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Carbonatite (/ kɑːrˈbɒnəˌtaɪt /) is a type of intrusive or extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. [ 1 ] Carbonatites may be confused with marble and may require geochemical verification. Carbonatites usually occur as small plugs within zoned alkalic intrusive complexes ...
Siilinjärvi is the second largest carbonatite complex in Finland after the Sokli formation, and one of the oldest carbonatites on Earth at 2610±4 Ma. [1] The carbonatite complex consists of a roughly 16 km long steeply dipping lenticular body surrounded by granite gneiss. The maximum width of the body is 1.5 km and the surface area is 14.7 km 2.
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Fenite is a metasomatic alteration associated particularly with carbonatite intrusions and created, very rarely, by advanced carbon dioxide alteration (carbonation) of felsic and mafic rocks. It is characterised by the presence of alkali feldspar, sodic pyroxene and sodic amphibole. Fenite alteration is known, but restricted in distribution ...
Specimen 7.5 cm) Sovite (or sövite) is the coarse-grained variety (or facies) of carbonatite, an intrusive, igneous rock. The fine-grained variety of carbonatite is known as alvikite. [1] The two varieties are distinguished by minor and trace element compositions. [2] Sovite is often a medium-to-coarse-grained calcite rock with variable ...
Natrocarbonatite. Natrocarbonatite is a rare carbonatite lava which erupts from the Ol Doinyo Lengai volcano in Tanzania within the East African Rift of eastern Africa. Natrocarbonatite lavas were first documented in 1962, by J. B. Dawson. [1][2]
The Fen Complex is a roughly circular area about three kilometres in diameter. It is located just west of the Oslo graben. Radiometric age dating on the carbonatites gave an age of 539 +/- 14 Myr. The host rocks for the intrusions are middle Proterozoic granites and gneiss and the complex was associated with the Cambrian rifting of the cratonic ...
Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO 3), and dolomite rock (also known as dolostone), which is composed of mineral dolomite (CaMg (CO 3) 2). They are usually classified based on ...