1. What is kimberlite? Ultramafic, incompatible-element and volatile rich igneous rock formed by melting and entrainment of deep mantle material Occur in volcanic and sub-volcanic settings Complex, hybrid rocks → wide range of characteristics Heterogeneous – “magma” includes the following components: solids - mantle-derived silicate melt - phenocrysts, groundmass volatiles - H2O / CO2 → segregations, deuteric alteration, eruption Complicated by: contamination with crustal material during emplacement / eruption and; considerable textural variation associated with different intrusion / eruption / reworking processes weathering

2. Commonly, they exhibit a distinctive inequigranular texture resulting from the presence of macrocrysts (and in some instances megacrysts) set in a fine grained matrix. The megacryst/macrocryst assemblage consists of rounded anhedral crystals of magnesian ilmenite, Cr-poor titanian pyrope, olivine, Cr-poor clinopyroxene, phlogopite, enstatite and Ti-poor chromite. Olivine is the dominant member of the macrocryst assemblage.

4. Morphology of Kimberlite Based on studies of numerous kimberlite deposits, geologists have divided kimberlites into 3 distinct units based on their morphology and petrology. These units are: 1) Crater Facies Kimberlite 2) Diatreme Facies Kimberlite 3) Hypabyssal Facies Kimberlite

5. 1)Crater Facies Kimberlite: The surface morphology of an unweathered kimberlite is characterised by a crater, up to 2 kilometers in diameter, whose floor may be several hundred meters below ground level.

6. he crater is generally deepest in the middle. Around the crater is a tuff ring which is relatively small, generally less than 30 meters, when compared to the diameter of the crater. Two main categories of rocks are found in crater facies kimberlite: a.)pyroclastic, those deposited by eruptive forces; b.)epiclastic, which are rocks reworked by water.

7. 2) Diatreme Facies Kimberlite Kimberlite diatremes are 1-2 kilometer deep, generally carrot-shaped bodies which are circular to elliptical at surface and taper with depth. The dip contact with the host rocks is usually 80-85 degrees. The zone is characterized by fragmented volcaniclastic kimberlitic material and xenoliths plucked from various levels in the Earths crust during the kimberlites journey to surface.

8. Pelletal lapilli - appear to have formed by the rapid crystallization of a volatile poor magma containing phenocrysts. They are characterised by a crystal nucleus surrounded by microphenocrysts which align themselves tangentially to the central crystal.Pelletal lapilli

9. Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation. Kernel grain usually country rock. Magmatic nucleation about a nucleating center. Matrix composed almost entirely of fine- grained diopside, serpentine and phlogopite.

10. 3) Hypabyssal Facies Kimberlite These rocks are formed by the crystallization of hot, volatile-rich kimberlite magma. Generally, they lack fragmentation features and appear igneous.

11. i. Calcite-serpentine segregations in matrix. ii. Globular segregations of kimberlite in a carbonate-rich matrix. iii. Rock fragments have been metamorphosed or exhibit concentric zoning. iv. Inequigranular texture creates a pseudoporphyritic texture.

18. Facts: about Kimberlite It is named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat (16.7 g) diamond in 1871 spawned a diamond rush, eventually creating the Big Hole.Kimberley South AfricaBig Hole Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes.crustkimberlite pipes