Early Jurassic Rifting of the Arabian Passive Continental Margin of the Neo-Tethys. Field Evidence From the Lurestan Region of the Zagros Fold-and-Thrust Belt, Iran

The Arabian passive margin formed at the southern margin of the Neo-Tethys ocean during the breakup of Pangea. In the Lurestan region of the Zagros mountain belt, the deformed Arabian continental paleo-margin can be reconstructed as originally consisting of distinct crustal domains, including a proximal sector and a distal continental ribbon, separated by a deep-water trough, known as the Radiolarite Basin. Such an architecture was shaped by the continental rifting process, thus reflecting timing and style of continent separation, which is generally assumed to have occurred during the Permo-Triassic interval. This study reports evidence of syn-sedimentary extensional faults, unconformities, and facies changes in the Mesozoic stratigraphic succession of the Lurestan region, which point to a major Jurassic extensional pulse. In detail, extension reached its climax at the end of the Early Jurassic, when tectonically driven drowning of the long-lived Triassic to Early Jurassic carbonate platform led to the transition from shallow- to deep-water environments in large areas of the inner margin, coevally with the development of the Radiolarite Basin. Our findings suggest a two-step continental rifting in this area, with the first Permo-Triassic phase predating an Early Jurassic one.