Alkaline Rocks and Carbonatites of the World

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Itarantim

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Occurrence number: 
025-00-040
Country: 
Brazil
Region: 
Bahia
Location: 
Longitude: -40.12, Latitude: -15.78

Itarantim comprises a major intrusion some 16 km in diameter together with two smaller intrusions to the southeast, all emplaced in a varied suite of Precambrian gneisses and granites which are extensively fenitized adjacent to the complex. The principal rock types are biotite and aegirine-nepheline syenites, with aegirine syenite also occurring. A 100x500 m intrusion of sodalite syenite lies in the southeastern part of the complex and the two smaller intrusions consist of quartz-pyroxene syenite.

Economic: 
Sodalite syenite is quarried as a decorative stone.
Age: 
K-Ar on biotite from syenite gave 469±14 and 520±28 Ma and on microcline from syenite 533±21 Ma (Cordani et al. 1974).
References: 
BARBOSA de DEUS, P., RANGEL, P.dde A. and SILVEIRA, W.P. 1976. Geologia do macico alcalino de Itarantim. Anais Congresso Brasileira de Geologia, 29: 355-6. CORDANI, U., HALPERN, M. and BERENHOLE, M. 1974. Comentarois sobre as determinacoes geocronologicas do Folha Porto Alegre SH.22. In. Carta Geologica do Brasil ao miliuonesimo: texto explicativo. 70-88. Ministerio das Minas e Energia, Departamento Nacional da Producao Mineral, Brasilia
Fig. 195 The Bahia province of alkaline rocks (based principally on the Carta Geologica do Brasil ao milionesimo: Folha Salvador SD. 24 accompanying Pedreira et al. 1976).
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