Revision of the stratigraphic position of red deposits attributed to the Neogene in the north of Eshtehard, southwest of Alborz Province

Based on tectonic and sedimentological characteristics, Neogene deposits were chosen to review due to their high extent in the Eshtehard area (Alborz Province) and lack of previous information. These sediments were not determined in the area due to an indistinct lower boundary and the absence of the Qom Formation, and they were attributed to the Neogene. The clastic-evaporitic continental deposits in the north of Eshtehard, Mard Abad, Salt Mine and Rud Shur sections were divided into five sedimentary units (M1 to M5) based on facies and lithological characteristics. Lithological studies showed that the composition of the sediments of the M1 to M4 units is very different from that of the M5 unit. Field observations reveal an erosional unconformity between M4 and M5 units, and the salt dome has pierced M4 but has no effect on unit M5. Comparing the Neogene units of the Eshtehard area with equivalent sedimentary deposits in the Avaj area, it seems that the deposits of the M1 to M4 units in the Eshtehard area are equivalent to the Upper Red Formation, and the M5 unit belongs to the Pliocene and suggests that it should be considered as a new formation.