Alkaline Rocks and Carbonatites of the World

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Occurrence number: 
Longitude: -49.38, Latitude: -24.65

Banhadao is a multiple intrusion of some 11 km2 intruding the Tres Corregos granitic complex. Nepheline syenites are predominant and variable, aegirine-augite/aegirine and melanite being the principal mafic minerals with some sodic amphibole; nepheline may be altered to cancrinite and pectolite. Phlogopite melteigites and minor feldspar-melanite ijolites and malignites also occur. Phonolite dykes are present within and around the complex.

Geochemical work on soils has proved high concentrations of Nb, Ti, Zr and Al.
Biotite from malignite gave 118±4 Ma by K-Ar and anorthoclase from foyaite 68±1 Ma (Hama et al. 1977).
HAMA, M., ALGARTE, J.P., PAIVA, I.P. and RODRIGUES, J.C. 1977. Idades K/Ar do macico alcalino do Banhadao e do complexo Bairro da Cruz. In Atas do I Simposio de Geologia Regional, Sociedade Brasileira de Geologia Nucleo de Sao Paulo, Sao Paulo: 170-8. KAEFER, L.Q. and ALGARTE, J.P. 1972. Macico alcalino de Banhadao. Estudos preliminares. Anais Congresso Brasileiro de Geologia, 26(1): 57-64. RUBERTI, E. and GOMES, C.B. 1984. O macico alcalino do Banhadao: geologia e petragrafia. Anais Congresso Brasileiro de Geologia, 33: 4400-12
Fig. 218 Banhadao (after Ruberti and Gomes, 1984, Fig. 1).
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