere more than 250 km distant from the Zagros deformation front. Despite its tectonic simplicity, the platform contains several laterally extensive, but subdued, structures and lineaments belonging to more than one system of fault zones and flexures. New microtectonic observations of dominant sets of extension and conjugate hybrid joints permit regionally significant extension directions to be inferred and the origin of the macrostructures to be assessed. The central Arabian arch, the E‐W crest of which coincides with an axis of Mesozoic subsidence, developed during the Late Cretaceous to Eocene when the basin inverted as a consequence of the emplacement of ophiolite‐bearing nappes on the Zagros and Oman margins. During arching, there was strike‐parallel elongation of beds. At the same time as the arch amplified, the central Arabian graben system evolved as a result of the northward displacement of an East Arabian block or sheet that became detached across an arcuate separation zone, which in the south is coincident with the crest of the arch. An important Neogene response in the Arabian platform to NE‐SW shortening in the Zagros ranges was the formation of a swarm of NE striking master joints and lineaments. These structures reflect the diffuse and peripheral expansion of the foreland beyond the Zagros deformation front.