A review of Mesozoic geodynamic evolution of the North Makran (SE Iran): A tale of a Neo-Tethyan ocean vanished due to two coexisting subduction zones

Abstract

This paper presents a synthesis of the geological features of each tectonic unit of the North Makran (SE Iran), integrating results of multidisciplinary analyses, including structural and stratigraphic studies, petrographic and geochemical analyses, thermobarometric studies, as well as biostratigraphic and geochronological dating. This wealth of data forms the basis for a novel geodynamic model of the Jurassic − Eocene evolution of the Neo-Tethys realm, which evolved between the Arabian Plate and the Lut Block. The features of the North Makran tectonic units support the existence of a mid-ocean ridge setting during the Jurassic – Early Cretaceous. Contrary to previous interpretations, the data from these tectonic units suggests a single oceanic basin separating the Arabian and Lut continental margins, without the interposition of a microcontinental block. In the Early Cretaceous, subduction initiation is recorded by volcanic arc assemblages accommodating the convergence between the Arabian Plate and Lut Block. The nucleation of an intra-oceanic subduction marked the separation of the North Makran Ocean from the Neo-Tethys. The Late Cretaceous was characterized by plume-related magmatism and the onset of the convergence in the North Makran Ocean, inducing its subduction beneath the Lut Block. This subduction is recorded by volcanic arc assemblage and high pressure and low-temperature metamorphism within a subduction complex. Meanwhile, intra-oceanic subduction persisted within the Neo-Tethys, accompanied by a subduction complex and arc magmatism. The final closure of the North Makran Ocean occurred during the Late Cretaceous –Late Paleocene with the progressive amalgamation of the two subduction complexes and the deformation of the interposing oceanic lithosphere. This study suggests that the subduction of a seamount chain in the North Makran Ocean played a key role in the shortening and closure of this basin. This research emphasizes the importance of considering multiple factors in understanding the tectonic evolution of the Neo-Tethys realm.