Alkaline Rocks and Carbonatites of the World

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Santa Fe (Tiva Pressa)

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Occurrence number: 
025-00-043
Country: 
Brazil
Region: 
Goias
Location: 
Longitude: -51.17, Latitude: -15.75

Santa Fe is a zoned ultramafic intrusion of the Ipora Group of about 45 km2, emplaced in Precambrian granites and gneisses and Devonian sandstones and conglomerates. A large core consists of serpentinized dunite, together with peridotite, wehrlite and olivine clinopyroxenite. The dunites contain a little pyroxene and 5-10% opaques. Malignite and missourite are subordinate rock types, the latter comprising diopside/augite (50-60%), leucite (15-20%), olivine (10-15%) and biotite (5-10%), and some apatite and opaques, while the malignites consist of poikilitic orthoclase, nepheline, diopside/augite, biotite, apatite and opaques. A metamorphic aureole extends up to 500 m from the contact. Dykes of peralkaline quartz syenite occur containing 30-50% aegirine. Zones of vermiculitization occur within the dunites and peridotite.

Economic: 
Garnierite occurs in residual laterite; vermiculite is also present.
Age: 
K-Ar determinations yielded 74.4±3.4 Ma on essexite; 84.7±1.8 Ma on missourite; 82.6±4.5 to 88.4±2.7 Ma on malignite and 86.6± 4.5 Ma on a lamprophyre dyke (Barbour et al. 1979).
References: 
BARBOUR, A.P. 1976. Geologia do macico ultramafico de Santa Fe, Goias. Livre Docencia, Thesis (unpublished). Institute of Geosciences, University of Sao Paulo. BARBOUR, A.P., KAWASHITA, K., GIRARDI, V.A.V. and SOUZA, A.M.S. de, 1979. Geocronologia do complexo mafico-ultramafico alcalino de Santa Fe, Goias. Boletim Instituto de Geociencias, USP, 10: 11-8. 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
Fig.196 The Ipora Group of occurrences of alkaline intrusions of central Goias. Fig. 197 Santa Fe (after Barbour, 1976, Fig. 2).
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