Pseudo Volcanic Features
Those topographic features that resemble the volcanic landforms but are non-volcanic in origin are known as pseudo volcanic features. The pseudo volcanic features include meteorite crater, mud volcanoes, and salt plugs.
Pseudo Volcanic features
- A crater is a depression usually circular formed by either the extrusion of volcanic material or by the impact of any meteorite.
- A rootless cone is a pseudo creator which resembles a real volcanic crater, but it is not of volcanic origin. It does not have an actual volcanic vent from which the lava has erupted. The rootless cone is characterized by the absence of the magma conduit which connects the crater to the Magma chamber below the Earth's surface.
- The meteorite craters are formed by the impact of falling meteorites from the space on earth. They resemble like a crater lake; for example, the Lonar lake in Buldhana is an example of meteorite crater lake which has been formed as a result of the impact of a giant meteorite. Other examples of meteorite craters include Siberian crater, Shiva crater on the Mumbai Offshore basin etc.
- Apart from these, the craters developed due to the anthropogenic activities are also referred as pseudo volcanic features. It includes the craters formed by the explosion of bombs, mine blasts, etc. which resemble the features of a crater.
Salt plugs or salt dome
- The salt plug is a dome-like structure formed by the stratified rocks which contain the central core of salt, which has been formed by the upward movement of the salt deposits. Under high pressure, the salt deposits deform plastically and deform and pierce the overlying sediments like an intrusive landform.
- Salt extrusions can take the form of salt hills having many features of plug domes or lava cones having peaks and sinkholes, which are visually similar to the volcanic craters formed due to subsidence.
- A mud volcano is a landform formed by the eruption of mud, water, and gases etc. Mud volcanoes can be formed due to several geological processes. The mud volcanoes are not the true volcanoes as they do not produce Lava and are not necessarily driven by the activities of magma. Thus they can be classified under the pseudo volcanic features.
- The Mud volcanoes have usually been found in the subduction zones around the world. They mostly release methane gas along with smaller quantities of Nitrogen and carbon dioxide etc.
- Some mud volcanoes are non-volcanic in origin. The volatile hydrocarbons which have been given off from the petroleum-bearing beds can cause mud eruptions, which can be called as mud volcanoes. These kinds of mud volcanoes have been found at Baku along with the Caspian sea, in Burma, and in southern Balochistan etc.