What is kimberlite? Ultramafic, incompatible-element and volatile rich igneous rock formed by...
19
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
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Transcript of What is kimberlite? Ultramafic, incompatible-element and volatile rich igneous rock formed by...
What is kimberlite1048714 Ultramafic incompatible-element and volatile rich igneous
rock formed by melting and entrainment of deep mantlematerial
1048714 Occur in volcanic and sub-volcanic settings1048714 Complex hybrid rocks rarr wide range of characteristics
1048714 Heterogeneous ndash ldquomagmardquo includes the followingcomponents
1048714 solids - mantle-derived1048714 silicate melt - phenocrysts groundmass
1048714 volatiles - H2O CO2 rarr segregations deuteric alterationeruption
1048714 Complicated by1048714 contamination with crustal material during emplacement
eruption and1048714 considerable textural variation associated with different
intrusion eruption reworking processes1048714 weathering
bull Commonly they exhibit a distinctive inequigranular texture resulting from the presence of macrocrysts (and in some instances megacrysts) set in a fine grained matrix
bull The megacrystmacrocryst 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
Morphology of Kimberlite
bull 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 Kimberlite2) Diatreme Facies Kimberlite3) Hypabyssal Facies Kimberlite
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
bull 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
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
bull Commonly they exhibit a distinctive inequigranular texture resulting from the presence of macrocrysts (and in some instances megacrysts) set in a fine grained matrix
bull The megacrystmacrocryst 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
Morphology of Kimberlite
bull 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 Kimberlite2) Diatreme Facies Kimberlite3) Hypabyssal Facies Kimberlite
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
bull 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
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
Morphology of Kimberlite
bull 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 Kimberlite2) Diatreme Facies Kimberlite3) Hypabyssal Facies Kimberlite
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
bull 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
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
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
bull 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
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
bull 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
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
2) Diatreme Facies Kimberlite
bull 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
bull 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
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
bull 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
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
bull Nucleated autoliths - similar to pelletal lapilli but lacking microphenocryst orientation Kernel grain usually country rock Magmatic nucleation about a nucleating center
bull Matrix composed almost entirely of fine-grained diopside serpentine and phlogopite
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
3) Hypabyssal Facies Kimberlite
bull These rocks are formed by the crystallization of hot volatile-rich kimberlite magma Generally they lack fragmentation features and appear igneous
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
i Calcite-serpentine segregations in matrix ii Globular segregations of kimberlite in a carbonate-rich matrixiii Rock fragments have been metamorphosed or exhibit concentric zoningiv Inequigranular texture creates a pseudoporphyritic texture
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
Facts about Kimberlite
bull It is named after the town of Kimberley in South Africa where the discovery of an 835-carat (167 g) diamond in 1871 spawned a diamond rush eventually creating the Big Hole
bull Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
- Slide 1
- Slide 2
- Slide 3
- Morphology of Kimberlite
- Crater Facies Kimberlite
- Slide 6
- 2) Diatreme Facies Kimberlite
- Slide 8
- Slide 9
- 3) Hypabyssal Facies Kimberlite
- Slide 11
- Slide 12
- Slide 13
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Facts about Kimberlite
- Slide 19
-
