stripes
Occurrence number:
025-00-093
Country:
Brazil
Region:
Sao Paulo
Location:
Longitude: -45.13, Latitude: -23.8
Carbonatite:
No
This is an island of 7.5 km2, 90% of which is occupied by syenite and quartz syenite, the northwestern part being of Precambrian gneisses and hypersthene charnockites. The syenite is a coarse, grey rock of mesoperthite, K-feldspar, aegirine-augite, hornblende, biotite and opaque minerals and grades in places into quartz syenites. Near contacts with Precambrian gneisses and charnockites, the quartz syenites pass into a fine to medium grained, green variety of the same mineralogy but with the addition of remnant orthopyroxene; these rocks are rich in xenoliths.
References:
F. R. Alves, personal communication, 1985;.
BJORNBERG, A.J.S. and ELLERT, R. 1955. Observacoes geologicos e petrograficas sobre a Ilha dos Buzios. Anais da Academia de Ciencias, 27: 169-82
Map:
Fig. 1_213 Ilha dos Buzios (F. R. Alves, personal communication, 1985).
Location: