Alkaline Rocks and Carbonatites of the World

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

Circular Structure

stripes

Occurrence number: 
025-00-021
Country: 
Brazil
Region: 
Maranhao
Location: 
Longitude: -46.27, Latitude: -7.67
Carbonatite: 
No

A major concentration of circular structures occurs in northeastern Brazil in the states of Maranhao and Piaui with one in Goias. Most show evidence of doming and they are thought probably to be underlain by alkaline intrusions. Those listed are taken from Rodrigues and Lima (1984).

References: 

PESSOA, R.R. 1975. Perspectivas de ocorrencias de complexos alcalinos no nordeste Brasileiro e sua importancia economica. Atas do Simposio de Geografia Geologia, Fortaleza, 7: 319-26.
RODRIGUES, C. de S. and LIMA, P.R.A. dos S. 1984. Carbonatitic complexes in Brazil. Companhia Brasileira de Metalurgia e Mineracao: 1-17

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