Alkaline Rocks and Carbonatites of the World

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Serra Negra

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Occurrence number: 
025-00-061
Country: 
Brazil
Region: 
Minas Gerais
Location: 
Longitude: -46.83, Latitude: -18.92

A large oval complex of about 65 km2 is emplaced into quartzites and phyllites of the Precambrian Bambui Group, which it domes. A thick lateritic cover averages about 150 m in thickness. Drilling has shown the core to consist of carbonatite, pyroxenite, dunite and peridotite. Shonkinites and jacupirangites apparently surround these inner rocks. Pyrochlore, perovskite and baddeleyite occur in the carbonatite and pyroxenite. A little fenitization of the country rocks has been observed.

Economic: 
Pyrochlore occurs in carbonatite and there is disseminated Th-U mineralization. At least 200 million tons of anatase-rich ore averaging 27% TiO2 occur in the lateritic cover (Rodrigues and Lima, 1984).
Age: 
K-Ar on biotite from peridotite gave 81.7 and 81.5 Ma (Hasui and Cordani, 1968).
References: 
FILHO, J.G.C.S. 1974. Prospeccao de uranio nas chamines alcalinas de Serra Negra e Salitre - MG. Boletim Comissao Nacional de Energia Nuclear, 9: 1-41. HASUI, Y. and CORDANI, U.G. 1968. Idades potassio-argonio de rochas eruptivas Mesozoica do oeste mineiro e sul de Goias. Anais Congresso Brasileiro de Geologia, 22: 139-43. RODRIGUES, C. de S. and LIMA, P.R.A. dos S. 1984. Carbonatitic complexes in Brazil. Companhia Brasileira de Metalurgia e Mineracao: 1-17
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith