Change of the sedimentation microstructures of clay deposits during lithogenesis

Layer clay minerals are characterized by various habits of platy microblocks. Kaolinite consists of the largest (along the c axis) particles with up to isometric habit. Hydromica and chlorite are formed primarily by pseudoisometric microblocks, the thinnest of all observed ones. Montmorillonite exists as ultramicroblocks, which form microaggregates. Sedimentation microstructures of clay rocks as well as kaolinite domains and montmorillonite microaggregates successively break with depth. This determines the degree of orientation of the mineral particles in them at each stage of postsedimentation transformation of deposits and their products. Thus, in the section of the Late Precambrian deposits of the Yenisei Range and adjacent areas of the southern Siberian Platform, the best orientation of clay particles is characteristic of chlorite-hydromica strata, and the worst is observed in strata bearing, in addition, kaolinite or significant admixtures of silty material.