Geology of Iran

Due to the presence of great quantities of limestone, many caves have been formed in Iran. The most famous of these caves are to be found in Azarbaijan, in Kurdestan, near Hamadan, Isfahan Province and in the Teheran area. Unfortunately several of these regions are in rather dangerous area.

Most of the outcrops of carbonate rocks are of Cretaceous and Tertiary Age. The sediments were deposited at the bottom of a shallow and oxygene rich sea. Then they were covered by other sediments, finally the pressure of the overlying rocks and the chemical reactions in the groundwater created limestone from the calcareous mud. This took millions of years. Much later the rock was uplifted by tectonic forces, most likely the orogeny of the Hadschar and Ural during Miocene and Pliocene. The result was the Iranian Plateau or Persian Plateau, which formed during the last 20 Million years as a result of the collision of Arabian Plate and Eurasian Plate. Karstification started, when the limestones and dolomites reached a height above sea level which created drainage systems. Most caves are of Pliocene age.

Quite common are salt diapirs, mostly of the Paleozoic Hormoz formation, all over Iran, some of them of enormous size. The salt is pressed upwards along faults which are a result of the orogeny. Quite exceptional are salt glaciers wher the salt is flowing down the flanks of the dome. Some of the saltdomes are more than 1000 m higher than the surrounding area, for example Kangan salt dome. In humid climates the salt would be washed away by rainwater, but here in the arid and semi-arid climate it is possible for salt to exist on the surface. Sporadic rainfall creates solutional caves in the salt without washing the salt away. As a result some of the biggest and most interesting salt caves of the world can be found in Iran, most of them on the island Hormuz.