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Geological Society, London, Memoirs; 1958; v. 1; p. 5-71;
DOI: 10.1144/GSL.MEM.1958.001.01.01
© 1958 Geological Society of London

Ring Complexes in the Younger Granite Province of Northern Nigeria

This memoir presents a summary of recent studies on the Nigerian Younger Granite complexes. Sufficient information is now available to indicate that the province includes some of the finest examples of granitic ring-complexes in the world.

The cycle of igneous activity was initiated by a volcanic phase during which large volumes of rhyolitic lavas were extruded. These lavas were succeeded by series of granitic intrusions whose emplacement and form have been mainly controlled by ring-fracturing and major block subsidence. As a result of the extensive down-faulting accompanying the granite emplacement, some of the rhyolites have been preserved at the present erosion level. Basic and intermediate rocks occur in some of the complexes.

The memoir is divided into two main sections. The first includes a general discussion of the essential structural, petrographic and geochemical characteristics of the province. The second section is devoted to the description of individual complexes which have been selected to illustrate the varieties of structure and rock type which are encountered.