Saline dome

A saline dome is a natural structure formed by the increase of Halite (" Sel"), very ductile and lighter than the neighbouring rocks (d=2,16 against d=2,7 on average in the higher crust). Salt while going up can form various structures of kilometric size (Diapir S, domes, layers, pillars etc).

Geology

The deposit of large quantity of salt is related to an arid climate and/or confined surroundings (endoreic Bassin, like the Large Basin of the Nevada or the Plateau Tibetan). In Europe, the great majority of salt exploited date of the Sorted.

The great ductility of salt allows the " cicatrisation" fractures; it is in impermeable fact. Its migration to the top deforms the neighbouring layers in Antiforme. The association of a structure antiforme and an impermeable layer allows the trapping of the Hydrocarbures. These structures form the majority of the sources of oil in the Gulf of Mexico. Because of their impermeable nature, these domes are also used to store dangerous raw materials or matters.

One can observe rock salt with the outcrop only in the arid mediums (like the mountains of Iran, to see illustration). Indeed, the Halite is very easily dissolved in water.

The salt deposits also make it possible to locate the deformation: the great ductility of these rocks form a " lay down savon" in which enraciner the Faille S. Ainsi can, the chain of the the Jura is very directly related to the presence of évaporite of Sorted in-depth.

Islands formed by saline domes

In Louisiana, the island Avery.
With the Quebec, the Iles-de-la-Madeleine.

Note

The term “dome saline” is sometimes used, faultily, to indicate silos in the shape of dome and which contain salt to de-ice the roads.

References

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