Namakdan cave is among the most important geosites in the Qeshm Island Geopark (Hormozgan province, Iran). The salt dome (diapir) of Namakdan is a unique structure in the Island including several outstanding structural, mineralogical, erosional and sedimentary sceneries. In this Geosite the world record Namakdan Cave exists, the world longest salt cave, 6500 meters.
The Namakdan Salt Complex (Combrian) actually includes several smaller geosites. There are Salt flats, Playa, Salt springs, Amazing salt outcrops, Sink holes and many other structure and forms. This geosite has been registered in the National List of Natural Heritages (2010).
The main entrances of cave are N1, N2 and N3. N1 is open for general visits; visit to N2 needs arrangements with geopark management and should be done by geopark guide assistance. N3 is very delicate and also dangerous; it is possible to visit just for speleology professionals, geology specialist’s holded particular, written permission from the Qeshm Island Geopark management.
There is a spectacular polygonal form on the southern wall of salt dome in front of the sea. This structure created by salt surface fractures and step erosion in the beddings surface at the same time.
Geology of Salt Dome and Salt Cave
Namakdan Salt dome has an outcrop of 7 kilometer in diameter. This feature has covered the western plunge of Salakh Anticline. Namakdan Salt Dome has been formed from Hormoz Series deposits (preCambrian-Cambrian).
Because of its plasticity nature, it was always inclined to rise up to escape the pressure by upper rocks. Field evidences and seismic logs shows that Hormoz Series had a very slow movement and uplifting; so caused to thinness of the sedimentary formations and making slop in the basement.
Namakdan Salt Cave is located inside Namakdan Salt Dome resulting Karst process and salt dissolution and forming underground channels and galleries. Inside the cave there are different types of sedimentary forms and speleothems. Erosion forms are more than sedimentary forms because of the water high capacity of saturation.
Keywords: diapir , Geopark , Hormoz Series , Hormozgan province , Iran Geology , Iran Geotourism , Namakdan Cave , Namakdan dome , Qeshm Island , world longest salt cave , zamingasht