Diatreme
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A Diatreme is a volcanic pipe or feature formed by a gas or volatile rich explosive magma. Diatremes often breach the surface and produce a tuff cone or a filled relatively shallow crater known as a maar or other volcanic pipes. The term has been applied more generally to any concave body of broken rock or breccia, generally formed by explosive or hydrostatic forces, whether or not it is related to volcanism. Some diatreme explosions may result from the interaction of hot magma and relatively shallow groundwater.
Kimberlite and lamproite volcanic pipes associated with diamond occurrences are usually considered to be volatile charged piercement structures or diatreme volcanic features from the lower crust or upper mantle. Many copper and base metal ore deposits have associated intrusive breccia pipes which are rich in ore minerals have been referred to as diatreme in nature.
An intrusion is the material causing the diatremic piercement. Many volcanic processes produce piercement structures through intrusions of igneous rock. However, most igneous intrusions are not considered diatremic.
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