The Qom Salt Dome and it?s Relation to Evolution of theQom Sedimentary Basin
The Qom salt dome is located at 25km NW of Qom city and in the N of the main Saveh- Qom road. Its structural position is in the western of Alborz anticlinal system of the Qom Alborz range and approximately which is of Mio-Pliocene age. It has a regular gentle morphological shape. It covers an area about 6.5km2with a height of 285m above the adjacent plain and 456km3 volumes at the surface. The gravimetric studies show the conic shape of the salt domes in subsurface region, which are continued in Neogene layers. It is the most and well-pronounced spectacular diapir among the many present in the region. Its stratigraphic position show that it is younger than Pliocene. The conglomerate that has been broken and brought up diapir has some tuff and andesite rocks carried out with flow of halite. It is limited in N by volcanic intrusions of Manzarieh and in the S by Dochah anticline. Both in the N and S some transverse faults, which separate the plain, like surface and the Alborz Neogene anticlinal system in which the layers have very gentle slope. The E.C study in the region done by the water allthority of Qom shows some diapirs anomaly through out of the diapir which will be of some distance off-set from distribution symmetry and is the principal diapir source contaminating the borehole drilled in the region. The halite source may be in the layers from Eocene, Oligocene (Lower Red formation), Miocene (Qom formation) and Upper Miocene (Upper Red formation). The intrusive volcanic will also provide the decomposition of some evaporative materials. As field observation shows the old diapir will be younger than Pliocene and even Late Pleistocene period. It is a source of salinity of surface soil and water, drained to Hoze-e-Soltan salt lake and also the source of salinity of ground water, in the S and W (through Saveh road). The salinity will be reached somewhere at 68 mz/s, which is about 5 times more than normal salinity in region could be observed.