Gholamreza Fotoohi Rad

Diatreme (volcanic vent): When hot material escapes from the Earth's interior in an eruption, the vent of the volcano and the feeder pipe below fill with breccia as the eruption wanes. The resulting structure is called a diatreme or volcanic vent. Much research has clarified the mechanism of diatreme formation. Studies of the minerals and rocks contained in some diatremes have shown that they only form at great depths - about 100 km or more - within the upper mantle. There is a diatreme in the legendary Kimberley Mines in South Africa, one of the largest diamond mines in the world. This diatreme is composed of peridotite, an ultramafic rock composed mostly of olivine and pyroxene. It also contains diamonds, which are formed from carbon under high pressure in the mantle with mixed fragments of mantle rock picked up by the magma as it rose to the Earth's surface. This diatreme is seen as if a well had been drilled into the mantle to a depth of 300 km. The fragments that the magma picked up as it rose provide the only direct evidence of the upper mantle material, which is composed mainly of peridotite.