Alkaline Rocks and Carbonatites of the World

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Morro Redondo


Occurrence number: 
Rio de Janeiro
Longitude: -44.33, Latitude: -22.48

This is an approximately circular intrusion of about 5 km2 cutting Precambrian gneisses, but overlapped on the northern side by Tertiary sedimentary rocks. Biotite foyaite is the most abundant rock type of the intrusion, but sodalite syenites of albite, anorthoclase, aegirine and sodalite also occur. Leucite trachyte with phenocrysts of anorthoclase, amphibole, pyroxene and small leucites has been described.

65 Ma (Ribeiro and Cordani, 1966 quoted in Asmus, 1978).
ASMUS, H.E. 1978. Hipoteses sobre a origem dos sistemas de zonas de fratura oceanicas alinhamentos continentais que ocorrem nas regioes sudeste e sul do Brasil. In. Petrobras. Aspectos estruturais da margem continental leste e sudeste do Brasil. CENPES/DINTEP, Rio de Janeiro (Serie Projeto Remac, no. 4): 39-73. BARBOSA, O. 1933. Eruptivas de Lages, Santa Catarina. Boletim Servico Geologico e Mineralogico, Rio de Janeiro, 69: 15-8. Lamego, 1936.
Fig. 1_204 Distribution of alkaline rocks around Rio de Janeiro.
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