Formation of authigenic clays in Mesozoic sediments of Fergana Depression

The humid-acid and arid-alkaline conditions of sedimentation, Jurassic and Cretaceous respectively, have recognizable expressions in associations of clay minerals (fig. 2), which by comprehensive analyses, comparisons, and other studies and identifications, type-by-type and stage-by-stage, prove to be authigenic. Prevalence of kaolin or montmorillonite (with palygorskite) are expressions of the humid-acid and arid-alkaline environments of the authigenes. There seems no definite relationship of the kind for authigenic hydromicas.