Stratigraphical evidences of the Qom – Zefreh Fault system activity, Central Iran

In the Urumieh-Dokhtar volcanic zone, there are nearly parallel faults to the Zagros zone.They were formed during collision of the Arabic plate with Central Iran plate. The northwest-southeast trending of Qom-Zefreh Fault system has long been recognized as major faults in Central Iran. The general aim of this research is to identify the activity period of this fault and the extent of its effects on stratigraphy. For this purpose, we used the stratigraphical evidences on the geological maps and the stratigraphic columns which can help to determine the history of this fault system where caused regression and transgression during the geological time. The results indicate that oblique motion of Arabia with respect to Eurasia is partitioned in the Qom-Zefreh Fault system. Therefore, the southeast segments (the Kashan and the Zefreh faults) activity has been started from the Upper Cretaceous. However the northwest segments (the Qom and the Ravand faults) activity may be considered from the Pliocene. Activity of the Qom Zefreh Fault system as one of the major inter-continental fault systems is younger than in northwest parts.