The geodynamic history of east-central Iran during the Early Jurassic from the sedimentary records in the aftermath of the main Cimmerian orogeny

An integrated sedimentological and stratigraphic study of the Ab-Haji Formation is crucial for palaeogeographic reconstructions of central Iran because it reflects the geodynamic history of the region during and in the aftermath of the main Cimmerian event (Triassic–Jurassic boundary to Liassic). We measured and studied seven well-exposed outcrop sections in order to identify lithofacies and facies associations and to interpret the palaeoenvironment. Six facies associations are recognized: Fluvial plain, coastal plain, delta plain, delta front, prodelta, and shallow siliciclastic shelf. Reconstruction of the palaeogeography of east-central Iran shows a west-to-east and northwest-to-southeast continental-to-marine gradient. Based on thickness variations, lateral facies changes, palaeocurrent patterns, and changes in the nature of the basal contact of the Ab-Haji Formation on the Yazd, Tabas, and Lut blocks, the source of siliciclastic material was likely the fault-bounded Yazd Block in the west and the Shotori Swell at the eastern edge of the Tabas Block. The pattern of thickness variations, rapid east−west facies changes, and provenance is best explained by a tectonic model invoking large tilted fault blocks in an extensional basin.