Tectonostratigraphy of the Ediacaran Fara formation of the central Oman mountains (Jabal Akhdar, Sultanate of Oman): implications for the late neoproterozoic evolution of the eastern Arabian plate

Abstract

In the western Jabal Akhdar Dome of northeastern Oman and within the Neoproterozoic Huqf Supergroup, well-exposed sedimentary formations span the Cryogenian to Ediacaran periods. These rocks bear the marks of the distant Cadomian Orogeny. Among these formations, the youngest corresponds to the diverse Ediacaran Fara Formation, partly time-equivalent to the Ara Group in the subsurface of Oman. Our study extensively examined the Fara Formation’s lithologies, stratigraphy, and syndepositional deformation features to shed light on the Late Ediacaran geological evolution of eastern Arabia. Through meticulous analysis, several key findings and confirmations of previous research emerged from our investigation: (1) the Fara Formation can be categorized into three distinct members (in ascending vertical succession FA1, FA2 and FA3); (2) while FA1 and FA2 members display signs of Cadomian D1 deformation, FA3 Member does not show any evidence of D1 deformation; (3) the first description of the fossil Palaeopascichnus assigns an Ediacaran age to the entire Fara Formation; (4) the volcaniclastic rocks within the Fara Formation are geochemically similar to Hormuz’s volcanics from the same period; and (5) carbonates and siliciclastic rocks of FA1 and FA2 formed within a probably NW/SE-striking back-arc basin associated with Cadomian subduction, while FA3′s siliciclastic rocks unconformably overlie the latter members.