Provenance evolution of Oligocene—Pliocene foreland deposits in the Dezful embayment to constrain Central Zagros exhumation history

This paper presents a detailed provenance analysis of the 6.5-km thick Oligocene—Pliocene foreland succession in the north Dezful embayment in Zagros, Iran. Using petrography, geochemistry, and paleoflow analysis, we determined three provenance shifts during the exhumation of Zagros orogen. Above the Ahwaz sandstones, sourced from the Arabian craton, a sharp decrease in SiO₂/Al₂O₃, Zr/Sc, Th/Sc, Th/Co and Th/Cr within the Gachsaran Fm., and the appearance of first-cycle sands derived from metamorphic and volcanic rocks at the base of Aghajari Fm., characterize the onset of exhumation, rising topography and denudation of the Zagros orogenic system during latest Oligocene and constitute the first shift. The second shift, in middle Aghajari Fm., is marked by a distinct increase in radiolarian cherts and compatible/incompatible elements, indicating the exhumation of Neo-Tethyan radiolarite ophiolite allochthonous slices in the High Zagros Zone during Tortonian (~9 Ma). A vast number of carbonates derived from nearby growing Izeh Zone anticlines characterize the Messinian (~7 Ma) Bakhtyari conglomerates marking the third shift. In conclusion, a detailed hands-on provenance analysis of the clastic sedimentary sequences in the north Dezful embayment enabled us to determine catchment areas and shifts hitherto unstudied thus contributing to the exhumation history of the Central Zagros orogenic system.