Alkaline Rocks and Carbonatites of the World

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

Canama

stripes

Occurrence number: 
025-00-013
Country: 
Brazil
Region: 
Mato Grosso
Location: 
Longitude: -58.75, Latitude: -10.08
Carbonatite: 
No

Canama is an oval-shaped intrusion of syenites of 21x12 km. The principal rocks are nordmarkites, but alkali granites also occur which are composed essentially of orthoclase or perthite with riebeckite, hastingsite/barkevikite, aegirine-augite, a little biotite and quartz and accessory apatite, zircon, sphene, fluorite and rutile (?perovskite). Strong geochemical anomalies for Ti, Zr, Nb etc. have been detected (Issler, 1977).

Age: 
A whole rock Rb-Sr isochron (five syenites and a granite) gave 1175±15 Ma and K-Ar on biotite 1169±57 Ma (Issler, et al. 1974 quoting Basei, Radam unpublished internal Report).
References: 

ISSLER, R.S., ANDRADE, A.R.F. de, MONTALVAO, R.M.G. de, GUIMARAES, G., SILVA, G.G. da and LIMA, M.I.C. de, 1974. DNPM Projeto Radambrasil. Folha SA.22 Belem. Levantamento de Recursos Naturais, Geologia, 5.
ISSLER, R.S. 1977. Esboco geologico-tectonico do Craton do Guapore. Revista Brasileira de Geociencias, 7: 177-211

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith