Sucunduri Dome
Sucunduri is a 700 km2 dome in the Precambrian Teles Pires and Beneficente Groups, which is pierced by a number of plugs, necks and dykes of alkali syenite, lusitanite and nepheline syenite, with some phonolite and trachyte flows.
Complete list of alkaline rocks and carbonatites
Sucunduri is a 700 km2 dome in the Precambrian Teles Pires and Beneficente Groups, which is pierced by a number of plugs, necks and dykes of alkali syenite, lusitanite and nepheline syenite, with some phonolite and trachyte flows.
Canama is an oval-shaped intrusion of syenites of 21x12 km.
This irregularly shaped intrusion, approximately 5x2.5 km, consists principally of syenites but with granites and trachytes/phonolites also occurring.
The Rondonianas granites comprise over 30, usually circular, anorogenic intrusions emplaced in the Xingu complex of granulites, migmatites and gneisses. Most of the granites are biotite-bearing rapakivi types, but a number are peralkaline (see also Teotonio, 025-00-016).
One of the Rondonianas granites (see 025-00-015). Teotonio is a circular intrusion 4 km in diameter cut by the Madeira River, which covers more than half of it.
An intrusion composed of rock described as litchfieldite occurs at Morro da Estrela, 45 km northwest of the town of Porto Nacional.
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).
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).
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).
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).