The photogeological recognition of ancient orogenic belts in Africa

Abstract

Photogeological interpretation, assisted by some ground control, has been used to delineate areas of the crystalline basement in which structures formed during a particular tectonism are predominant. Such areas are referred to as 'tectonic domains'. They are recognized principally by distinctive tectonic style, by characteristic trend and axial direction, by metamorphic grade and by the sequence ot imposition of tectonisms. These criteria may be supported by geophysical data. It is unusual for all the criteria to be satisfied photogeologically, but with some ground information it is possible to draw maps which show the distribution of tectonic domains.