Classification of Sandstone: Analysis and Proposal

Nearly 50 schemes of sandstone classification have been proposed since Krynine's establishment of a modern classificatory method in 1948. Some attempts to solve the problems lying behind such a proliferation of classification schemes have been made by Klein, Shutov, Crook, and others with constructive criticisms. I analyzed integratively most of the proposed schemes and concluded: (1) the notion of three basic rock-types: (orthoquartzite, graywacke, arkose) should be abandoned because of their inadequate connection with diastrophic cycles and their ambiguous and confused definition, (2) the concept of fluidity factor or textural maturity cannot be applied strictly to indurated sandstones in orogenic belts, (3) sandstone composition depends upon the mean grain size, and (4) the ratio of quartz: feldspar: rock fragments is variable with mean grain size and amount of "clay-matrix." A threefold classification: (grain size, amount of clay matrix, composition of framework constituents) is recommended for sandstone classification; it represents a modification of Gilbert's classification, thus avoiding introducing new terms.