Calcite carbonatite
Calcite carbonatites are igneous rocks that belong to the group of carbonatites . They consist of more than 50 percent by volume calcite . Calcite carbonatites can be further divided into coarse-grained sövites and medium- to fine-grained alvikites .
definition
Calcite carbonatites are defined by the modal calcite content, which must be more than 50 percent by volume. The definition was first made in 1978 by Albert Fahrtisen .
mineralogy
The main mineral in calcite carbonatites is by definition calcite, which is represented with more than 50 percent by volume.
Secondary components are the carbonate anchorite , the phosphate apatite , clinopyroxene ( aegirine-augite ), biotite , magnetite and quartz , fluorite and sulphide minerals (such as pyrite , chalcopyrite and galena ), occasionally also amphibole , allanite , chlorite , melilite , monticellite, are added , Olivine , garnet (high in titanium), monazite , phlogopite , pyrochlore , titanite and wollastonite .
Post Magma table appear apatite, barite , dolomite , orthoclase , Parisit , rhodochrosite , Strontianit and Synchisit .
Chemical composition
The following table illustrates the chemical composition of calcite carbonatites:
Weight% | Average savit Amba Dongar |
Phlogopit-Sövit Kaiserstuhl |
Average alvikite | Alvikite Kaiserstuhl |
SiO 2 | 2.97 | 2.08 | 1.50 | 1.09 |
TiO 2 | 0.09 | 0.04 | 0.07 | 0.00 |
Al 2 O 3 | 0.16 | 0.49 | 0.18 | 0.17 |
Fe 2 O 3 | 2.63 | 3.60 | 2.70 | 0.91 |
MnO | 0.50 | 0.30 | 0.57 | 0.46 |
MgO | 0.99 | 1.21 | 0.58 | 0.31 |
CaO | 49.34 | 49.51 | 49.40 | 52.20 |
Na 2 O | 0.04 | 0.40 | 0.13 | 0.00 |
K 2 O | 0.06 | 0.51 | 0.08 | 0.00 |
P 2 O 5 | 1.69 | 1.62 | 0.66 | 1.23 |
CO 2 | 39.76 | 37.06 | 39.85 | 41.10 |
SO 3 | 2.29 | |||
BaO | 0.41 | 0.54 | 0.10 | |
SrO | 0.69 | 1.16 | 0.26 | 0.80 |
Occurrence
- Afghanistan
- Angola :
- Australia :
-
Brazil
- Jacupiranga - Hauterivian - 131 million years BP
- Serra Negra , Minas Gerais
- Topira
- People's Republic of China :
-
Germany :
- Altvogtsburg and Schelingen in the Kaiserstuhl - 18 to 13 million years old BP - Burdigalium to Serravallian
- Laacher See
-
Finland :
- Siilinjärvi - Rhyacium - 2094 million years BP
- Sokli - Frasnium - 365 million years BP
-
India :
- Amba Dongar in Gujarat - Danium - 65.5 million years old BP
- Barra - Calymmium - 1490 million years BP
- Danta - Langera - Mahabar - Tertiary
- Kamthai
- Mahadwa - Bhagdari
- Mundwara , Rajasthan
- Munnar , Kerala
- Panwad - Kawant , Gujarat
- Samalpatti
- Sarnu - Dandali
- Sung Valley , Meghalaya - Turonian to Santonian - 90 ± 10 to 84 ± 13 million years BP
- Vinjamur
- Italy :
-
Canada :
- British Columbia :
-
Ontario :
- Argor
- Lackner Lake
- Manitou Island
- Mortinson Lake
- Nemegosenda Lake
- Prairie Lake
- Québec :
-
Cape Verde
- Brava (Santa Bárbara)
-
Kenya :
- Homa Bay
- Lay the Hills
- Nyanza
- Ruri (Ruri-South)
- Tinderet
- Malawi :
-
Morocco :
- Tamazeght near Midelt , High Atlas
- Mongolia :
-
Namibia :
- Thick Willem - Ypresium - 49 million years BP
- Kalkfeld
- Norway :
- Paraguay :
- Zambia :
-
Sweden :
- Alnön (type locality)
- Smedsgården on Alnön - Ediacarium - 560 million years old BP
-
South Africa :
- Kruidfontein
- Phalaborwa - Orosirian - 2047 million years BP
- Sandhead drif
- Tanzania :
- Turkey :
- Uganda :
- United States of America :
Individual evidence
- ↑ Fahrtisen , A .: IUGS Subcomission on the Systematics of Igneous Rocks. Classification and nomenclature of volcanic rocks, lamprophyres, carbonatites and melilite rocks. Recommendations and suggestions. In: New Yearbook for Mineralogy . Treatises. Vol. 143. Stuttgart 1978, p. 1-14 .
- ↑ R. Ayuso et al: Preliminary radiogenic isotope study on the origin of the Khanneshin carbonatite complex, Helmand Province, Afghanistan . In: Journal of Geochemical Exploration . 2013.
- ↑ M. Santosh et al: Rare Earth Element Geochemistry of the Munnar Carbonatite, Central Kerala . In: Journal Geological Society of India . Vol. 29, 1987, pp. 335-343 .
- ↑ P. Kresten: Alnöområdet . Ed .: Lundqvist, T .: Beskrivning till berggrundskartan över västernorrlandslän. ser Ba 31. Sveriges geologiska undersökening, 1990, p. 238-278 .
- ^ GR McCormick, RC Heathcote: Mineral chemistry and petrogenesis of carbonatite intrusions . In: American Mineralogist . Vol. 72, 1987, pp. 59-66 .
- ^ GR McCormick, RC Heathcote: Major-cation substitution in phlogopite and evolution of carbonatites in the Potash Sulfur Springs complex, Garland County, Arkansas . In: American Mineralogist . Vol. 74, 1989, pp. 132-140 .