Salt glacier

Flow of solid salt on Earth's surface

A salt glacier (or namakier) is a rare flow of salt that is created when a rising diapir in a salt dome breaches the surface of Earth. The name ‘salt glacier’ was given to this phenomenon due to the similarity of movement when compared with ice glaciers. The causes of these formations is primarily due to salt's unique properties and its surrounding geologic environment. A rising body of salt is referred to as a diapir; which rises to the surface and feeds the salt glacier. Salt structures are usually composed of halite, anhydrite, gypsum and clay minerals. Clays may be brought up with the salt, turning it dark. These salt flows are rare on Earth. In a more recent discovery, scientists have found that they also occur on Mars,

The salt glaciers of the Zagros Mountains in Iran are halite whereas the salt glacier of Lüneburg Kalkberg, Germany is composed of gypsum and carbonate minerals. Ancient flows have been preserved in various rock records by sedimentation. Late Triassic salt glaciers repeatedly flowed onto a basin in Germany and were buried with sediment to create a series of preserved glaciers. Miocene glaciers flowed into sheets in the northern Gulf of Mexico and were similarly preserved by overriding sediment.

The sources of salt glaciers are salt deposits. Over time sediments, rock and debris cover the deposit, causing layers to build up over the salt. Due to its crystalline structure, salt remains at the same density while the sediment above begins to compress and become denser. The density contrast is the mechanism in which salt begins to rise. Diapirs rise and pierce the surface, allowing the salt to flow because of gravity. Piercing the overburden is crucial for salt glaciers to form, and can occur in three ways. Active diapirism develops as the rising salt itself pushes and forces the overburden upward and sideways. Passive diapirism occurs when the salt always remains near the surface and the sediment builds up around it rather than over it. Reactive diapirism is the result of regional extension caused by rifting. The overburden becomes weak and thin, which allows the salt body to travel upwards. Salt glaciers are a frequent topic in salt tectonics, which is the study of salt causing deformation The traps are also being studied to serve as potential storage vessels for waste and fuels.