Supporting Information for [Configuration and timing of collision between Arabia and Eurasia in the Zagros collision zone, Fars, southern Iran]

Onset timing in the Zagros collisional belt is critically important for understanding the early history of Zagros-Iran Plateau and providing constraints on orogenic expansion. Despite this importance, the geometry and timing of initial Arabia-Eurasia continental collision is not well known. Here, we analyze sandstone petrography, in-suite detrital zircon U-Pb-Hf and trace elements and Cr-spinel electronic microprobe data from Upper Cretaceous-Miocene strata of the Zagros foreland basin, inner Fars, southern Iran. Our data show that the foreland strata experienced two provenance changes since late Cretaceous. The first appearance of ophiolite-affinity detritus occurs in the latest Maastrichtian to early Paleocene Sachun Formation that was deposited atop the Arabian continental margin. The lack of Eurasian-affinity zircon in the Sachun Formation indicates that obduction predated Arabia-Eurasia continental collision. During late Oligocene-early Miocene (25-21.5 Ma) time, Eurasian-affinity detrital zircon were first deposited in the Razak Formation, marking that collision between Arabia and Eurasia initiated during this time