Alkaline Rocks and Carbonatites of the World

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Buriti And Mata Azul

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Occurrence number: 
025-00-049
Country: 
Brazil
Region: 
Goias
Location: 
Longitude: -51.2, Latitude: -16.37

Buriti is an Ipora Group intrusion of about 16 km2 displaced by a north-south-trending sinistral fault and emplaced in Precambrian granites and syenites and sandstones of the Devonian Furnas Formation. It consists of alaskites of K-feldspar, quartz, hornblende and opaques, together with 'nordmarkites' of perthite, plagioclase and quartz. It is not clear from the available descriptions whether it is peralkaline.
The nearby Mata Azul tinguaite dyke is 2.5 km in length and 7-20 m thick; it has a fluidal texture at the margins. It contains phenocrysts of sanidine of 0.5-2 cm, nepheline, aegirine-augite/aegirine, biotite, sphene and dodecahedra of (?)analcime, set in a matrix of the same mineralogy together with opaques and secondary cancrinite.

References: 
PENA, G.S. and FIGUEIREDO, A.J.A. 1975. Projeto Goiama II, relatorio final. Departamento Nacional da Producao Mineral. Companhia de Pesquisa de Recursos Minerais, 1: 121-61. MARQUES, V.J. and RIPPEL, C. 1970. Tinguaito porfiro da fazenda Mata Azul, municipio de Ipora, GO, Brasil. Anais Congresso Brasileira de Geologia, 24(1): 366-9
Fig. 196 The Ipora Group of occurrences of alkaline intrusions of central Goias.
Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith