Provenance evolution from subduction to arc-continent collision: An example from Zagros–Makran Transition Zone

Arc-continent collision zones are critical areas where uplift, accretion, and erosion processes significantly influence the growth, elimination, or recycling of the continental crust. The Zagros–Makran Transition Zone, located along the Minab-Zendan Fault, represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards. Several tectonic slices, including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes, have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge. To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision, we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating, Hf isotopic values, and trace elements of detrital zircon grains. Our findings reveal a progressive scenario in which oceanic arc-related rocks of the ∼ 99 Ma Ganj Complex with Hf values ranging from +10 to +16 were uplifted during the Early to Late Eocene. The Eocene fore-arc sediments were sourced from the ∼ 49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between −5 and +12, as well as from the Ganj Complex. The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate. This led to a major sediment influx into the Makran trench with a detrital signal in the range ∼ 175–160 Ma with Hf isotopic values from −3 to +4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging ∼ 46–37 Ma and ca. 80 Ma. Notably, metamorphic lithic grains began to appear in the sediments in the Late Eocene. The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision. During the Late Oligocene–Early Miocene, detrital zircon ages in the range of ∼ 610–520 Ma, sourced from the Arabian basement, were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of ∼ 93 Ma with Hf isotopic values of +12 to +16. Following the development and uplift of the orogen from the Middle Miocene onward, detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc, Jurassic–Cretaceous Bajgan-Durkan Complex, and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.