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Gutiã©Rrez, Francisco; Lizaga, Ivã¡N
Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: the unique case of the ambal ridge in the karun river, zagros mountains, iran
Geomorphology
2015
254
88
103

Ambal ridge, covering 4 km2, is a salt pillowof Gachsaran Formationwith significant salt exposures in direct contact  with the Karun River, Zagros Mountains. The highly cavernous salt dome is currently being flooded by the  Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun  River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional  unloading. Around 30% of the salt dome is affected by large landslides up to ca. 50 × 106 m3 in volume. Slope  oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. A total of  693 sinkholes have been inventoried (170 sinkholes/km2), for which a scaling relationship has been produced.  The depressions occur preferentially along a belt with a high degree of clustering. This spatial distribution is  controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound  depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by  water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures  220–280 m across, expressed by systems of arcuate fissures and scarps. Rapid subsurface salt dissolution is  expected to generate and reactivate a large number of sinkholes and may reactivate landslideswith a significant  vertical component due to lack of basal support.

Salt karst; Halokinesis; Human-induced subsidence; Salination
0169-555X
10.1016/j.geomorph.2015.11.020
Gutiã©Rrez, Francisco; Lizaga, Ivã¡N, 2015, Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: the unique case of the ambal ridge in the karun river, zagros mountains, iran , Geomorphology , 254 , 88 - 103 http://dx.doi.org/10.1016/j.geomorph.2015.11.020, PDF