stripes
Occurrence number:
025-00-092
Country:
Brazil
Region:
Sao Paulo
Location:
Longitude: -45, Latitude: -23.75
Carbonatite:
No
This island of less than 2 km2 consists of nepheline syenite, pulaskite and syenite, with or without quartz and with gradational boundaries between them. Modal nepheline increases from east to west and its concentration indicates a submerged nepheline syenite centre 1 km west of the island. Dykes are numerous and varied, including trachytes, with and without nepheline, phonolites, some with sodalite, bostonites and teschenites.
References:
MOTOKI, A. and GOMES, C.B. 1984. Caracterizacao geologica e petrografica do macico alcalino da Ilha de Vitoria, SP. Anais Congresso Brasileiro de Geologia, 33: 4392-9
Map:
Fig. 1_212 Ilha da Vitoria (after Motoki and Gomes, 1984, Fig. 1).
Location: