stripes
Occurrence number:
025-00-097
Country:
Brazil
Region:
Sao Paulo
Location:
Longitude: -47.4, Latitude: -23.7
Carbonatite:
No
This is a small dyke of porphyritic shonkinite with phenocrysts of biotite, aegirine-augite, apatite and orthoclase, in a groundmass of the same minerals plus nepheline. Weathered syenitic rocks also outcrop.
Age:
121.8 Ma by K-Ar on biotite (Amaral et al. 1967).
References:
KNECHT, T. 1960. Notas preliminares sobre novas ocorrencias de rochas alcalinas no estado de S. Paulo. Boletim da Sociedade Brasileira de Geologia, 9(1): 71-6.
Melcher, quoted in AMARAL, G., BUSHEE, J., CORDANI, U.G., KAWASHITA, K. and REYNOLDS, J.H. 1967. Geochimica et Cosmochimica Acta, 31: 117-42
Location: