Observations petrographiques sur les meulieres pliocenes

Abstract

Abstract Millstone capping the Pliocene sequence of the Beni-Abbes region, Algeria, exhibits a genetic relationship with underlying sandstone. Numerous grains of detrital quartz clearly show the effects of solution which could have been the source of the secondary silica (chalcedony and quartz). Induration was a near-surface process. Iron oxides, gypsum, and perhaps calcium carbonate appear to have played a role in the processes of substitution and induration.