Kinematic Reconstruction of the Central Tethysides: A major extrusion system of the Tethyan Orogen

The region including Iran and Afghanistan constitutes the central part of the Tethyan palaeogeographic domain. Its first-order architecture is defined by continental fragments that are separated from Eurasia by a Triassic suture zone (remains of the Palaeo-Tethys), and by a Cenozoic suture with Mesozoic oceanic rocks (remains of the Neo-Tethys). Along-strike heterogeneity resulting from strain partitioning subdivides the Tethyan system into three segments, from west to east: the Mediterranean, Iranian-Afghan, and Tibetan domains.

Our reconstruction shows that the Central Tethysides share key tectonic elements with the widely studied Mediterranean and Tibetan orogenic systems, while placing particular emphasis on the Iranian and Afghan domains. Restoration of the deformation places these domains within the Pamir/western Tibetan orogen, allowing lateral continuity of tectonic units and structures disrupted by Alpine-Himalayan orogenic processes.

Closure of oceanic basins that opened within the Iranian Cimmerides is closely linked to shortening and westward extrusion in Tibet and the Pamir Mountains. This extrusion is accommodated by Sabzevar-Nain-Baft and Sistan subduction zones during the late Cretaceous. We infer that the opening of the Sistan Ocean was driven by counter-clockwise rotation of Central Iranian units, while the Sabzevar-Nain-Baft oceanic basin developed as a back-arc basin in the upper plate of the Neo-Tethys subduction zone below the Sanandaj-Sirjan Zone. The Waser Suture is proposed as a candidate for the missing link accommodating relative motion between the China blocks and Eurasia until the early Cretaceous.

According to our reconstruction, the amount of extrusion is likely exceeded that of eastern Tibet, reaching more than 1000 km, between ~100 and 45 Ma. Iranian and Afghan tectonic units therefore represent one of the largest extrusion systems within the Tethyan orogen.