A lava flow with a maximum thickness of 20 m outcrops over a semicircular area less than 1 km in diameter, 4.5 km southeast of Volta Redonda. It is associated with sediments of the Resenda Formation.
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Rio de Janeiro
This is an area of alkaline rocks which includes much of the island of Cabo Frio (6.3 km2) together with the smaller intrusions of Morro do Forno and Atalaia on the adjacent mainland; there is an abundant dyke suite.
This is a small intrusion of trachyte.
This is a multiple intrusion covering approximately 30 km2 which is related to the nearby Tangua and Rio Bonito (Fig. 2_206) intrusions.
Rio Bonito is a zoned stock of some 28 km2 emplaced in Precambrian gneisses and granulites near to the Tangua and Saorinho intrusions (Fig. 2_206).
This approximately circular intrusion 6-7 km in diameter is cut by plugs of intrusive breccia, and emplaced in Precambrian biotite gneisses and granulites, close to Saorinho and Rio Bonito (Fig. 2_206).
A small intrusion of volcanic breccia cuts Tertiary sediments of the Barreiras Formation. It contains small alkaline rock fragments 1-10 mm in diameter in a phonolitic matrix of orthoclase, nepheline, cancrinite, pyroxene and secondary calcite.
A small plug of porphyritic phonolite cuts Tertiary sediments of the Barreiras Formation. Phenocrysts of feldspar, aegirine, nepheline and mica occur and analcime is present in amygdales.
Itauna covers 6 km2 and comprises a number of incomplete but concentric rings and a central plug. It is emplaced into Precambrian gneisses. Pseudoleucite syenites and microsyenites are intruded by a central core of pseudoleucite phonolite.
This is a small phonolite plug.