ON THE CLASSIFICATION OF SANDSTONES

Over the last three-quarters of a century various grain-based classification systems have been developed in order to categorize sandstones on the basis of the relative abundances of their three most common components: quartz, feldspar, and rock fragments. A review of the historical development of sandstone classification is undertaken to elucidate evolution in geological understanding represented by various methodologies of classification. The compositional fields defined in traditional sandstone classifications are found to be largely incompatible with subpopulations of sandstones grouped according to interpreted sedimentary tectonic provenance. The origin of this incompatibility between descriptive classifications and genetic classifications arose from the fact that neither approach established classification field boundaries on the basis of processes known to control the origin and evolution of sandstone composition. The development of the study of a range of factors that influence sandstone petrogenesis and grain composition are reviewed along with the introduction of several critical statistical techniques applicable to multicomponent grain abundance analysis. From the understandings gained by the evaluation of these advances in classification practice a set of potential topics for future consideration are introduced.