Kimberlite Section
Kimberlite is a kind of potassic volcanic rock popular for sometimes containing diamonds. It is namsed after the town of Kimberley located in South Africa, where the discovery of an 83.5 carats (16.7 g) diamond in 1871 spawned a diamond rush, eventually creating the Big Hole.
Kimberlite occurs in the Earth's crust in vertical structures which are called as kimberlite pipes. These are the most important source of mined diamonds. Kimberlites are generally formed deep within the mantle, at between 150 and 450 kilometres depth, from anomalously enriched exotic mantle compositions, and are erupted rapidly and violently, often with considerable carbon dioxide and various other volatile components. It is this depth of melting and generation which makes kimberlites prone to host diamond xenocrysts.
Kimberlite has in several ways attracted more attention than its relative volume might suggest that it deserves. This is mainly because it serves as a carrier of diamonds and garnet peridotite mantle xenoliths to the Earth's surface. In addition, its derivation from depths greater than any other igneous rock type, and the extreme magma composition that it reflects in terms of low silica content and high levels of incompatible trace element enrichment, make an understanding of kimberlite petrogenesis important. The study of kimberlite has the potential to serve valuable information on the composition of the deep mantle, and melting processes occurring at or near the interface between the cratonic continental lithosphere and the underlying convecting asthenospheric mantle.
