A diatreme is a breccia-filled volcanic pipe that was formed by a gaseous explosion. Diatremes often breach the surface and produce a tuff cone, 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 tuff-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 and 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.

Diatremes are sometimes associated with deposition of economic mineral deposits. A significant diatreme event was that which formed the giant Sullivan galena (lead-zinc-silver) orebody in British Columbia, Canada. Other diatremes in British Columbia include the Blackfoot diatreme and Cross diatreme.

[edit] References

• Kimberlite Emplacement Models