Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences



Occurrence number: 
Sao Paulo
Longitude: -49.2, Latitude: -24.5

This is a body of about 4.5 km2 elongated northwest-southeast and intruded into Precambrian granites of the Tres Corregos complex. Itapirapua comprises mainly nepheline syenites with lesser amounts of melteigite, malignite, pulaskite, mariupolite and carbonatite; dykes of tinguaite are present within and around the intrusion and some marginal fenitization occurs. The nepheline syenites contain aegirine-augite/aegirine, studied by Gomes et al. (1970), and much cancrinite, some sodalite and melanite, zoned examples of which were investigated by Gomes (1969); biotite, wollastonite, pectolite, fluorite, eucolite, pyrite, pyrrhotine, calcite and zeolites also occur. Analyses of a range of rocks are given by Gomes and Dutra (1970). The carbonatites, which form small dykes and veins, are orthoclase sovites and apatite-orthoclase sovites. They are confined to the central part of the intrusion where they cut nepheline syenite; analyses are available in Gomes and Dutra (1969). The fenites include aegirine-augite and alkali-amphibole-bearing varieties.

A funnel-shaped orebody on the southern side of the complex is being worked for granular magnetite.
104.8 Ma on alkali feldspar from nepheline syenite and 101.4 Ma on biotite from melteigite, both by K-Ar (Amaral et al. 1967; Gomes and Cordani, 1965).

AMARAL, G., BUSHEE, J., CORDANI, U.G., KAWASHITA, K. and REYNOLDS, J.H. 1967. Potassium-argon ages of alkaline rocks from southern Brazil. Geochimica et Cosmochimica Acta, 31: 117-42.
FERREIRA, F.J.F. and ALGARTE, J.P. 1979. O comportamento aeromagnetometrico-cintilometrico das principais rochas alcalinas dos estados de Sao Paulo e Parana. Atas do 29 Simposio Regional de Geologia, Rio Claro, 2: 195-208.
GOMES, C.B. 1969. Electron microprobe analysis of zoned melanites. American Mineralogist, 54: 1654-61.
GOMES, C.B. 1970. Petrologia do macico alcalino de Itapirapua. Boletim IGA, Instituto de Geociencias e Astronomica, Universidade de Sao Paulo, 1: 77-197.
GOMES, C.B. and CORDANI, U.G. 1965. Geocronologia do macico alcalino de Itapirapua, SP. Anais da Academia Brasileira de Ciencias, 37: 497-501.
GOMES, C.B. and DUTRA, C.V. 1969. A short note about the carbonatites from Itapirapua, Sao Paulo, Brazil. Anais da Academia Brasileira de Ciencias, 41: 195-8.
GOMES, C.B. and DUTRA, C.V. 1970. Some geological features of the alkaline rocks of Itapirapua, Sao Paulo, Brazil. Anais da Academia Brasileira de Ciencias, 42: 521-34.
GOMES, C.B., MORO, S.L. and DUTRA, C.V. 1970. Pyroxenes from the alkaline rocks of Itapirapua, Sao Paulo, Brazil. American Mineralogist, 55: 224-30

Fig. 1_219 The Itapirapua and Barra do Itapirapua intrusions (after D'Elboux et al. 1982, Fig. 3).
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith