Suggested naming and classification of the word facies

Lithofacies paleogeography analysis and mapping are key fundamental works in energy resources investigation and exploration. However, in regard to the analysis of sedimentary facies, agreement of the definition, usage and classification of facies have not been achieved, both in foreign and domestic. This work presents a systematic review of the evolution of the term "facie" from its birth. Combined with the opinions and usage habits of most researchers, this paper recommends the definition of "facies" as "material expression of sedimentary environment, including physical, chemical and biological properties". For the name of facies, if we focus on the lithology, we can utilize the name of a specific lithology before the facies, such as limestone facies; if we focus on the sedimentary environment, we can utilize the name of a specific environment before the facies, such as fluvial facies; if we focus on the genesis, we can utilize the name of a specific genesis before the facies, such as turbidity facies; if we focus on the biological features, we can utilize the name of a specific biology before the facies, such as graptolite facies; if we focus on the tectonic background, we can utilize the name of the specific product of a tectonic setting before the facies, such as molasse facies. The name and classification of environment-oriented facies should follow the principle of "environment + facies ". Facies-subfacies-suborder facies are recommended in this study for the description and classification of facies according to different levels of investigation. In detail, facies is the material expression of sedimentary environment, subfacies is the material expression of sub-environment of facies, suborder facies is the material expression of sub-environment of subfacies. While microfacies should be the biological and sedimentary features that observed in rock thin-section, peel and polished surface.