stripes
Occurrence number:
025-00-006
Country:
Brazil
Region:
Para
Location:
Longitude: -55.67, Latitude: 1.08
Carbonatite:
No
This is a nearly circular intrusion some 2 km in diameter which is classified as part of the Uatuma Group igneous cycle (1900-1400 Ma). The principal rock type is a quartz syenite containing perthite, quartz, plagioclase (albite-andesine), hastingsitic amphibole, biotite, sphene, zircon, opaques, apatite and fluorite. Chemical analyses in Oliveira et al. (1975) indicate K2O>Na2O. It is only marginally alkaline.
Age:
1806±69 Ma by Rb-Sr on syenite (Oliveira et al. 1975; Montalvao, 1976).
References:
OLIVEIRA, A. da S., FERNANDES, C.A.C., ISSLER, R.S., ABREU, A.S., MONTALVAO, R.M.G. de and TEIXEIRA, W. 1975. Folha NA.21 Tumucumaque e parte da Folha NB.21. DNPM Projeto.
MONTALVAO, R.M.G. de, 1976. Esboco geologico-tectonico do Craton Guianes. Revista Brasileira de Geociencias, 6: 230-45
Location: