Oligo-Miocene lithofacies units in north of Sanandaj-Sirjan Zone: A case study in east and northeast of Hamedan

In this study, more than 200 m thick Oligo-Miocene sediment in east and northeast of Hamedan (Sanandaj-Sirjan zone), were studied in order to define rock units and compare with Qom Formation in Central Iran. Oligocene sediments (the Lower Red Formation) consists of marl, sandy marl and congolomerate units (Oc and Om). Five rock units, two of which are introduced for the frist time, were recognized in Miocene sediments: lower units (OMc1 and OMl: conglomerate and limestone), middle units (OMm and OMC2: marlstonen and cobglomerate) and the upper unit (OMr: reef limestone). Compared with Central Iran, clastic units are more abundant and no evaporitic condition existed in the study area. The Upper Red Formation has no outcrop in this region and Oligo-Miocene sediments are directly overlaid by Plio-Quaternary sediments. Evidences show a, d, e and f units of Qom Formation are missing in this region and other stratigraphic equivalent units of Qom formation in the study area are Miocene (Aquitanian) in age.