Evidence for distributed active strike-slip faulting in NW Iran: The Maragheh and Salmas fault zones

The study area is located in the northwestern Iranian plateau and exhibits ongoing convergence between the Arabian and Eurasian plates not absorbed by the Zagros orogenic belt. In this paper, we provide our geological observations made along the Maragheh and Salmas strike-slip fault zones that affect the southern portion of northwest Iran to the south of the North Tabriz Fault. We use a combined methodology to characterize active faulting along these fault zones that included remote-sensing analysis of high-resolution satellite imagery and aerial photographs, digital elevation models (DEMs), tectonic geomorphology investigations and geological field surveys. Active transtension is a common feature along the Maragheh and Salmas faults, and our observations suggested that the onset of active transtension and related local extension along the faults in Pleistocene occurred no earlier than ~2 Ma. The Maragheh and Salmas fault zones contribute to the accommodation of dextral strike-slip faulting in the region between the Main Recent Fault to the south and the North Tabriz Fault to the north. The spatial pattern of strike-slip faulting over the northwest Iranian region (including the North Tabriz fault, the Ahar fault, Salmas and Maragheh fault zones) favors a distributed deformation model, which could help to advance our understanding of geodynamic processes and the level of seismic hazard in this part of the Iranian plateau.